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Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2013	Jul. 31, 2013
Document And Entity Information [Abstract]
Entity Registrant Name	NBT BANCORP INC
Entity Central Index Key	0000790359
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		43,587,942
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q2
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2013

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2013	Dec. 31, 2012
Assets
Cash and due from banks	$ 142,570	$ 157,094
Short-term interest bearing accounts	1,117	6,574
Securities available for sale, at fair value	1,390,403	1,147,999
Securities held to maturity (fair value $121,069 and $61,535, respectively)	122,302	60,563
Trading securities	5,092	3,918
Federal Reserve and Federal Home Loan Bank stock	43,491	29,920
Loans and leases	5,290,710	4,277,616
Less allowance for loan and lease losses	71,184	69,334
Net loans and leases	5,219,526	4,208,282
Premises and equipment, net	87,811	77,875
Goodwill	264,376	152,373
Intangible assets, net	28,204	16,962
Bank owned life insurance	112,907	80,702
Other assets	116,719	99,997
Total assets	7,534,518	6,042,259
Liabilities
Demand (noninterest bearing)	1,516,385	1,242,712
Savings, NOW, and money market	3,256,753	2,558,376
Time	1,105,038	983,261
Total deposits	5,878,176	4,784,349
Short-term borrowings	385,611	162,941
Long-term debt	309,111	367,492
Trust preferred debentures	101,196	75,422
Other liabilities	68,849	69,782
Total liabilities	6,742,943	5,459,986
Stockholders' equity
Preferred stock, $0.01 par value. Authorized 2,500,000 shares at June 30, 2013 and December 31, 2012	0	0
Common stock, $0.01 par value. Authorized 100,000,000 shares at June 30, 2013 and December 31, 2012; issued 49,651,494 at June 30, 2013 and 39,305,131 at December 31, 2012	497	393
Additional paid-in-capital	572,359	346,692
Retained earnings	366,555	357,558
Accumulated other comprehensive loss	(21,586)	(5,880)
Common stock in treasury, at cost, 6,116,825 and 5,529,781 shares at June 30, 2013 and December 31, 2012, respectively	(126,250)	(116,490)
Total stockholders' equity	791,575	582,273
Total liabilities and stockholders' equity	$ 7,534,518	$ 6,042,259

Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2013	Dec. 31, 2012
Assets
Securities held to maturity fair value	$ 121,069	$ 61,535
Stockholders' equity
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	2,500,000	2,500,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	49,651,494	39,305,131
Common stock in treasury, at cost (in shares)	6,116,825	5,529,781

Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Interest, fee, and dividend income
Interest and fees on loans and leases	$ 62,031	$ 50,509	$ 115,726	$ 100,717
Securities available for sale	6,537	7,108	12,283	14,474
Securities held to maturity	548	617	1,073	1,257
Other	488	413	891	805
Total interest, fee, and dividend income	69,604	58,647	129,973	117,253
Interest expense
Deposits	4,296	4,834	8,446	9,977
Short-term borrowings	67	48	109	89
Long-term debt	3,026	3,580	6,635	7,161
Trust preferred debentures	560	434	988	883
Total interest expense	7,949	8,896	16,178	18,110
Net interest income	61,655	49,751	113,795	99,143
Provision for loan and lease losses	6,402	4,103	12,060	8,574
Net interest income after provision for loan and lease losses	55,253	45,648	101,735	90,569
Noninterest income
Insurance and other financial services revenue	5,755	5,279	12,648	11,433
Service charges on deposit accounts	4,933	4,571	9,256	8,912
ATM and debit card fees	4,044	3,063	7,286	6,025
Retirement plan administration fees	2,957	2,411	5,639	4,744
Trust	4,699	2,312	7,612	4,441
Bank owned life insurance	886	618	1,735	1,589
Net securities (losses) gains	(61)	97	1,084	552
Other	2,324	2,331	5,506	6,042
Total noninterest income	25,537	20,682	50,766	43,738
Noninterest expense
Salaries and employee benefits	29,160	24,992	56,207	51,717
Occupancy	5,219	4,222	10,196	8,713
Data processing and communications	3,854	3,431	7,309	6,689
Professional fees and outside services	3,237	2,388	6,138	5,113
Equipment	2,910	2,409	5,492	4,789
Office supplies and postage	1,656	1,574	3,246	3,245
FDIC expenses	1,273	942	2,403	1,873
Advertising	1,000	805	1,723	1,607
Amortization of intangible assets	1,351	841	2,202	1,660
Loan collection and other real estate owned	421	799	1,139	1,437
Merger expenses	1,269	826	11,950	1,337
Other	5,100	4,161	9,150	7,684
Total noninterest expense	56,450	47,390	117,155	95,864
Income before income tax expense	24,340	18,940	35,346	38,443
Income tax expense	7,424	5,683	10,781	11,536
Net income	$ 16,916	$ 13,257	$ 24,565	$ 26,907
Earnings per share
Basic (in dollars per share)	$ 0.39	$ 0.40	$ 0.61	$ 0.81
Diluted (in dollars per share)	$ 0.38	$ 0.40	$ 0.61	$ 0.80

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 16,916	$ 13,257	$ 24,565	$ 26,907
Other comprehensive income, net of tax
Unrealized net holding (losses) gains arising during the period (pre-tax amounts of ($24,712), ($309), (26,464) and $335)	(14,923)	(185)	(15,978)	201
Reclassification adjustment for net gains related to securities available for sale included in net income (pre-tax amounts of ($61), $97, $1,084 and $552)	37	(58)	(650)	(331)
Pension and other benefits:
Amortization of prior service cost and actuarial gains (pre-tax amounts of $710, $856, $1,536 and $1,713)	426	511	922	1,027
Total other comprehensive income	(14,460)	268	(15,706)	897
Comprehensive income	$ 2,456	$ 13,525	$ 8,859	$ 27,804

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Other comprehensive (loss) income, before tax
Unrealized net holding (losses) gains arising during the period, pre-tax amounts	$ (24,712)	$ (309)	$ (26,464)	$ (335)
Reclassification adjustment for net gains related to securities available for sale included in net income, pre-tax amounts	(61)	97	1,084	552
Amortization of prior service cost and actuarial gains, pre-tax amounts	$ 710	$ 856	$ 1,536	$ 1,713

Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in-Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Common Stock in Treasury [Member]	Total
Beginning Balance at Dec. 31, 2011	$ 380	$ 317,329	$ 329,981	$ (6,104)	$ (103,476)	$ 538,110
Net income	0	0	26,907	0	0	26,907
Cash dividends	0	0	(13,232)	0	0	(13,232)
Purchase of treasury shares	0	0	0	0	(15,490)	(15,490)
Net issuance of shares for acquisition	13	25,811	0	0	0	25,824
Net issuance of shares to employee benefit plans and other stock plans, including tax benefit	0	(753)	(196)	0	1,641	692
Stock-based compensation	0	2,797	0	0	0	2,797
Other comprehensive income	0	0	0	897	0	897
Ending Balance at Jun. 30, 2012	393	345,184	343,460	(5,207)	(117,325)	566,505
Beginning Balance at Dec. 31, 2012	393	346,692	357,558	(5,880)	(116,490)	582,273
Net income	0	0	24,565	0	0	24,565
Cash dividends	0	0	(15,568)	0	0	(15,568)
Purchase of treasury shares	0	0	0	0	(5,460)	(5,460)
Net issuance of shares for acquisition	104	225,447	0	0	(5,779)	219,772
Net issuance of shares to employee benefit plans and other stock plans, including tax benefit	0	(2,506)	0	0	1,479	(1,027)
Stock-based compensation	0	2,726	0	0	0	2,726
Other comprehensive income	0	0	0	(15,706)	0	(15,706)
Ending Balance at Jun. 30, 2013	$ 497	$ 572,359	$ 366,555	$ (21,586)	$ (126,250)	$ 791,575

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

Consolidated Statements of Stockholders' Equity (Unaudited) (Parenthetical) - $ / shares	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Consolidated Statements of Stockholders' Equity (Unaudited) [Abstract]
Cash dividends - per share (in dollars per share)	$ 0.40	$ 0.40
Purchase of treasury shares (in shares)	267,425	769,568
Net issuance of shares for acquisition (in shares)	10,346,363	1,269,592
Treasury stock reissued in acquisition of Alliance (in shares)	408,957
Net issuance of shares to employee benefit plans and other stock plans, including tax benefit (in shares)	89,338	79,052

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Operating activities
Net income	$ 24,565	$ 26,907
Adjustments to reconcile net income to net cash provided by operating activities
Provision for loan and lease losses	12,060	8,574
Depreciation and amortization of premises and equipment	3,828	3,020
Net accretion on securities	2,811	1,197
Amortization of intangible assets	2,202	1,660
Stock based compensation	2,726	2,797
Bank owned life insurance income	(1,735)	(1,589)
Purchases of trading securities	(949)	(657)
Unrealized (gains) losses in trading securities	(225)	78
Deferred income tax benefit	(519)	(1,794)
Proceeds from sale of loans held for sale	39,060	28,774
Originations and purchases of loans held for sale	(40,233)	(34,182)
Net gains on sales of loans held for sale	(817)	(894)
Net security gains	(1,084)	(552)
Net gains on sales of other real estate owned	(571)	(417)
Net decrease in other assets	9,144	11,099
Net decrease in other liabilities	(8,333)	(10,897)
Net cash provided by operating activities	41,930	33,124
Investing activities
Net cash provided by acquisitions	80,909	53,121
Securities available for sale:
Proceeds from maturities, calls, and principal paydowns	234,543	205,390
Proceeds from sales	26,236	1,791
Purchases	(219,000)	(185,112)
Securities held to maturity:
Proceeds from maturities, calls, and principal paydowns	16,822	16,655
Purchases	(71,988)	(9,858)
Net increase in loans	(119,872)	(142,433)
Net increase in Federal Reserve and FHLB stock	(5,584)	(672)
Purchases of premises and equipment	(2,272)	(2,769)
Proceeds from sales of other real estate owned	2,122	1,661
Net cash used in investing activities	(58,084)	(62,226)
Financing activities
Net (decrease) increase in deposits	(19,593)	39,653
Net increase in short-term borrowings	201,066	30,611
Repayments of long-term debt	(163,307)	(3,347)
Proceeds from the issuance of shares to employee benefit plans and other stock plans	(965)	690
Purchase of treasury stock	(5,460)	(15,490)
Cash dividends and payment for fractional shares	(15,568)	(13,232)
Net cash used in financing activities	(3,827)	38,885
Net (decrease) increase in cash and cash equivalents	(19,981)	9,783
Cash and cash equivalents at beginning of period	163,668	129,381
Cash and cash equivalents at end of period	143,687	139,164
Cash paid during the period for:
Interest	16,853	18,245
Income taxes paid	4,525	14,122
Noncash investing activities:
Loans transferred to OREO	3,031	889
Acquisitions:
Fair value of assets acquired	1,503,810	258,256
Fair value of liabilities assumed	1,284,038	285,403
Fair value of debt issued in purchase combination	$ 0	$ 150

Description of Business

6 Months Ended

Jun. 30, 2013

Description of Business [Abstract]

Description of Business

Note 1.

Description of Business

NBT Bancorp Inc. (the “Registrant”) is a registered financial holding company incorporated in the State of Delaware in 1986, with its principal headquarters located in Norwich, New York. The Registrant is the parent holding company of NBT Bank, N.A. (the “Bank”), NBT Financial Services, Inc. (“NBT Financial”), NBT Holdings, Inc. (“NBT Holdings”), CNBF Capital Trust I, NBT Statutory Trust I, NBT Statutory Trust II, Alliance Financial Capital Trust I and Alliance Financial Capital Trust II (the “Trusts”). Through the Bank, the Company is focused on community banking operations. Through NBT Financial, the Company operates EPIC Advisors, Inc. (“EPIC”), a retirement plan administrator. Through NBT Holdings, the Company operates Mang Insurance Agency, LLC (“Mang”), a full-service insurance agency. The Trusts were organized to raise additional regulatory capital and to provide funding for certain acquisitions. The Registrant’s primary business consists of providing commercial banking and financial services to customers in its market area. The principal assets of the Registrant are all of the outstanding shares of common stock of its direct subsidiaries, and its principal sources of revenue are the management fees and dividends it receives from the Bank, NBT Financial, and NBT Holdings.

The Bank is a full service commercial bank formed in 1856, which provides a broad range of financial products to individuals, corporations and municipalities throughout the central and upstate New York, northeastern Pennsylvania, northwestern Vermont, western Massachusetts, and southern New Hampshire market areas.

Basis of Presentation

6 Months Ended

Jun. 30, 2013

Basis of Presentation [Abstract]

Basis of Presentation

Note 2.

Basis of Presentation

The accompanying unaudited interim consolidated financial statements include the accounts of the Registrant and its wholly owned subsidiaries, the Bank, NBT Financial and NBT Holdings. Collectively, the Registrant and its subsidiaries are referred to herein as “the Company.” The interim data includes all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of the results for the interim periods in accordance with generally accepted accounting principles (“GAAP”). These consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in our 2012 Annual Report on Form 10-K. The results of operations for the interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period. All intercompany transactions have been eliminated in consolidation. Amounts in the prior period financial statements are reclassified whenever necessary to conform to current period presentation. The Company has evaluated subsequent events for potential recognition and/or disclosure and there were none identified.

- Definition

The entire disclosure for organization, consolidation and basis of presentation of financial statements disclosure.

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+ Details

Acquisition

6 Months Ended

Jun. 30, 2013

Acquisition [Abstract]

Acquisition

Note 3.

Acquisitions

Alliance Financial Corporation (“Alliance”)

On March 8, 2013, the Company acquired Alliance, the parent company of Alliance Bank, N.A., for total consideration of $226 million. As part of the acquisition, Alliance was merged with and into the Company and Alliance Bank, with 26 branch locations in the central New York counties of Onondaga, Cortland, Madison, Oneida and Oswego, was merged with and into the Bank. The merger with Alliance enabled the Company to expand its footprint into demographically attractive and contiguous markets located in the aforementioned New York counties. Alliance operations were integrated into the Company and were included in the Consolidated Statements of Income from the date of acquisition.

Under the terms of the merger agreement, each outstanding share of Alliance common stock was converted into the right to receive 2.1779 shares of the Company’s common stock. As a result, Alliance shareholders received 10.3 million shares of Company common stock valued at $226 million.

In connection with the merger, the consideration paid and the fair value of the assets acquired and the liabilities assumed on the date of acquisition are as summarized in the following table, in thousands:

Consideration paid:
NBT Bancorp common stock issued to Alliance common shareholders	$	225,551
Cash in lieu of fractional shares paid to Alliance common shareholders		11
Less treasury shares		5,779

Net consideration paid	$	219,783

Recognized Amounts of Identifiable Assets Acquired and (Liabilities Assumed) At Fair Value:
Cash and short term investments	$	81,060
Securities		320,618
Loans		904,473
Intangible assets		13,161
Other assets		71,823
Deposits		(1,113,420	)
Borrowings		(126,530	)
Trust preferred debentures		(25,774	)
Other liabilities		(18,466	)
Total identifiable net assets	$	106,945

Goodwill	$	112,838

The above recognized amounts of loans, other assets and other liabilities, at fair value, are preliminary estimates and are subject to adjustment but actual amounts are not expected to differ materially from those shown.

The estimated fair value of loans acquired from Alliance was determined by utilizing a methodology wherein similar loans were aggregated into pools. Cash flows for each pool were determined by estimating future credit losses and the rate of prepayments. Projected monthly cash flows were then discounted to present value based on a current market rate for similar loans. There was no carryover of Alliance’s allowance for credit losses associated with the loans acquired as loans were initially recorded at fair value.

Information about the acquired loan portfolio as of March 8, 2013 is as follows (in thousands):

Contractually required principal and interest at acquisition	$	908,614
Contractual cash flows not expected to be collected		(15,466	)
Expected cash flows at acquisition		893,148
Interest component of expected cash flows (accretable premium)		11,325
Fair value of acquired loans	$	904,473

The following table presents changes in the accretable discount (in thousands):

Balance at January 1, 2013	$	-
Alliance acquisition		11,325
Accretion recognized to date		(994	)
Balance at June 30, 2013	$	10,331

The core deposit and trust intangible assets recognized as part of the Alliance merger are being amortized over their estimated useful lives of approximately 10 and 15 years, respectively, utilizing an accelerated method. The goodwill, which is not amortized for book purposes, is not deductible for tax purposes.

The fair value of savings and transaction deposit accounts acquired from Alliance was assumed to approximate the carrying value as these accounts have no stated maturity and are payable on demand. Certificates of deposit were valued by projecting the expected cash flows based on the contractual terms of the certificates of deposit. These cash flows were discounted based on a current market rate for a certificate of deposit with a corresponding maturity.

The fair value of borrowings, which was comprised of FHLB advances, was determined by obtaining settlement quotes from the FHLB.

Direct costs related to the Alliance acquisition were expensed as incurred and amounted to $12.0 million for the six months ended June 30, 2013.

The following table presents unaudited pro forma information as if the acquisition had occurred on January 1, 2012 under the “Pro forma” columns. This pro forma information gives effect to certain adjustments, including purchase accounting fair value adjustments, amortization of core deposit and other intangibles and related income tax effects. Merger and acquisition integration costs related to the Alliance acquisition are excluded from the periods in which they were incurred. The pro forma information does not necessarily reflect the results of operations that would have occurred had the Company merged with Alliance at the beginning of 2012. Cost savings are also not reflected in the unaudited pro forma amounts for the six months ended June 30, 2012 and 2013.

	Pro forma
	Six months ended June 30,
	2013		2012

Net interest income	$	120,593	$	119,471
Noninterest income		55,445		52,738
Net income		33,911		32,104

Supplemental financial information regarding the former Alliance operations included in our Consolidated Statement of Income from the date of acquisition through June 30, 2013 has not been provided as it would be impracticable to do so. The operations of Alliance have been integrated into the Bank’s operations and therefore financial information specific to revenues and expense associated with the former Alliance operations is not accessible.

Other Goodwill Adjustments

During the six months ended June 30, 2013, the Company recorded a deferred tax adjustment related to the 2012 acquistion of Hampshire First Bank resulting in a decrease in goodwill of approximately $1.0 million. In addition, the Company recorded a goodwill adjustment of approximately $0.1 million related to the 2012 acquisition of a financial services company.

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=25497992&loc=d3e1497-128463

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Commitments and Contingencies

6 Months Ended

Jun. 30, 2013

Commitments and Contingencies [Abstract]

Commitments and Contingencies

Note 4.

Commitments and Contingencies

The Company is a party to financial instruments in the normal course of business to meet the financing needs of its customers and to reduce its own exposure to fluctuating interest rates. These financial instruments include commitments to extend credit, unused lines of credit, and standby letters of credit. Exposure to credit loss in the event of nonperformance by the other party to the financial instrument for commitments to make loans and standby letters of credit is represented by the contractual amount of those instruments. The Company uses the same credit origination guidelines, portfolio maintenance and management procedures as other credit and off-balance sheet products. Commitments to extend credit and unused lines of credit totaled $1.1 billion at June 30, 2013 and $841.7 million at December 31, 2012. Since commitments to extend credit and unused lines of credit may expire without being fully drawn upon, this amount does not necessarily represent future cash commitments. Collateral obtained upon exercise of the commitment is determined using management’s credit evaluation of the borrower and may include accounts receivable, inventory, property, land and other items.

The Company guarantees the obligations or performance of customers by issuing standby letters of credit to third parties. These standby letters of credit are frequently issued in support of third party debt, such as corporate debt issuances, industrial revenue bonds and municipal securities. The credit risk involved in issuing standby letters of credit is essentially the same as the credit risk involved in extending loan facilities to customers, and they are subject to the same credit origination guidelines, portfolio maintenance and management procedures as other credit and off-balance sheet products. Typically, these instruments have terms of five years or less and expire unused; therefore, the total amounts do not necessarily represent future cash commitments. Standby letters of credit totaled $41.5 million at June 30, 2013 and $37.5 million at December 31, 2012. As of June 30, 2013, the fair value of standby letters of credit was not significant to the Company’s consolidated financial statements.

The Company has also entered into commercial letter of credit agreements on behalf of its customers. Under these agreements, the Company, on the request of its customer, opens the letter of credit and makes a commitment to honor draws made under the agreement, whereby the beneficiary is normally the provider of goods and/or services and the Company essentially replaces the customer as the payee. The credit risk involved in issuing commercial letters of credit is essentially the same as the credit risk involved in extending loan facilities to customers, and they are subject to the same credit origination guidelines, portfolio maintenance and management procedures as other credit and off-balance sheet products. Typically, these agreements vary in terms and the total amounts do not necessarily represent future cash commitments. Commercial letters of credit totaled $36.9 million at June 30, 2013 and $16.6 million at December 31, 2012. As of June 30, 2013, the fair value of commercial letters of credit was not significant to the Company’s consolidated financial statements.

Allowance for Loan Losses and Credit Quality of Loans

6 Months Ended

Jun. 30, 2013

Allowance for Loan Losses and Credit Quality of Loans [Abstract]

Allowance for Loan Losses and Credit Quality of Loans

Note 5. Allowance for Loan Losses and Credit Quality of Loans

Allowance for Loan Losses

The allowance for loan losses is maintained at a level estimated by management to provide adequately for risk of probable losses inherent in the current loan portfolio. The adequacy of the allowance for loan losses is continuously monitored. It is assessed for adequacy using a methodology designed to ensure the level of the allowance reasonably reflects the loan portfolio’s risk profile. It is evaluated to ensure that it is sufficient to absorb all reasonably estimable credit losses inherent in the current loan portfolio.

To develop and document a systematic methodology for determining the allowance for loan losses, the Company has divided the loan portfolio into three segments, each with different risk characteristics and methodologies for assessing risk. Those segments are further segregated between our loans accounted for under the amortized cost method (referred to as “originated” loans) and loans acquired in a business combination (referred to as “acquired” loans). Prior to 2013, separate disclosures for acquired loans were not significant and were included with originated loans in the Company’s asset quality disclosures. Each portfolio segment is broken down into class segments where appropriate. Class segments contain unique measurement attributes, risk characteristics and methods for monitoring and assessing risk that are necessary to develop the allowance for loan losses. Unique characteristics such as borrower type, loan type, collateral type, and risk characteristics define each class segment. The following table illustrates the portfolio and class segments for the Company’s loan portfolio:

Portfolio	Class
Commercial Loans	Commercial
	Commercial Real Estate
	Agricultural
	Agricultural Real Estate
	Business Banking

Consumer Loans	Indirect
	Home Equity
	Direct

Residential Real Estate Mortgages

Commercial Loans

The Company offers a variety of commercial loan products including commercial (non-real estate), commercial real estate, agricultural, agricultural real estate, and business banking loans. The Company’s underwriting analysis for commercial loans typically includes credit verification, independent appraisals, a review of the borrower’s financial condition, and a detailed analysis of the borrower’s underlying cash flows.

Commercial – The Company offers a variety of loan options to meet the specific needs of our commercial customers including term loans, time notes and lines of credit. Such loans are made available to businesses for working capital needs such as inventory and receivables, business expansion and equipment purchases. Generally, a collateral lien is placed on equipment or other assets owned by the borrower. These loans carry a higher risk than commercial real estate loans due to the nature of the underlying collateral, which can be business assets such as equipment and accounts receivable and is generally less liquid than real estate. To reduce the risk, management also attempts to secure real estate as collateral and obtain personal guarantees of the borrowers.

Commercial Real Estate – The Company offers commercial real estate loans to finance real estate purchases, refinancings, expansions and improvements to commercial properties. Commercial real estate loans are made to finance the purchases of real property which generally consists of real estate with completed structures. These commercial real estate loans are secured by first liens on the real estate, which may include apartments, commercial structures, housing businesses, healthcare facilities, and other non owner-occupied facilities. These loans are typically less risky than commercial loans, since they are secured by real estate and buildings, and are generally originated in amounts of no more than 80% of the appraised value of the property.

Agricultural – The Company offers a variety of agricultural loans to meet the needs of our agricultural customers including term loans, time notes, and lines of credit. These loans are made to purchase livestock, purchase and modernize equipment, and finance seasonal crop expenses. Generally, a collateral lien is placed on the livestock, equipment, produce inventories, and/or receivables owned by the borrower. These loans may carry a higher risk than commercial and agricultural real estate loans due to the industry price volatility, and in some cases, the perishable nature of the underlying collateral. To reduce these risks, management may attempt to secure these loans with additional real estate collateral, obtain personal guarantees of the borrowers, or obtain government loan guarantees to provide further support.

Agricultural Real Estate – The Company offers real estate loans to our agricultural customers to finance farm related real estate purchases, refinancings, expansions, and improvements to agricultural properties such as barns, production facilities, and land. The agricultural real estate loans are secured by first liens on the farm real estate. Because they are secured by land and buildings, these loans may be less risky than agricultural loans. These loans are typically originated in amounts of no more than 75% of the appraised value of the property. Government loan guarantees may be obtained to provide further support.

Business Banking - The Company offers a variety of loan options to meet the specific needs of our business banking customers including term loans, business banking mortgages and lines of credit. Such loans are generally less than $0.5 million and are made available to businesses for working capital such as inventory and receivables, business expansion, equipment purchases, and agricultural needs. Generally, a collateral lien is placed on equipment or other assets owned by the borrower such as inventory and/or receivables. These loans carry a higher risk than commercial loans due to the smaller size of the borrower and lower levels of capital. To reduce the risk, the Company obtains personal guarantees of the owners for a majority of the loans.

Consumer Loans

The Company offers a variety of consumer loan products including indirect, home equity, and direct loans.

Indirect – The Company maintains relationships with many dealers primarily in the communities that we serve. Through these relationships, the company finances the purchases of automobiles and recreational vehicles (such as campers, boats, etc.) indirectly through dealer relationships. Approximately 75% of the indirect relationships represent automobile financing. Most of these loans carry a fixed rate of interest with principal repayment terms typically ranging from three to six years, based upon the nature of the collateral and the size of the loan. The majority of indirect consumer loans are underwritten on a secured basis using the underlying collateral being financed.

Home Equity – The Company offers fixed home equity loans as well as home equity lines of credit to consumers to finance home improvements, debt consolidation, education and other uses. Consumers are able to borrow up to 85% of the equity in their homes. The Company originates home equity lines of credit and second mortgage loans (loans secured by a second junior lien position on one-to-four-family residential real estate). These loans carry a higher risk than first mortgage residential loans as they are in a second position with respect to collateral. Risk is reduced through underwriting criteria, which include credit verification, appraisals, a review of the borrower's financial condition, and personal cash flows. A security interest, with title insurance when necessary, is taken in the underlying real estate.

Direct – The Company offers a variety of consumer installment loans to finance vehicle purchases, mobile home purchases and personal expenditures. Most of these loans carry a fixed rate of interest with principal repayment terms typically ranging from one to ten years, based upon the nature of the collateral and the size of the loan. The majority of consumer loans are underwritten on a secured basis using the underlying collateral being financed or a customer's deposit account. In addition to installment loans, the Company also offers personal lines of credit and overdraft protection. A minimal amount of loans are unsecured, which carry a higher risk of loss.

Residential Real Estate Mortgages

Residential real estate loans consist primarily of loans secured by first or second deeds of trust on primary residences. We originate adjustable-rate and fixed-rate, one-to-four-family residential real estate loans for the construction, purchase or refinancing of a mortgage. These loans are collateralized by owner-occupied properties located in the Company’s market area. Loans on one-to-four-family residential real estate are generally originated in amounts of no more than 85% of the purchase price or appraised value (whichever is lower), or have private mortgage insurance. The Company’s underwriting analysis for residential mortgage loans typically includes credit verification, independent appraisals, and a review of the borrower’s financial condition. Mortgage title insurance and hazard insurance are normally required. Construction loans have a unique risk, because they are secured by an incomplete dwelling. This risk is reduced through periodic site inspections, including one at each loan draw period.

For purposes of evaluating the adequacy of the allowance, the Company considers a number of significant factors that affect the collectability of the portfolio. For individually analyzed loans, these include estimates of loss exposure, which reflect the facts and circumstances that affect the likelihood of repayment of such loans as of the evaluation date. For homogeneous pools of loans, estimates of the Company’s exposure to credit loss reflect a current assessment of a number of factors, which could affect collectability. These factors include: past loss experience; size, trend, composition, and nature of loans; changes in lending policies and procedures, including underwriting standards and collection, charge-offs and recoveries; trends experienced in nonperforming and delinquent loans; current economic conditions in the Company’s market; portfolio concentrations that may affect loss experienced across one or more components of the portfolio; the effect of external factors such as competition, legal and regulatory requirements; and the experience, ability, and depth of lending management and staff. In addition, various regulatory agencies, as an integral component of their examination process, periodically review the Company’s allowance for loan losses. Such agencies may require the Company to make loan grade changes as well as recognize additions to the allowance based on their examinations.

After a thorough consideration of the factors discussed above, any required additions or reductions to the allowance for loan losses are made periodically by charges or credits to the provision for loan losses. These charges or credits are necessary to maintain the allowance at a level which management believes is reasonably reflective of overall inherent risk of probable loss in the portfolio. While management uses available information to recognize losses on loans, additions and reductions of the allowance may fluctuate from one reporting period to another. These fluctuations are reflective of changes in risk associated with portfolio content and/or changes in management’s assessment of any or all of the determining factors discussed above.

The following tables illustrate the changes in the allowance for loan losses by our portfolio segments for the three and six months ended June 30, 2013 and 2012:

							Residential
Three months ended June 30	Commercial			Consumer			Real Estate
	Loans			Loans			Mortgages			Unallocated			Total
Balance as of March 31, 2013	$	35,358		$	26,285		$	6,708		$	383		$	68,734
Charge-offs		(1,198	)		(3,653	)		(302	)		-			(5,153	)
Recoveries		416			696			89			-			1,201
Provision		3,128			3,128			311			(165	)		6,402
Ending Balance as of June 30, 2013	$	37,704		$	26,456		$	6,806		$	218		$	71,184

Balance as of March 31, 2012	$	37,787		$	26,790		$	6,520		$	237		$	71,334
Charge-offs		(1,653	)		(3,735	)		(292	)		-			(5,680	)
Recoveries		303			667			7			-			977
Provision		1,058			3,513			(292	)		(176	)		4,103
Ending Balance as of June 30, 2012	$	37,495		$	27,235		$	5,943		$	61		$	70,734

							Residential
Six months ended June 30	Commercial			Consumer			Real Estate
	Loans			Loans			Mortgages			Unallocated			Total
Balance as of December 31, 2012	$	35,624		$	27,162		$	6,252		$	296		$	69,334
Charge-offs		(4,520	)		(7,376	)		(973	)		-			(12,869	)
Recoveries		883			1,673			103			-			2,659
Provision		5,717			4,997			1,424			(78	)		12,060
Ending Balance as of June 30, 2013	$	37,704		$	26,456		$	6,806		$	218		$	71,184

Balance as of December 31, 2011	$	38,831		$	26,049		$	6,249		$	205		$	71,334
Charge-offs		(2,783	)		(7,787	)		(650	)		-			(11,220	)
Recoveries		688			1,342			16			-			2,046
Provision		759			7,631			328			(144	)		8,574
Ending Balance as of June 30, 2012	$	37,495		$	27,235		$	5,943		$	61		$	70,734

For acquired loans, to the extent that we experience deterioration in borrower credit quality resulting in a decrease in our expected cash flows subsequent to acquisition of the loans, an allowance for loan losses would be established based on our estimate of future credit losses over the remaining life of the loans. As of June 30, 2013 and 2012, there was no allowance for loan losses for the acquired loan portfolio. Net charge-offs related to acquired loans totaled $0.2 million and $0.4 million during the three and six months ended June 30, 2013, respectively, and are included in the table above.

The following tables illustrate the allowance for loan losses and the recorded investment by portfolio segments as of June 30, 2013 and December 31, 2012:

Allowance for Loan Losses and Recorded Investment in Loans
(in thousands)

					Residential
	Commercial		Consumer		Real Estate
	Loans		Loans		Mortgages		Unallocated		Total
As of June 30, 2013
Allowance for loan losses	$	37,704	$	26,456	$	6,806	$	218	$	71,184

Allowance for loans individually evaluated for impairment	$	2,032	$	-	$	-			$	2,032

Allowance for loans collectively evaluated for impairment	$	35,672	$	26,456	$	6,806	$	218	$	69,152

Ending balance of loans	$	2,368,897	$	1,920,171	$	1,001,642			$	5,290,710

Ending balance of loans individually evaluated for impairment	$	12,887	$	-	$	-			$	12,887
Ending balance of acquired loans	$	460,995	$	269,151	$	338,750			$	1,068,896
Ending balance of loans collectively evaluated for impairment	$	1,895,015	$	1,651,020	$	662,892			$	4,208,927

As of December 31, 2012
Allowance for loan losses	$	35,624	$	27,162	$	6,252	$	296	$	69,334

Allowance for loans individually evaluated for impairment	$	2,848	$	-	$	-			$	2,848

Allowance for loans collectively evaluated for impairment	$	32,776	$	27,162	$	6,252	$	296	$	66,486


Ending balance of loans	$	2,003,371	$	1,623,138	$	651,107			$	4,277,616

Ending balance of loans individually evaluated for impairment	$	11,972	$	-	$	-			$	11,972

Ending balance of loans collectively evaluated for impairment	$	1,991,399	$	1,623,138	$	651,107			$	4,265,644

Credit Quality of Loans

Loans are placed on nonaccrual status when timely collection of principal and interest in accordance with contractual terms is doubtful. Loans are transferred to nonaccrual status generally when principal or interest payments become ninety days delinquent, unless the loan is well secured and in the process of collection, or sooner when management concludes or circumstances indicate that borrowers may be unable to meet contractual principal or interest payments. When a loan is transferred to a nonaccrual status, all interest previously accrued in the current period but not collected is reversed against interest income in that period. Interest accrued in a prior period and not collected is charged-off against the allowance for loan losses. The Company’s nonaccrual policies are the same for all classes of financing receivable.

If ultimate repayment of a nonaccrual loan is expected, any payments received are applied in accordance with contractual terms. If ultimate repayment of principal is not expected, any payment received on a nonaccrual loan is applied to principal until ultimate repayment becomes expected. Nonaccrual loans are returned to accrual status when they become current as to principal and interest and demonstrate a period of performance under the contractual terms and, in the opinion of management, are fully collectible as to principal and interest. When in the opinion of management the collection of principal appears unlikely, the loan balance is charged-off in total or in part. For loans in all portfolios, the principal amount is charged off in full or in part as soon as management determines, based on available facts, that the collection of principal in full is improbable. For commercial loans, management considers specific facts and circumstances relative to individual credits in making such a determination. For consumer and residential loan classes, management uses specific guidance and thresholds from the Federal Financial Institutions Examination Council’s Uniform Retail Credit Classification and Account Management Policy.

The following table illustrates the Company’s nonaccrual loans by loan class:

Loans on Nonaccrual Status as of:

(In thousands)	June 30, 2013		December 31, 2012
ORIGINATED
Commercial Loans
Commercial	$	2,622	$	4,985
Commercial Real Estate		10,716		7,977
Agricultural		595		699
Agricultural Real Estate		968		1,038
Business Banking		5,658		6,738
		20,559		21,437

Consumer Loans
Indirect		1,301		1,557
Home Equity		6,583		7,247
Direct		128		266
		8,012		9,070
Residential Real Estate Mortgages		6,414		9,169

	$	34,985	$	39,676

ACQUIRED
Commercial Loans
Commercial	$	446
Commercial Real Estate		-
Business Banking		1,593
		2,039

Consumer Loans
Indirect		139
Home Equity		425
Direct		74
		638

Residential Real Estate Mortgages		2,863

	$	5,540

Total nonaccrual loans	$	40,525	$	39,676

The following tables set forth information with regard to past due and nonperforming loans by loan class as of June 30, 2013 and December 31, 2012:

Age Analysis of Past Due Financing Receivables

As of June 30, 2013

(in thousands)

					Greater Than								Recorded
	31-60 Days		61-90 Days		90 Days		Total						Total
	Past Due		Past Due		Past Due		Past Due						Loans and
	Accruing		Accruing		Accruing		Accruing		Non-Accrual		Current		Leases
ORIGINATED
Commercial Loans
Commercial	$	195	$	20	$	-	$	215	$	2,622	$	583,101	$	585,938
Commercial Real Estate		1,692		-		-		1,692		10,716		875,555		887,963
Agricultural		154		20		-		174		595		63,834		64,603
Agricultural Real Estate		349		-		-		349		968		30,894		32,211
Business Banking		2,176		590		-		2,766		5,658		328,763		337,187
		4,566		630		-		5,196		20,559		1,882,147		1,907,902

Consumer Loans
Indirect		10,749		2,259		832		13,840		1,301		1,033,903		1,049,044
Home Equity		6,475		1,198		704		8,377		6,583		525,429		540,389
Direct		611		210		45		866		128		60,593		61,587
		17,835		3,667		1,581		23,083		8,012		1,619,925		1,651,020
Residential Real Estate Mortgages		487		1,085		358		1,930		6,414		654,548		662,892
	$	22,888	$	5,382	$	1,939	$	30,209	$	34,985	$	4,156,620	$	4,221,814

ACQUIRED
Commercial Loans
Commercial	$	473	$	5	$	-	$	478	$	446	$	137,215	$	138,139
Commercial Real Estate		-		-		-		-		-		242,322		242,322
Agricultural		-		-		-		-		-		25		25
Business Banking		74		-		-		74		1,593		78,842		80,509
		547		5		-		552		2,039		458,404		460,995

Consumer Loans
Indirect		751		162		23		936		139		164,267		165,342
Home Equity		307		754		38		1,099		425		93,370		94,894
Direct		38		30		4		72		74		8,769		8,915
		1,096		946		65		2,107		638		266,406		269,151
Residential Real Estate Mortgages		2,292		230		-		2,522		2,863		333,365		338,750
	$	3,935	$	1,181	$	65	$	5,181	$	5,540	$	1,058,175	$	1,068,896
Total Loans	$	26,823	$	6,563	$	2,004	$	35,390	$	40,525	$	5,214,795	$	5,290,710

As of December 31, 2012

(in thousands)

					Greater Than
	31-60 Days		61-90 Days		90 Days		Total						Recorded
	Past Due		Past Due		Past Due		Past Due						Total
	Accruing		Accruing		Accruing		Accruing		Non-Accrual		Current		Loans
Commercial Loans
Commercial	$	-	$	-	$	-	$	-	$	4,985	$	556,496	$	561,481
Commercial Real Estate		126		-		-		126		7,977		966,692		974,795
Agricultural		22		-		-		22		699		63,037		63,758
Agricultural Real Estate		108		-		103		211		1,038		36,128		37,377
Business Banking		3,019		708		45		3,772		6,738		355,450		365,960
		3,275		708		148		4,131		21,437		1,977,803		2,003,371

Consumer Loans
Indirect		10,956		2,477		1,205		14,638		1,557		964,802		980,997
Home Equity		6,065		1,223		681		7,969		7,247		560,066		575,282
Direct		717		144		84		945		266		65,648		66,859
		17,738		3,844		1,970		23,552		9,070		1,590,516		1,623,138
Residential Real Estate Mortgages		1,839		725		330		2,894		9,169		639,044		651,107
	$	22,852	$	5,277	$	2,448	$	30,577	$	39,676	$	4,207,363	$	4,277,616

There were no material commitments to extend further credit to borrowers with nonperforming loans.

Impaired Loans

The methodology used to establish the allowance for loan losses on impaired loans incorporates specific allocations on loans analyzed individually. Classified loans with outstanding balances of $0.5 million or more are evaluated for impairment through the Company’s quarterly status review process. In determining that we will be unable to collect all principal and interest payments due in accordance with the contractual terms of the loan agreements, we consider factors such as payment history and changes in the financial condition of individual borrowers, local economic conditions, historical loss experience and the conditions of the various markets in which the collateral may be liquidated. For loans that are impaired as defined by accounting standards, impairment is measured by one of three methods: 1) the fair value of collateral less cost to sell, 2) present value of expected future cash flows or 3) the loan’s observable market price. All impaired loans are reviewed on a quarterly basis for changes in the measurement of impairment. Any change to the previously recognized impairment loss is recognized as a change to the allowance account and recorded in the consolidated statement of income as a component of the provision for credit losses.

The following table provides information on impaired loans and specific reserve allocations as of June 30, 2013 and December 31, 2012:

	June 30, 2013						December 31, 2012
	Recorded		Unpaid				Recorded		Unpaid
	Investment		Principal				Investment		Principal
	Balance		Balance		Related		Balance		Balance		Related
(in thousands)	(Book)		(Legal)		Allowance		(Book)		(Legal)		Allowance
With no related allowance recorded:
Commercial Loans
Commercial	$	4,067	$	5,337			$	1,651	$	1,710
Commercial Real Estate		4,347		5,134				8,709		9,553
Agricultural		616		917				940		1,286
Agricultural Real Estate		1,634		1,955				1,713		2,026
Business Banking		7,534		10,213				7,048		9,579
Total Commercial Loans		18,198		23,556				20,061		24,154

Consumer Loans
Home Equity		2,971		3,156				2,553		2,657

Residential Real Estate Mortgages		2,018		2,360				2,011		2,308
	$	23,187	$	29,072			$	24,625	$	29,119

With an allowance recorded:
Commercial Loans
Commercial	$	-	$	-	$	-	$	4,335	$	4,340	$	2,241
Commercial Real Estate		7,302		8,924		2,032		4,068		5,689		607
Agricultural		-		-		-		-		-		-
Agricultural Real Estate		-		-		-		-		-		-
		7,302		8,924		2,032		8,403		10,029		2,848

Total:	$	30,489	$	37,996	$	2,032	$	33,028	$	39,148	$	2,848

The following tables summarize the average recorded investments on impaired loans and the interest income recognized for the three and six months ended June 30, 2013 and 2012:

	For the three months ended
	June 30, 2013				June 30, 2012
	Average		Interest		Average		Interest
	Recorded		Income		Recorded		Income
(in thousands)	Investment		Recognized		Investment		Recognized
Commercial Loans
Commercial	$	2,822	$	15	$	1,128	$	46
Commercial Real Estate		8,616		11		7,140		-
Agricultural		770		-		2,876		5
Agricultural Real Estate		1,123		12		1,876		53
Business Banking		7,843		16		6,572		8
Consumer Loans
Home Equity		2,907		6		1,828		2
Residential Real Estate Mortgages		1,990		15		1,055		-
Total:	$	26,071	$	75	$	22,475	$	114

	For the six months ended
	June 30, 2013				June 30, 2012
	Average		Interest		Average		Interest
	Recorded		Income		Recorded		Income
(in thousands)	Investment		Recognized		Investment		Recognized
Commercial Loans
Commercial	$	4,430	$	30	$	1,551	$	69
Commercial Real Estate		10,614		72		6,481		-
Agricultural		887		3		2,997		36
Agricultural Real Estate		1,482		24		1,926		53
Business Banking		8,016		30		7,151		12
Consumer Loans
Home Equity		2,775		12		1,869		3
Residential Real Estate Mortgages		1,989		27		1,043		-
Total:	$	30,193	$	198	$	23,018	$	173

Credit Quality Indicators

The Company has developed an internal loan grading system to evaluate and quantify the Bank’s loan portfolio with respect to quality and risk. The system focuses on, among other things, financial strength of borrowers, experience and depth of borrower’s management, primary and secondary sources of repayment, payment history, nature of the business, and outlook on particular industries. The internal grading system enables the Company to monitor the quality of the entire loan portfolio on a consistent basis and provide management with an early warning system, enabling recognition and response to problem loans and potential problem loans.

Commercial Grading System

For commercial and agricultural loans, the Company uses a grading system that relies on quantifiable and measurable characteristics when available. This would include comparison of financial strength to available industry averages, comparison of transaction factors (loan terms and conditions) to loan policy, and comparison of credit history to stated repayment terms and industry averages. Some grading factors are necessarily more subjective such as economic and industry factors, regulatory environment, and management. Classified commercial loans consist of loans graded substandard and below. The grading system for commercial and agricultural loans is as follows:

Doubtful

A doubtful loan has a high probability of total or substantial loss, but because of specific pending events that may strengthen the asset, its classification as a loss is deferred. Doubtful borrowers are usually in default, lack adequate liquidity or capital, and lack the resources necessary to remain an operating entity. Pending events can include mergers, acquisitions, liquidations, capital injections, the perfection of liens on additional collateral, the valuation of collateral, and refinancing. Generally, pending events should be resolved within a relatively short period and the ratings will be adjusted based on the new information. Nonaccrual treatment is required for doubtful assets because of the high probability of loss.

Substandard

Substandard loans have a high probability of payment default, or they have other well-defined weaknesses. They require more intensive supervision by bank management. Substandard loans are generally characterized by current or expected unprofitable operations, inadequate debt service coverage, inadequate liquidity, or marginal capitalization. Repayment may depend on collateral or other credit risk mitigants. For some Substandard loans, the likelihood of full collection of interest and principal may be in doubt and those loans should be placed on nonaccrual. Although Substandard assets in the aggregate will have a distinct potential for loss, an individual asset’s loss potential does not have to be distinct for the asset to be rated Substandard.

Special Mention

Special Mention loans have potential weaknesses that may, if not checked or corrected, weaken the asset or inadequately protect the Company’s position at some future date. These loans pose elevated risk, but their weakness does not yet justify a Substandard classification. Borrowers may be experiencing adverse operating trends (declining revenues or margins) or may be struggling with an ill-proportioned balance sheet (e.g., increasing inventory without an increase in sales, high leverage, tight liquidity). Adverse economic or market conditions, such as interest rate increases or the entry of a new competitor, may also support a Special Mention rating. Although a Special Mention loan has a higher probability of default than a pass asset, its default is not imminent.

Pass

Loans graded as Pass encompass all loans not graded as Doubtful, Substandard, or Special Mention. Pass loans are in compliance with loan covenants, and payments are generally made as agreed. Pass loans range from superior quality to fair quality.

Business Banking Grading System

Business banking loans are graded as either Classified or Non-classified:

Classified

Classified loans are inadequately protected by the current worth and paying capacity of the obligor or, if applicable, the collateral pledged. These loans have a well-defined weakness, or weaknesses, that jeopardize the liquidation of the debt, or in some cases make collection or liquidation in full, on the basis of currently existing facts, conditions, and values, highly questionable and improbable. They are characterized by the distinct possibility that the Company will sustain some loss if the deficiencies are not corrected. Classified loans have a high probability of payment default, or a high probability of total or substantial loss. These loans require more intensive supervision by management and are generally characterized by current or expected unprofitable operations, inadequate debt service coverage, inadequate liquidity, or marginal capitalization. Repayment may depend on collateral or other credit risk mitigants. When the likelihood of full collection of interest and principal may be in doubt; classified loans are considered to have a nonaccrual status. In some cases, Classified loans are considered uncollectible and of such little value that their continuance as assets is not warranted.

Non-classified

Loans graded as Non-classified encompass all loans not graded as Classified. Non-classified loans are in compliance with loan covenants, and payments are generally made as agreed.

Consumer and Residential Mortgage Grading System

Consumer and Residential Mortgage loans are graded as either Performing or Nonperforming. Nonperforming loans are loans that are 1) over 90 days past due and interest is still accruing, 2) on nonaccrual status or 3) restructured. All loans not meeting any of these three criteria are considered Performing.

The following tables illustrate the Company’s credit quality by loan class as of June 30, 2013 and December 31, 2012:

Credit Quality Indicators

As of June 30, 2013

ORIGINATED
Commercial Credit Exposure			Commercial				Agricultural
By Internally Assigned Grade:	Commercial		Real Estate		Agricultural		Real Estate		Total
Pass	$	566,686	$	855,687	$	59,026	$	28,722	$	1,510,121
Special Mention		1,899		11,657		78		3		13,637
Substandard		16,850		19,856		5,476		3,486		45,668
Doubtful		503		763		23		-		1,289
Total	$	585,938	$	887,963	$	64,603	$	32,211	$	1,570,715

Business Banking Credit Exposure
By Internally Assigned Grade:	Small Business								Total
Non-classified	$	317,362							$	317,362
Classified		19,825								19,825
Total	$	337,187							$	337,187

Consumer Credit Exposure
By Payment Activity:	Indirect		Home Equity		Direct				Total
Performing	$	1,046,911	$	533,102	$	61,414			$	1,641,427
Nonperforming		2,133		7,287		173				9,593
Total	$	1,049,044	$	540,389	$	61,587			$	1,651,020

Residential Mortgage Credit Exposure	Residential
By Payment Activity:	Mortgage								Total
Performing	$	656,120							$	656,120
Nonperforming		6,772								6,772
Total	$	662,892							$	662,892

Credit Quality Indicators

As of June 30, 2013

ACQUIRED
Commercial Credit Exposure			Commercial
By Internally Assigned Grade:	Commercial		Real Estate		Agricultural		Total
Pass	$	121,901	$	220,131	$	25	$	342,057
Special Mention		8,323		8,822		-		17,145
Substandard		7,915		13,369		-		21,284
Doubtful		-		-		-		-
Total	$	138,139	$	242,322	$	25	$	380,486

Business Banking Credit Exposure
By Internally Assigned Grade:	Small Business						Total
Non-classified	$	75,418					$	75,418
Classified		5,091						5,091
Total	$	80,509					$	80,509

Consumer Credit Exposure
By Payment Activity:	Indirect		Home Equity		Direct		Total
Performing	$	165,180	$	94,006	$	8,763	$	267,949
Nonperforming		162		888		152		1,202
Total	$	165,342	$	94,894	$	8,915	$	269,151

Residential Mortgage Credit Exposure	Residential
By Payment Activity:	Mortgage						Total
Performing	$	335,887					$	335,887
Nonperforming		2,863						2,863
Total	$	338,750					$	338,750

Credit Quality Indicators

As of December 31, 2012

Commercial Credit Exposure			Commercial				Agricultural
By Internally Assigned Grade:	Commercial		Real Estate		Agricultural		Real Estate		Total
Pass	$	522,985	$	901,928	$	57,347	$	33,472	$	1,515,732
Special Mention		18,401		32,135		13		3		50,552
Substandard		17,351		40,732		6,362		3,902		68,347
Doubtful		2,744		-		36		-		2,780
Total	$	561,481	$	974,795	$	63,758	$	37,377	$	1,637,411

Business Banking. Credit Exposure
By Internally Assigned Grade:	Small Business								Total
Non-classified	$	342,528							$	342,528
Classified		23,432								23,432
Total	$	365,960							$	365,960

Consumer Credit Exposure
By Payment Activity:	Indirect		Home Equity		Direct				Total
Performing	$	978,235	$	567,354	$	66,509			$	1,612,098
Nonperforming		2,762		7,928		350				11,040
Total	$	980,997	$	575,282	$	66,859			$	1,623,138

Residential Mortgage Credit Exposure	Residential
By Payment Activity:	Mortgage								Total
Performing	$	641,608							$	641,608
Nonperforming		9,499								9,499
Total	$	651,107							$	651,107

Troubled Debt Restructured Loans

The Company’s loan portfolio includes certain loans that have been modified where economic concessions have been granted to borrowers who have experienced or are expected to experience financial difficulties. These concessions typically result from the Company’s loss mitigation activities and could include reductions in the interest rate, payment extensions, forgiveness of principal, forbearance or other actions. Certain troubled debt restructured loans (“TDRs”) are classified as nonperforming at the time of restructure and may only be returned to performing status after considering the borrower’s sustained repayment performance for a reasonable period, generally six months.

When the Company modifies a loan, management evaluates any possible impairment based on the present value of the expected future cash flows, discounted at the contractual interest rate of the original loan agreement, except when the sole (remaining) source of repayment for the loan is the operation or liquidation of the collateral. In these cases, management uses the current fair value of the collateral, less selling costs, instead of discounted cash flows. If management determines that the value of the modified loan is less than the recorded investment in the loan (net of previous charge-offs, deferred loan fees or costs and unamortized premium or discount), impairment is recognized by segment or class of loan as applicable, through an allowance estimate or a charge-off to the allowance. Segment and class status is determined by the loan’s classification at origination.

TDRs that occurred during the three month period ending June 30, 2013 consisted of 10 home equity loans, one residential real estate mortgage, and one commercial real estate loan totaling $0.5 million, $0.1 million, and $0.9 million, respectively. For all such modifications, the pre and post outstanding recorded investment amount remained unchanged. During the three month period ending June 30, 2013 there were three defaults on home equity loans totaling $0.2 million.

TDRs that occurred during the three month period ending June 30, 2012 consisted of 1 commercial loan totaling $1.0 million. The pre and post outstanding recorded investment amount remained unchanged. During the three month period ending June 30, 2012 there was one default on a home equity loan and three defaults on residential real estate mortgages totaling $25,000 and $0.4 million, respectively, on previously modified loans.

TDRs that occurred during the six month period ending June 30, 2013 consisted of 14 home equity loans, one residential real estate mortgage, and one commercial real estate loan totaling $0.6 million, $0.1 million, and $0.9 million, respectively. For all such modifications, the pre and post outstanding recorded investment amount remained unchanged. During the six month period ending June 30, 2013 there were three defaults on home equity loans totaling $0.2 million.

TDRs that occurred during the six month period ending June 30, 2012 consisted of 1 commercial loan totaling $1.0 million and one residential real estate mortgage totaling $0.2 million. The pre and post outstanding recorded investment amount remained unchanged. During the six month period ending June 30, 2012 there was one default on a home equity loan totaling $25,000 that was previously modified.

Earnings Per Share

6 Months Ended

Jun. 30, 2013

Earnings Per Share [Abstract]

Earnings Per Share

Note 6.

Earnings Per Share

Basic earnings per share excludes dilution and is computed by dividing income available to common stockholders by the weighted average number of common shares outstanding for the period. Diluted earnings per share reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in the earnings of the entity (such as the Company’s dilutive stock options and restricted stock units).

The following is a reconciliation of basic and diluted earnings per share for the periods presented in the consolidated statements of income.

Three months ended June 30,	2013		2012
(in thousands, except per share data)
Basic EPS:
Weighted average common shares outstanding		43,923		33,191
Net income available to common shareholders		16,916		13,257
Basic EPS	$	0.39	$	0.40
Diluted EPS:
Weighted average common shares outstanding		43,923		33,191
Dilutive effect of common stock options and restricted stock		393		301
Weighted average common shares and common share equivalents		44,316		33,492
Net income available to common shareholders		16,916		13,257
Diluted EPS	$	0.38	$	0.40

Six months ended June 30,		2013		2012
(in thousands, except per share data)
Basic EPS:
Weighted average common shares outstanding		40,187		33,128
Net income available to common shareholders		24,565		26,907
Basic EPS	$	0.61	$	0.81
Diluted EPS:
Weighted average common shares outstanding		40,187		33,128
Dilutive effect of common stock options and restricted stock		388		325
Weighted average common shares and common share equivalents		40,575		33,453
Net income available to common shareholders		24,565		26,907
Diluted EPS	$	0.61	$	0.80

There were 1,231,395 stock options for the quarter ended June 30, 2013 and 1,271,116 stock options for the quarter ended June 30, 2012 that were not considered in the calculation of diluted earnings per share since the stock options’ exercise price was greater than the average market price during these periods.

There were 1,203,046 stock options for the six months ended June 30, 2013 and 1,209,201 stock options for the six months ended June 30, 2012 that were not considered in the calculation of diluted earnings per share since the stock options’ exercise price was greater than the average market price during these periods.

Defined Benefit Postretirement Plans

6 Months Ended

Jun. 30, 2013

Defined Benefit Postretirement Plans [Abstract]

Defined Benefit Postretirement Plans

Note 7.

Defined Benefit Postretirement Plans

The Company has a qualified, noncontributory, defined benefit pension plan covering substantially all of its employees at June 30, 2013, including eligible Alliance employees as of March 8, 2013. Benefits paid from the plan are based on age, years of service, compensation and social security benefits, and are determined in accordance with defined formulas. The Company’s policy is to fund the pension plan in accordance with Employee Retirement Income Security Act of 1974 (“ERISA”) standards. Assets of the plan are invested in publicly traded stocks and bonds.

The Company assumed a noncontributory, defined benefit pension plan in the Alliance acquisition. The plan covers certain Alliance full-time employees who met eligibility requirements on October 6, 2006, at which time all benefits were frozen. Under the plan, retirement benefits are primarily a function of both the years of service and the level of compensation. The Company is not required to make contributions to the plans in 2013, and did not do so during the six months ended June 30, 2013. Effective May 1, 2013, this plan was merged into the NBT Bancorp Inc. Defined Benefit Pension Plan. The merging of the plans did not have a significant impact on the Company’s financial statements and related footnotes.

In addition to the pension plans, the Company also provides supplemental employee retirement plans to certain current and former executives. These supplemental employee retirement plans and the defined benefit pension plans are collectively referred to herein as “Pension Benefits.”

Also, the Company provides certain health care benefits for retired employees. Benefits are accrued over the employees’ active service period. Only employees that were employed by the Company on or before January 1, 2000 are eligible to receive postretirement health care benefits. The plan is contributory for participating retirees, requiring participants to absorb certain deductibles and coinsurance amounts with contributions adjusted annually to reflect cost sharing provisions and benefit limitations called for in the plan. Eligibility is contingent upon the direct transition from active employment status to retirement without any break in employment from the Company. Employees also must be participants in the Company’s medical plan prior to their retirement. The Company funds the cost of postretirement health care as benefits are paid. The Company elected to recognize the transition obligation on a delayed basis over twenty years. In addition, the Company assumed post-retirement medical life insurance benefits for certain Alliance employees, retirees and their spouses, if applicable, in the Alliance acquisition. These postretirement benefits are referred to herein as “Other Benefits.” The components of expense for Pension Benefits and Other Benefits are set forth below (in thousands):

	Pension Benefits							Other Benefits
	Three months ended June 30,							Three months ended June 30,
Components of net periodic benefit cost:	2013				2012			2013				2012
Service cost		$	604		$	757			$	6		$	5
Interest cost			830			774				75			40
Expected return on plan assets			(1,929	)		(1,675	)			-			-
Net amortization			711			859				(1	)		(3	)
Total cost (benefit)		$	216		$	715			$	80		$	42

	Pension Benefits							Other Benefits
	Six months ended June 30,							Six months ended June 30,
Components of net periodic benefit cost:		2013			2012				2013			2012
Service cost		$	1,209		$	1,513			$	12		$	10
Interest cost			1,659			1,548				150			79
Expected return on plan assets			(3,858	)		(3,350	)			-			-
Net amortization			1,314			1,718				222			(5	)
Total cost (benefit)		$	324		$	1,429			$	384		$	84

The Company is not required to make contributions to the plans in 2013, and did not do so during the six months ended June 30, 2013.

Market conditions can result in an unusually high degree of volatility and increase the risks and short term liquidity associated with certain investments held by the Company’s defined benefit pension plan (“the Plan”) which could impact the value of these investments.

Trust Preferred Debentures

6 Months Ended

Jun. 30, 2013

Trust Preferred Debentures [Abstract]

Trust Preferred Debentures

Note 8.

Trust Preferred Debentures

The Company sponsors five business trusts, CNBF Capital Trust I, NBT Statutory Trust I, NBT Statutory Trust II, Alliance Financial Capital Trust I and Alliance Financial Capital Trust II. The trusts were formed for the purpose of issuing company-obligated mandatorily redeemable preferred securities to third-party investors and investing in the proceeds from the sale of such preferred securities solely in junior subordinated debt securities of the Company. The debentures held by each trust are the sole assets of that trust. These five statutory business trusts are collectively referred herein to as “the Trusts.” The Company guarantees, on a limited basis, payments of distributions on the trust preferred securities and payments on redemption of the trust preferred securities. The Trusts are variable interest entities (“VIEs”) for which the Company is not the primary beneficiary, as defined by U.S. GAAP. In accordance with U.S. GAAP, the accounts of the Trusts are not included in the Company’s consolidated financial statements.

As of June 30, 2013, the Trusts had the following issues of trust preferred debentures, all held by the Trusts, outstanding (dollars in thousands):

Description	Issuance Date	Trust Preferred Securities Outstanding		Interest Rate	Trust Preferred Debt Owed To Trust		Final Maturity Date

CNBF Capital Trust I	August-99	$	18,000	3-month LIBOR plus 2.75%	$	18,720	August-29

NBT Statutory Trust I	November-05		5,000	3-month LIBOR plus 1.40%		5,155	December-35

NBT Statutory Trust II	February-06		50,000	3-month LIBOR plus 1.40%		51,547	March-36

Alliance Financial Capital Trust I	December-03		10,000	3-month LIBOR plus 2.85%		10,310	January-34

Alliance Financial Capital Trust II	September-06		15,000	3-month LIBOR plus 1.65%		15,464	September-36

The Company owns all of the common stock of the Trusts, which have issued trust preferred securities in conjunction with the Company issuing trust preferred debentures to the Trusts. The terms of the trust preferred debentures are substantially the same as the terms of the trust preferred securities.

Fair Values Measurements and Fair Value of Financial Instruments

6 Months Ended

Jun. 30, 2013

Fair Value Measurements and Fair Value of Financial Instruments [Abstract]

Fair Value Measurements and Fair Value of Financial Instruments

Note 9.

Fair Value Measurements and Fair Value of Financial Instruments

U.S. GAAP states that fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value measurements are not adjusted for transaction costs. A fair value hierarchy exists within U.S. GAAP that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (level 1 measurements) and the lowest priority to unobservable inputs (level 3 measurements). The three levels of the fair value hierarchy are described below:

Level 1 - Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;

Level 2 - Quoted prices for similar assets or liabilities in active markets, quoted prices in markets that are not active, or inputs that are observable, either directly or indirectly, for substantially the full term of the asset or liability;

Level 3 - Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity).

A financial instrument’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement.

The types of instruments valued based on quoted market prices in active markets include most U.S. government and agency securities, many other sovereign government obligations, liquid mortgage products, active listed equities and most money market securities. Such instruments are generally classified within level 1 or level 2 of the fair value hierarchy. The Company does not adjust the quoted price for such instruments.

The types of instruments valued based on quoted prices in markets that are not active, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency include most investment-grade and high-yield corporate bonds, less liquid mortgage products, less liquid agency securities, less liquid listed equities, state, municipal and provincial obligations, and certain physical commodities. Such instruments are generally classified within level 2 of the fair value hierarchy.

Level 3 is for positions that are not traded in active markets or are subject to transfer restrictions, valuations are adjusted to reflect illiquidity and/or non-transferability, and such adjustments are generally based on available market evidence. In the absence of such evidence, management’s best estimate will be used. Management’s best estimate consists of both internal and external support on certain Level 3 investments. Subsequent to inception, management only changes level 3 inputs and assumptions when corroborated by evidence such as transactions in similar instruments, completed or pending third-party transactions in the underlying investment or comparable entities, subsequent rounds of financing, recapitalizations and other transactions across the capital structure, offerings in the equity or debt markets, and changes in financial ratios or cash flows.

For the six month period ending June 30, 2013, the Company has made no transfers of assets between Level 1 and Level 2, and has had no Level 3 activity.

The following tables set forth the Company’s financial assets and liabilities measured on a recurring basis that were accounted for at fair value. Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement (in thousands):

June 30, 2013:

	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable		Balance
	Identical Assets		Inputs		Inputs		as of
	(Level 1)		(Level 2)		(Level 3)		June 30, 2013
Assets:
Securities Available for Sale:
U.S. Treasury	$	53,949	$	-	$	-	$	53,949
Federal Agency		-		279,458		-		279,458
State & municipal		-		126,674		-		126,674
Mortgage-backed		-		291,594		-		291,594
Collateralized mortgage obligations		-		622,768		-		622,768
Other securities		10,909		5,051		-		15,960
Total Securities Available for Sale	$	64,858	$	1,325,545	$	-	$	1,390,403
Trading Securities		5,092		-		-		5,092
Interest Rate Swaps		-		68		-		68
Total	$	69,950	$	1,325,613	$	-	$	1,395,563

Liabilities:
Interest Rate Swaps	$	-	$	68	$	-	$	68
Total	$	-	$	68	$	-	$	68

December 31, 2012:

	Quoted Prices in		Significant		Significant
	Active Markets for		Other		Unobservable		Balance
	Identical Assets		Observable Inputs		Inputs		as of
	(Level 1)		(Level 2)		(Level 3)		December 31, 2012
Assets:
Securities Available for Sale:
U.S. Treasury	$	64,425	$	-	$	-	$	64,425
Federal Agency		-		282,814		-		282,814
State & municipal		-		86,802		-		86,802
Mortgage-backed		-		250,281		-		250,281
Collateralized mortgage obligations		-		449,723		-		449,723
Other securities		11,866		2,088		-		13,954
Total Securities Available for Sale	$	76,291	$	1,071,708	$	-	$	1,147,999
Trading Securities		3,918		-		-		3,918
Interest Rate Swaps		-		1,490		-		1,490
Total	$	80,209	$	1,073,198	$	-	$	1,153,407

Liabilities:
Interest Rate Swaps	$	-	$	1,490	$	-	$	1,490
Total	$	-	$	1,490	$	-	$	1,490

Certain common equity securities are reported at fair value utilizing Level 1 inputs (exchange quoted prices). The majority of the other investment securities are reported at fair value utilizing Level 2 inputs. The prices for these instruments are obtained through an independent pricing service or dealer market participants with whom the Company has historically transacted both purchases and sales of investment securities. Prices obtained from these sources include prices derived from market quotations and matrix pricing. The fair value measurements consider observable data that may include dealer quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the bond’s terms and conditions, among other things. Management reviews the methodologies used in pricing the securities by its third party providers.

U.S. GAAP requires disclosure of assets and liabilities measured and recorded at fair value on a nonrecurring basis such as goodwill, loans held for sale, other real estate owned, collateral-dependent impaired loans, mortgage servicing rights, and held-to-maturity securities. The only nonrecurring fair value measurement recorded during the six month period ended June 30, 2013 and December 31, 2012 was related to impaired loans. The Company had collateral dependent impaired loans with a carrying value of approximately $7.3 million which had specific reserves included in the allowance for loan losses of $2.0 million at June 30, 2013. The Company had collateral dependent impaired loans with a carrying value of approximately $8.4 million which had specific reserves included in the allowance for loan losses of $2.8 million at December 31, 2012. The Company uses the fair value of underlying collateral, less costs to sell, to estimate the specific reserves for collateral dependent impaired loans. The appraisals may be adjusted by management for qualitative factors such as economic conditions and estimated liquidation expenses ranging from 10% to 35%. Based on the valuation techniques used, the fair value measurements for collateral dependent impaired loans are classified as Level 3.

The following table sets forth information with regard to estimated fair values of financial instruments at June 30, 2013 and December 31, 2012. This table excludes financial instruments for which the carrying amount approximates fair value. Financial instruments for which the fair value approximates carrying value include cash and cash equivalents, securities available for sale, trading securities, accrued interest receivable, non-maturity deposits, short-term borrowings, accrued interest payable, and interest rate swaps.

			June 30, 2013				December 31, 2012
(In thousands)	Fair Value Hierarchy		Carrying amount		Estimated fair value		Carrying amount		Estimated fair value
Financial assets
Securities held to maturity		2	$	122,302	$	121,069	$	60,563	$	61,535
Net loans		3		5,219,526		5,287,651		4,208,282		4,313,244
Financial liabilities
Time deposits		2	$	1,105,038	$	1,112,212	$	983,261	$	994,376
Long-term debt		2		309,111		336,980		367,492		407,404
Trust preferred debentures		2		101,196		100,460		75,422		74,147

Fair value estimates are made at a specific point in time, based on relevant market information and information about the financial instrument. These estimates do not reflect any premium or discount that could result from offering for sale at one time the Company’s entire holdings of a particular financial instrument. Because no market exists for a significant portion of the Company’s financial instruments, fair value estimates are based on judgments regarding future expected loss experience, current economic conditions, risk characteristics of various financial instruments, and other factors. These estimates are subjective in nature and involve uncertainties and matters of significant judgment and therefore cannot be determined with precision. Changes in assumptions could significantly affect the estimates.

Fair value estimates are based on existing on and off balance sheet financial instruments without attempting to estimate the value of anticipated future business and the value of assets and liabilities that are not considered financial instruments. For example, the Company has a substantial trust and investment management operation that contributes net fee income annually. The trust and investment management operation is not considered a financial instrument, and its value has not been incorporated into the fair value estimates. Other significant assets and liabilities include the benefits resulting from the low-cost funding of deposit liabilities as compared to the cost of borrowing funds in the market, and premises and equipment. In addition, the tax ramifications related to the realization of the unrealized gains and losses can have a significant effect on fair value estimates and have not been considered in the estimate of fair value.

Securities Held to Maturity

The fair value of the Company’s investment securities held to maturity is primarily measured using information from a third party pricing service. The fair value measurements consider observable data that may include dealer quotes, market spreads, cash flows, the U.S. Treasury yield curve, live trading levels, trade execution data, market consensus prepayment speeds, credit information and the bond’s terms and conditions, among other things.

Net Loans

The fair value of the Company’s loans was estimated by discounting the expected future cash flows using the current interest rates at which similar loans would be made for the same remaining maturities. Loans were first segregated by type, and then further segmented into fixed and variable rate and loan quality categories. Expected future cash flows were projected based on contractual cash flows, adjusted for estimated prepayments.

Time Deposits

The fair value of time deposits was estimated using a discounted cash flow approach that applies prevailing market interest rates for similar maturity instruments. The fair values of the Company’s time deposit liabilities do not take into consideration the value of the Company’s long-term relationships with depositors, which may have significant value.

Long-Term Debt

The fair value of long-term debt was estimated using a discounted cash flow approach that applies prevailing market interest rates for similar maturity instruments.

Trust Preferred Debentures

The fair value of trust preferred debentures has been estimated using a discounted cash flow analysis.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Securities

6 Months Ended

Jun. 30, 2013

Securities [Abstract]

Securities

Note 10.

Securities

The amortized cost, estimated fair value, and unrealized gains and losses of securities available for sale are as follows:

(In thousands)	Amortized cost		Unrealized gains		Unrealized losses		Estimated fair value
June 30, 2013
U.S. Treasury	$	53,440	$	509	$	-	$	53,949
Federal Agency		286,049		192		6,783		279,458
State & municipal		125,792		2,375		1,493		126,674
Mortgage-backed:
Government-sponsored enterprises		260,130		6,149		1,487		264,792
U.S. government securities		25,608		1,269		75		26,802
Collateralized mortgage obligations:
Government-sponsored enterprises		573,487		2,677		6,747		569,417
U.S. government securities		52,421		970		40		53,351
Other securities		13,409		2,720		169		15,960
Total securities available for sale	$	1,390,336	$	16,861	$	16,794	$	1,390,403
December 31, 2012
U.S. Treasury	$	63,668	$	757	$	-	$	64,425
Federal Agency		281,398		1,507		91		282,814
State & municipal		82,675		4,127		-		86,802
Mortgage-backed:
Government-sponsored enterprises		221,110		11,175		-		232,285
U.S. government securities		16,351		1,645		-		17,996
Collateralized mortgage obligations:
Government-sponsored enterprises		399,147		4,418		-		403,565
U.S. government securities		44,825		1,333		-		46,158
Other securities		11,210		2,832		88		13,954
Total securities available for sale	$	1,120,384	$	27,794	$	179	$	1,147,999

Other securities primarily represent marketable equity securities.

Proceeds from the sales of securities available for sale were $26.2 million during the six months ended June 30, 2013, and gains on the sales were $1.1 million. Proceeds from the sales of securities available for sale were $1.8 million during the six months ended June 30, 2012, and gains on the sales were $0.6 million.

Securities with amortized costs totaling $1.5 billion at June 30, 2013 and $1.2 billion at December 31, 2012, were pledged to secure public deposits and for other purposes required or permitted by law. Additionally, at June 30, 2013 and December 31, 2012, securities available for sale with an amortized cost of $224.6 million and $209.0 million, respectively, were pledged as collateral for securities sold under repurchase agreements.

The amortized cost, estimated fair value, and unrealized gains and losses of securities held to maturity are as follows:

	Amortized		Unrealized		Unrealized		Estimated
(In thousands)	cost		gains		losses		fair value
June 30, 2013
Mortgage-backed	$	1,070	$	151	$	-	$	1,221
Collateralized mortgage oblications		64,022		-		1,964		62,058
State & municipal		57,210		580		-		57,790
Total securities held to maturity	$	122,302	$	731	$	1,964	$	121,069
December 31, 2012
Mortgage-backed	$	1,168	$	184	$	-	$	1,352
Collateralized mortgage oblications		-		-		-		0
State & municipal		59,395		788		-		60,183
Total securities held to maturity	$	60,563	$	972	$	-	$	61,535

The following table sets forth information with regard to investment securities with unrealized losses at June 30, 2013 and December 31, 2012:

	Less than 12 months							12 months or longer							Total
Security Type:	Fair Value		Unrealized losses			Number of Positions		Fair Value		Unrealized losses			Number of Positions		Fair Value		Unrealized losses			Number of Positions

June 30, 2013
Investment securities available for sale:
U.S. Treasury	$	-	$	-			-	$	-	$	-			-	$	-	$	-			-
Federal agency		286,049		(6,783	)		20		-		-			-		286,049		(6,783	)		20
State & municipal		125,792		(1,493	)		193		-		-			-		125,792		(1,493	)		193
Mortgage-backed		285,687		(1,562	)		94		-		-			-		285,687		(1,562	)		94
Collateralized mortgage obligations		625,908		(6,787	)		28		-		-			-		625,908		(6,787	)		28
Other securities		5,560		(132	)		2		211		(37	)		1		5,771		(169	)		3
Total securities with unrealized losses	$	1,328,996	$	(16,757	)		337	$	211	$	(37	)		1	$	1,329,207	$	(16,794	)		338

June 30, 2013
Investment securities held to maturity:
Collateralized mortgage obligations		64,022		(1,964	)		5		-		-			-		64,022		(1,964	)		5
Total securities with unrealized losses	$	64,022	$	(1,964	)		5	$	-	$	-			-	$	64,022	$	(1,964	)		5

	Less than 12 months							12 months or longer							Total
	Fair Value		Unrealized losses			Number of Positions		Fair Value		Unrealized losses			Number of Positions		Fair Value		Unrealized losses			Number of Positions
December 31, 2012
Investment securities available for sale:
U.S. Treasury	$	-	$	-			-	$	-	$	-			-	$	-	$	-			-
Federal agency		39,906		(91	)		4		-		-			-		39,906		(91	)		4
State & municipal		-		-			-		-		-			-		-		-			-
Mortgage-backed		-		-			-		-		-			-		-		-			-
Collateralized mortgage obligations		23		-			2		-		-			-		23		-			2
Other securities		468		(6	)		1		167		(82	)		1		635		(88	)		2
Total securities with unrealized losses	$	40,397	$	(97	)		7	$	167	$	(82	)		1	$	40,564	$	(179	)		8

Declines in the fair value of held-to-maturity and available-for-sale securities below their cost that are deemed to be other than temporary are reflected in earnings as realized losses or in other comprehensive income, depending on whether the Company intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss. If the Company intends to sell the security or more likely than not will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss, the other-than-temporary impairment shall be recognized in earnings equal to the entire difference between the investment’s amortized cost basis and its fair value at the balance sheet date. If the Company does not intend to sell the security and it is not more likely than not that the entity will be required to sell the security before recovery of its amortized cost basis less any current-period credit loss, the other-than-temporary impairment shall be separated into (a) the amount representing the credit loss and (b) the amount related to all other factors. The amount of the total other-than-temporary impairment related to the credit loss shall be recognized in earnings. The amount of the total other-than-temporary impairment related to other factors shall be recognized in other comprehensive income, net of applicable taxes.

In estimating other-than-temporary impairment losses, management considers, among other things, (i) the length of time and the extent to which the fair value has been less than cost, (ii) the financial condition and near-term prospects of the issuer, and (iii) the historical and implied volatility of the fair value of the security.

Management has the intent to hold the securities classified as held to maturity until they mature, at which time it is believed the Company will receive full value for the securities. Furthermore, as of June 30, 2013, management also had the intent to hold, and will not be required to sell, the securities classified as available for sale for a period of time sufficient for a recovery of cost, which may be until maturity. The unrealized losses are due to increases in market interest rates over the yields available at the time the underlying securities were purchased. When necessary, the Company has performed a discounted cash flow analysis to determine whether or not it will receive the contractual principal and interest on certain securities. The fair value is expected to recover as the bonds approach their maturity date or repricing date or if market yields for such investments decline. As of June 30, 2013, management believes the impairments detailed in the table above are temporary and no other-than-temporary impairment losses have been realized in the Company’s consolidated statements of income.

The following tables set forth information with regard to contractual maturities of debt securities at June 30, 2013:

(In thousands)	Amortized cost		Estimated fair value
Debt securities classified as available for sale
Within one year	$	26,789	$	26,915
From one to five years		194,833		195,558
From five to ten years		348,099		345,525
After ten years		807,206		806,445
	$	1,376,927	$	1,374,443
Debt securities classified as held to maturity
Within one year	$	25,315	$	25,415
From one to five years		24,620		25,095
From five to ten years		5,651		5,656
After ten years		66,716		64,903
	$	122,302	$	121,069

Maturities of mortgage-backed, collateralized mortgage obligations and asset-backed securities are stated based on their estimated average lives. Actual maturities may differ from estimated average lives or contractual maturities because, in certain cases, borrowers have the right to call or prepay obligations with or without call or prepayment penalties.

Except for U.S. Government securities, there were no holdings, when taken in the aggregate, of any single issuer that exceeded 10% of consolidated stockholders’ equity at June 30, 2013.

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References + Details

Reclassification Adjustments Out of Other Comprehensive (Loss) Income

6 Months Ended

Jun. 30, 2013

Reclassification Adjustments Out of Other Comprehensive Loss income [Abstract]

Reclassification Adjustments Out of Other Comprehensive (Loss) Income

Note 11.

Reclassification Adjustments Out of Other Comprehensive (Loss) Income

The following table summarizes the reclassification adjustments out of accumulated other comprehensive loss (in thousands):

Detail About Accumulated Other Comprehensive (Loss) Income Components	Amount reclassified from accumulated other comprehensive income (loss)						Affected line item in the consolidated statement of comprehensive income
	Three months ended
	June 30, 2013			June 30, 2012
Available for sale securities:
Unrealized losses (gains) on available for sale securities	$	61		$	(97	)	Net securities gains
Tax (benefit) expense		(24	)		39		Income tax expense
Net of tax	$	37		$	(58	)

Pension and other benefits:
Amortization of net gains	$	765		$	911		Salaries and employee benefits
Amortization of prior service costs		(55	)		(55	)	Salaries and employee benefits
Tax benefit		284			345		Income tax expense
Net of tax	$	426		$	511

Total reclassifications during the period, net of tax	$	463		$	453

Detail About Accumulated Other Comprehensive (Loss) Income Components	Amount reclassified from accumulated other comprehensive income (loss)						Affected line item in the consolidated statement of comprehensive income
	Six months ended
	June 30, 2013			June 30, 2012
Available for sale securities:
Unrealized gains on available for sale securities	$	(1,084	)	$	(552	)	Net securities gains
Tax expense		434			221		Income tax expense
Net of tax	$	(650	)	$	(331	)

Pension and other benefits:
Amortization of net gains	$	1,647		$	1,824		Salaries and employee benefits
Amortization of prior service costs		(111	)		(111	)	Salaries and employee benefits
Tax benefit		614			686		Income tax expense
Net of tax	$	922		$	1,027

Total reclassifications during the period, net of tax	$	272		$	696

Acquisition (Tables)

6 Months Ended

Jun. 30, 2013

Acquisition [Abstract]

Consideration paid, assets acquired, and liabilities assumed

Consideration paid:
NBT Bancorp common stock issued to Alliance common shareholders	$	225,551
Cash in lieu of fractional shares paid to Alliance common shareholders		11
Less treasury shares		5,779

Net consideration paid	$	219,783

Recognized Amounts of Identifiable Assets Acquired and (Liabilities Assumed) At Fair Value:
Cash and short term investments	$	81,060
Securities		320,618
Loans		904,473
Intangible assets		13,161
Other assets		71,823
Deposits		(1,113,420	)
Borrowings		(126,530	)
Trust preferred debentures		(25,774	)
Other liabilities		(18,466	)
Total identifiable net assets	$	106,945

Goodwill	$	112,838

Acquired loan portfolio

Information about the acquired loan portfolio as of March 8, 2013 is as follows (in thousands):

Contractually required principal and interest at acquisition	$	908,614
Contractual cash flows not expected to be collected		(15,466	)
Expected cash flows at acquisition		893,148
Interest component of expected cash flows (accretable premium)		11,325
Fair value of acquired loans	$	904,473

Schedule of changes in accretable discount

The following table presents changes in the accretable discount (in thousands):

Balance at January 1, 2013	$	-
Alliance acquisition		11,325
Accretion recognized to date		(994	)
Balance at June 30, 2013	$	10,331

Schedule of unaudited pro forma amounts related to acquisition

	Pro forma
	Six months ended June 30,
	2013		2012

Net interest income	$	120,593	$	119,471
Noninterest income		55,445		52,738
Net income		33,911		32,104

Allowance for Loan Losses and Credit Quality of Loans (Tables)

6 Months Ended

Jun. 30, 2013

Allowance for Loan Losses and Credit Quality of Loans [Abstract]

Allowance for loan losses by portfolio

The following tables illustrate the changes in the allowance for loan losses by our portfolio segments for the three and six months ended June 30, 2013 and 2012:

							Residential
Three months ended June 30	Commercial			Consumer			Real Estate
	Loans			Loans			Mortgages			Unallocated			Total
Balance as of March 31, 2013	$	35,358		$	26,285		$	6,708		$	383		$	68,734
Charge-offs		(1,198	)		(3,653	)		(302	)		-			(5,153	)
Recoveries		416			696			89			-			1,201
Provision		3,128			3,128			311			(165	)		6,402
Ending Balance as of June 30, 2013	$	37,704		$	26,456		$	6,806		$	218		$	71,184

Balance as of March 31, 2012	$	37,787		$	26,790		$	6,520		$	237		$	71,334
Charge-offs		(1,653	)		(3,735	)		(292	)		-			(5,680	)
Recoveries		303			667			7			-			977
Provision		1,058			3,513			(292	)		(176	)		4,103
Ending Balance as of June 30, 2012	$	37,495		$	27,235		$	5,943		$	61		$	70,734

							Residential
Six months ended June 30	Commercial			Consumer			Real Estate
	Loans			Loans			Mortgages			Unallocated			Total
Balance as of December 31, 2012	$	35,624		$	27,162		$	6,252		$	296		$	69,334
Charge-offs		(4,520	)		(7,376	)		(973	)		-			(12,869	)
Recoveries		883			1,673			103			-			2,659
Provision		5,717			4,997			1,424			(78	)		12,060
Ending Balance as of June 30, 2013	$	37,704		$	26,456		$	6,806		$	218		$	71,184

Balance as of December 31, 2011	$	38,831		$	26,049		$	6,249		$	205		$	71,334
Charge-offs		(2,783	)		(7,787	)		(650	)		-			(11,220	)
Recoveries		688			1,342			16			-			2,046
Provision		759			7,631			328			(144	)		8,574
Ending Balance as of June 30, 2012	$	37,495		$	27,235		$	5,943		$	61		$	70,734

The following tables illustrate the allowance for loan losses and the recorded investment by portfolio segments as of June 30, 2013 and December 31, 2012:

Allowance for Loan Losses and Recorded Investment in Loans
(in thousands)

					Residential
	Commercial		Consumer		Real Estate
	Loans		Loans		Mortgages		Unallocated		Total
As of June 30, 2013
Allowance for loan losses	$	37,704	$	26,456	$	6,806	$	218	$	71,184

Allowance for loans individually evaluated for impairment	$	2,032	$	-	$	-			$	2,032

Allowance for loans collectively evaluated for impairment	$	35,672	$	26,456	$	6,806	$	218	$	69,152

Ending balance of loans	$	2,368,897	$	1,920,171	$	1,001,642			$	5,290,710

Ending balance of loans individually evaluated for impairment	$	12,887	$	-	$	-			$	12,887
Ending balance of acquired loans	$	460,995	$	269,151	$	338,750			$	1,068,896
Ending balance of loans collectively evaluated for impairment	$	1,895,015	$	1,651,020	$	662,892			$	4,208,927

As of December 31, 2012
Allowance for loan losses	$	35,624	$	27,162	$	6,252	$	296	$	69,334

Allowance for loans individually evaluated for impairment	$	2,848	$	-	$	-			$	2,848

Allowance for loans collectively evaluated for impairment	$	32,776	$	27,162	$	6,252	$	296	$	66,486


Ending balance of loans	$	2,003,371	$	1,623,138	$	651,107			$	4,277,616

Ending balance of loans individually evaluated for impairment	$	11,972	$	-	$	-			$	11,972

Ending balance of loans collectively evaluated for impairment	$	1,991,399	$	1,623,138	$	651,107			$	4,265,644

Past due and nonperforming loans by loan class

The following table illustrates the Company’s nonaccrual loans by loan class:

Loans on Nonaccrual Status as of:

(In thousands)	June 30, 2013		December 31, 2012
ORIGINATED
Commercial Loans
Commercial	$	2,622	$	4,985
Commercial Real Estate		10,716		7,977
Agricultural		595		699
Agricultural Real Estate		968		1,038
Business Banking		5,658		6,738
		20,559		21,437

Consumer Loans
Indirect		1,301		1,557
Home Equity		6,583		7,247
Direct		128		266
		8,012		9,070
Residential Real Estate Mortgages		6,414		9,169

	$	34,985	$	39,676

ACQUIRED
Commercial Loans
Commercial	$	446
Commercial Real Estate		-
Business Banking		1,593
		2,039

Consumer Loans
Indirect		139
Home Equity		425
Direct		74
		638

Residential Real Estate Mortgages		2,863

	$	5,540

Total nonaccrual loans	$	40,525	$	39,676

The following tables set forth information with regard to past due and nonperforming loans by loan class as of June 30, 2013 and December 31, 2012:

Age Analysis of Past Due Financing Receivables

As of June 30, 2013

(in thousands)

					Greater Than								Recorded
	31-60 Days		61-90 Days		90 Days		Total						Total
	Past Due		Past Due		Past Due		Past Due						Loans and
	Accruing		Accruing		Accruing		Accruing		Non-Accrual		Current		Leases
ORIGINATED
Commercial Loans
Commercial	$	195	$	20	$	-	$	215	$	2,622	$	583,101	$	585,938
Commercial Real Estate		1,692		-		-		1,692		10,716		875,555		887,963
Agricultural		154		20		-		174		595		63,834		64,603
Agricultural Real Estate		349		-		-		349		968		30,894		32,211
Business Banking		2,176		590		-		2,766		5,658		328,763		337,187
		4,566		630		-		5,196		20,559		1,882,147		1,907,902

Consumer Loans
Indirect		10,749		2,259		832		13,840		1,301		1,033,903		1,049,044
Home Equity		6,475		1,198		704		8,377		6,583		525,429		540,389
Direct		611		210		45		866		128		60,593		61,587
		17,835		3,667		1,581		23,083		8,012		1,619,925		1,651,020
Residential Real Estate Mortgages		487		1,085		358		1,930		6,414		654,548		662,892
	$	22,888	$	5,382	$	1,939	$	30,209	$	34,985	$	4,156,620	$	4,221,814

ACQUIRED
Commercial Loans
Commercial	$	473	$	5	$	-	$	478	$	446	$	137,215	$	138,139
Commercial Real Estate		-		-		-		-		-		242,322		242,322
Agricultural		-		-		-		-		-		25		25
Business Banking		74		-		-		74		1,593		78,842		80,509
		547		5		-		552		2,039		458,404		460,995

Consumer Loans
Indirect		751		162		23		936		139		164,267		165,342
Home Equity		307		754		38		1,099		425		93,370		94,894
Direct		38		30		4		72		74		8,769		8,915
		1,096		946		65		2,107		638		266,406		269,151
Residential Real Estate Mortgages		2,292		230		-		2,522		2,863		333,365		338,750
	$	3,935	$	1,181	$	65	$	5,181	$	5,540	$	1,058,175	$	1,068,896
Total Loans	$	26,823	$	6,563	$	2,004	$	35,390	$	40,525	$	5,214,795	$	5,290,710

As of December 31, 2012

(in thousands)

					Greater Than
	31-60 Days		61-90 Days		90 Days		Total						Recorded
	Past Due		Past Due		Past Due		Past Due						Total
	Accruing		Accruing		Accruing		Accruing		Non-Accrual		Current		Loans
Commercial Loans
Commercial	$	-	$	-	$	-	$	-	$	4,985	$	556,496	$	561,481
Commercial Real Estate		126		-		-		126		7,977		966,692		974,795
Agricultural		22		-		-		22		699		63,037		63,758
Agricultural Real Estate		108		-		103		211		1,038		36,128		37,377
Business Banking		3,019		708		45		3,772		6,738		355,450		365,960
		3,275		708		148		4,131		21,437		1,977,803		2,003,371

Consumer Loans
Indirect		10,956		2,477		1,205		14,638		1,557		964,802		980,997
Home Equity		6,065		1,223		681		7,969		7,247		560,066		575,282
Direct		717		144		84		945		266		65,648		66,859
		17,738		3,844		1,970		23,552		9,070		1,590,516		1,623,138
Residential Real Estate Mortgages		1,839		725		330		2,894		9,169		639,044		651,107
	$	22,852	$	5,277	$	2,448	$	30,577	$	39,676	$	4,207,363	$	4,277,616

Impaired loans and specific reserve allocations

The following table provides information on impaired loans and specific reserve allocations as of June 30, 2013 and December 31, 2012:

	June 30, 2013						December 31, 2012
	Recorded		Unpaid				Recorded		Unpaid
	Investment		Principal				Investment		Principal
	Balance		Balance		Related		Balance		Balance		Related
(in thousands)	(Book)		(Legal)		Allowance		(Book)		(Legal)		Allowance
With no related allowance recorded:
Commercial Loans
Commercial	$	4,067	$	5,337			$	1,651	$	1,710
Commercial Real Estate		4,347		5,134				8,709		9,553
Agricultural		616		917				940		1,286
Agricultural Real Estate		1,634		1,955				1,713		2,026
Business Banking		7,534		10,213				7,048		9,579
Total Commercial Loans		18,198		23,556				20,061		24,154

Consumer Loans
Home Equity		2,971		3,156				2,553		2,657

Residential Real Estate Mortgages		2,018		2,360				2,011		2,308
	$	23,187	$	29,072			$	24,625	$	29,119

With an allowance recorded:
Commercial Loans
Commercial	$	-	$	-	$	-	$	4,335	$	4,340	$	2,241
Commercial Real Estate		7,302		8,924		2,032		4,068		5,689		607
Agricultural		-		-		-		-		-		-
Agricultural Real Estate		-		-		-		-		-		-
		7,302		8,924		2,032		8,403		10,029		2,848

Total:	$	30,489	$	37,996	$	2,032	$	33,028	$	39,148	$	2,848

The following tables summarize the average recorded investments on impaired loans and the interest income recognized for the three and six months ended June 30, 2013 and 2012:

	For the three months ended
	June 30, 2013				June 30, 2012
	Average		Interest		Average		Interest
	Recorded		Income		Recorded		Income
(in thousands)	Investment		Recognized		Investment		Recognized
Commercial Loans
Commercial	$	2,822	$	15	$	1,128	$	46
Commercial Real Estate		8,616		11		7,140		-
Agricultural		770		-		2,876		5
Agricultural Real Estate		1,123		12		1,876		53
Business Banking		7,843		16		6,572		8
Consumer Loans
Home Equity		2,907		6		1,828		2
Residential Real Estate Mortgages		1,990		15		1,055		-
Total:	$	26,071	$	75	$	22,475	$	114

	For the six months ended
	June 30, 2013				June 30, 2012
	Average		Interest		Average		Interest
	Recorded		Income		Recorded		Income
(in thousands)	Investment		Recognized		Investment		Recognized
Commercial Loans
Commercial	$	4,430	$	30	$	1,551	$	69
Commercial Real Estate		10,614		72		6,481		-
Agricultural		887		3		2,997		36
Agricultural Real Estate		1,482		24		1,926		53
Business Banking		8,016		30		7,151		12
Consumer Loans
Home Equity		2,775		12		1,869		3
Residential Real Estate Mortgages		1,989		27		1,043		-
Total:	$	30,193	$	198	$	23,018	$	173

Financing receivable credit quality by loan class

The following tables illustrate the Company’s credit quality by loan class as of June 30, 2013 and December 31, 2012:

Credit Quality Indicators

As of June 30, 2013

ORIGINATED
Commercial Credit Exposure			Commercial				Agricultural
By Internally Assigned Grade:	Commercial		Real Estate		Agricultural		Real Estate		Total
Pass	$	566,686	$	855,687	$	59,026	$	28,722	$	1,510,121
Special Mention		1,899		11,657		78		3		13,637
Substandard		16,850		19,856		5,476		3,486		45,668
Doubtful		503		763		23		-		1,289
Total	$	585,938	$	887,963	$	64,603	$	32,211	$	1,570,715

Business Banking Credit Exposure
By Internally Assigned Grade:	Small Business								Total
Non-classified	$	317,362							$	317,362
Classified		19,825								19,825
Total	$	337,187							$	337,187

Consumer Credit Exposure
By Payment Activity:	Indirect		Home Equity		Direct				Total
Performing	$	1,046,911	$	533,102	$	61,414			$	1,641,427
Nonperforming		2,133		7,287		173				9,593
Total	$	1,049,044	$	540,389	$	61,587			$	1,651,020

Residential Mortgage Credit Exposure	Residential
By Payment Activity:	Mortgage								Total
Performing	$	656,120							$	656,120
Nonperforming		6,772								6,772
Total	$	662,892							$	662,892

Credit Quality Indicators

As of June 30, 2013

ACQUIRED
Commercial Credit Exposure			Commercial
By Internally Assigned Grade:	Commercial		Real Estate		Agricultural		Total
Pass	$	121,901	$	220,131	$	25	$	342,057
Special Mention		8,323		8,822		-		17,145
Substandard		7,915		13,369		-		21,284
Doubtful		-		-		-		-
Total	$	138,139	$	242,322	$	25	$	380,486

Business Banking Credit Exposure
By Internally Assigned Grade:	Small Business						Total
Non-classified	$	75,418					$	75,418
Classified		5,091						5,091
Total	$	80,509					$	80,509

Consumer Credit Exposure
By Payment Activity:	Indirect		Home Equity		Direct		Total
Performing	$	165,180	$	94,006	$	8,763	$	267,949
Nonperforming		162		888		152		1,202
Total	$	165,342	$	94,894	$	8,915	$	269,151

Residential Mortgage Credit Exposure	Residential
By Payment Activity:	Mortgage						Total
Performing	$	335,887					$	335,887
Nonperforming		2,863						2,863
Total	$	338,750					$	338,750

Credit Quality Indicators

As of December 31, 2012

Commercial Credit Exposure			Commercial				Agricultural
By Internally Assigned Grade:	Commercial		Real Estate		Agricultural		Real Estate		Total
Pass	$	522,985	$	901,928	$	57,347	$	33,472	$	1,515,732
Special Mention		18,401		32,135		13		3		50,552
Substandard		17,351		40,732		6,362		3,902		68,347
Doubtful		2,744		-		36		-		2,780
Total	$	561,481	$	974,795	$	63,758	$	37,377	$	1,637,411

Business Banking. Credit Exposure
By Internally Assigned Grade:	Small Business								Total
Non-classified	$	342,528							$	342,528
Classified		23,432								23,432
Total	$	365,960							$	365,960

Consumer Credit Exposure
By Payment Activity:	Indirect		Home Equity		Direct				Total
Performing	$	978,235	$	567,354	$	66,509			$	1,612,098
Nonperforming		2,762		7,928		350				11,040
Total	$	980,997	$	575,282	$	66,859			$	1,623,138

Residential Mortgage Credit Exposure	Residential
By Payment Activity:	Mortgage								Total
Performing	$	641,608							$	641,608
Nonperforming		9,499								9,499
Total	$	651,107							$	651,107

Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2013

Earnings Per Share [Abstract]

Reconciliation of basic and diluted earnings per share

The following is a reconciliation of basic and diluted earnings per share for the periods presented in the consolidated statements of income.

Three months ended June 30,	2013		2012
(in thousands, except per share data)
Basic EPS:
Weighted average common shares outstanding		43,923		33,191
Net income available to common shareholders		16,916		13,257
Basic EPS	$	0.39	$	0.40
Diluted EPS:
Weighted average common shares outstanding		43,923		33,191
Dilutive effect of common stock options and restricted stock		393		301
Weighted average common shares and common share equivalents		44,316		33,492
Net income available to common shareholders		16,916		13,257
Diluted EPS	$	0.38	$	0.40

Six months ended June 30,		2013		2012
(in thousands, except per share data)
Basic EPS:
Weighted average common shares outstanding		40,187		33,128
Net income available to common shareholders		24,565		26,907
Basic EPS	$	0.61	$	0.81
Diluted EPS:
Weighted average common shares outstanding		40,187		33,128
Dilutive effect of common stock options and restricted stock		388		325
Weighted average common shares and common share equivalents		40,575		33,453
Net income available to common shareholders		24,565		26,907
Diluted EPS	$	0.61	$	0.80

Defined Benefit Postretirement Plans (Tables)

6 Months Ended

Jun. 30, 2013

Defined Benefit Postretirement Plans [Abstract]

Components of Net Periodic Pension Benefits and Other Benefit Costs

The components of expense for Pension Benefits and Other Benefits are set forth below (in thousands):

	Pension Benefits							Other Benefits
	Three months ended June 30,							Three months ended June 30,
Components of net periodic benefit cost:	2013				2012			2013				2012
Service cost		$	604		$	757			$	6		$	5
Interest cost			830			774				75			40
Expected return on plan assets			(1,929	)		(1,675	)			-			-
Net amortization			711			859				(1	)		(3	)
Total cost (benefit)		$	216		$	715			$	80		$	42

	Pension Benefits							Other Benefits
	Six months ended June 30,							Six months ended June 30,
Components of net periodic benefit cost:		2013			2012				2013			2012
Service cost		$	1,209		$	1,513			$	12		$	10
Interest cost			1,659			1,548				150			79
Expected return on plan assets			(3,858	)		(3,350	)			-			-
Net amortization			1,314			1,718				222			(5	)
Total cost (benefit)		$	324		$	1,429			$	384		$	84

Trust Preferred Debentures (Tables)

6 Months Ended

Jun. 30, 2013

Trust Preferred Debentures [Abstract]

Schedule of Debt of VIE Where Entity is Not Primary Beneficiary

As of June 30, 2013, the Trusts had the following issues of trust preferred debentures, all held by the Trusts, outstanding (dollars in thousands):

Description	Issuance Date	Trust Preferred Securities Outstanding		Interest Rate	Trust Preferred Debt Owed To Trust		Final Maturity Date

CNBF Capital Trust I	August-99	$	18,000	3-month LIBOR plus 2.75%	$	18,720	August-29

NBT Statutory Trust I	November-05		5,000	3-month LIBOR plus 1.40%		5,155	December-35

NBT Statutory Trust II	February-06		50,000	3-month LIBOR plus 1.40%		51,547	March-36

Alliance Financial Capital Trust I	December-03		10,000	3-month LIBOR plus 2.85%		10,310	January-34

Alliance Financial Capital Trust II	September-06		15,000	3-month LIBOR plus 1.65%		15,464	September-36

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21521-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 22
-Article 5

+ Details

Fair Values Measurements and Fair Value of Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2013

Fair Value Measurements and Fair Value of Financial Instruments [Abstract]

Fair Value of Financial Assets and Liabilities Measured on a Recurring Basis

June 30, 2013:

	Quoted Prices in		Significant Other		Significant
	Active Markets for		Observable		Unobservable		Balance
	Identical Assets		Inputs		Inputs		as of
	(Level 1)		(Level 2)		(Level 3)		June 30, 2013
Assets:
Securities Available for Sale:
U.S. Treasury	$	53,949	$	-	$	-	$	53,949
Federal Agency		-		279,458		-		279,458
State & municipal		-		126,674		-		126,674
Mortgage-backed		-		291,594		-		291,594
Collateralized mortgage obligations		-		622,768		-		622,768
Other securities		10,909		5,051		-		15,960
Total Securities Available for Sale	$	64,858	$	1,325,545	$	-	$	1,390,403
Trading Securities		5,092		-		-		5,092
Interest Rate Swaps		-		68		-		68
Total	$	69,950	$	1,325,613	$	-	$	1,395,563

Liabilities:
Interest Rate Swaps	$	-	$	68	$	-	$	68
Total	$	-	$	68	$	-	$	68

December 31, 2012:

	Quoted Prices in		Significant		Significant
	Active Markets for		Other		Unobservable		Balance
	Identical Assets		Observable Inputs		Inputs		as of
	(Level 1)		(Level 2)		(Level 3)		December 31, 2012
Assets:
Securities Available for Sale:
U.S. Treasury	$	64,425	$	-	$	-	$	64,425
Federal Agency		-		282,814		-		282,814
State & municipal		-		86,802		-		86,802
Mortgage-backed		-		250,281		-		250,281
Collateralized mortgage obligations		-		449,723		-		449,723
Other securities		11,866		2,088		-		13,954
Total Securities Available for Sale	$	76,291	$	1,071,708	$	-	$	1,147,999
Trading Securities		3,918		-		-		3,918
Interest Rate Swaps		-		1,490		-		1,490
Total	$	80,209	$	1,073,198	$	-	$	1,153,407

Liabilities:
Interest Rate Swaps	$	-	$	1,490	$	-	$	1,490
Total	$	-	$	1,490	$	-	$	1,490

Fair Value of Financial Instruments By Balance Sheet Grouping

			June 30, 2013				December 31, 2012
(In thousands)	Fair Value Hierarchy		Carrying amount		Estimated fair value		Carrying amount		Estimated fair value
Financial assets
Securities held to maturity		2	$	122,302	$	121,069	$	60,563	$	61,535
Net loans		3		5,219,526		5,287,651		4,208,282		4,313,244
Financial liabilities
Time deposits		2	$	1,105,038	$	1,112,212	$	983,261	$	994,376
Long-term debt		2		309,111		336,980		367,492		407,404
Trust preferred debentures		2		101,196		100,460		75,422		74,147

Securities (Tables)

6 Months Ended

Jun. 30, 2013

Securities [Abstract]

Amortized cost, estimated fair value, and unrealized gains and losses of securities available for sale

The amortized cost, estimated fair value, and unrealized gains and losses of securities available for sale are as follows:

(In thousands)	Amortized cost		Unrealized gains		Unrealized losses		Estimated fair value
June 30, 2013
U.S. Treasury	$	53,440	$	509	$	-	$	53,949
Federal Agency		286,049		192		6,783		279,458
State & municipal		125,792		2,375		1,493		126,674
Mortgage-backed:
Government-sponsored enterprises		260,130		6,149		1,487		264,792
U.S. government securities		25,608		1,269		75		26,802
Collateralized mortgage obligations:
Government-sponsored enterprises		573,487		2,677		6,747		569,417
U.S. government securities		52,421		970		40		53,351
Other securities		13,409		2,720		169		15,960
Total securities available for sale	$	1,390,336	$	16,861	$	16,794	$	1,390,403
December 31, 2012
U.S. Treasury	$	63,668	$	757	$	-	$	64,425
Federal Agency		281,398		1,507		91		282,814
State & municipal		82,675		4,127		-		86,802
Mortgage-backed:
Government-sponsored enterprises		221,110		11,175		-		232,285
U.S. government securities		16,351		1,645		-		17,996
Collateralized mortgage obligations:
Government-sponsored enterprises		399,147		4,418		-		403,565
U.S. government securities		44,825		1,333		-		46,158
Other securities		11,210		2,832		88		13,954
Total securities available for sale	$	1,120,384	$	27,794	$	179	$	1,147,999

Amortized cost, estimated fair value, and unrealized gains and losses of securities held to maturity

The amortized cost, estimated fair value, and unrealized gains and losses of securities held to maturity are as follows:

	Amortized		Unrealized		Unrealized		Estimated
(In thousands)	cost		gains		losses		fair value
June 30, 2013
Mortgage-backed	$	1,070	$	151	$	-	$	1,221
Collateralized mortgage oblications		64,022		-		1,964		62,058
State & municipal		57,210		580		-		57,790
Total securities held to maturity	$	122,302	$	731	$	1,964	$	121,069
December 31, 2012
Mortgage-backed	$	1,168	$	184	$	-	$	1,352
Collateralized mortgage oblications		-		-		-		0
State & municipal		59,395		788		-		60,183
Total securities held to maturity	$	60,563	$	972	$	-	$	61,535

Investment securities with unrealized losses

The following table sets forth information with regard to investment securities with unrealized losses at June 30, 2013 and December 31, 2012:

	Less than 12 months							12 months or longer							Total
Security Type:	Fair Value		Unrealized losses			Number of Positions		Fair Value		Unrealized losses			Number of Positions		Fair Value		Unrealized losses			Number of Positions

June 30, 2013
Investment securities available for sale:
U.S. Treasury	$	-	$	-			-	$	-	$	-			-	$	-	$	-			-
Federal agency		286,049		(6,783	)		20		-		-			-		286,049		(6,783	)		20
State & municipal		125,792		(1,493	)		193		-		-			-		125,792		(1,493	)		193
Mortgage-backed		285,687		(1,562	)		94		-		-			-		285,687		(1,562	)		94
Collateralized mortgage obligations		625,908		(6,787	)		28		-		-			-		625,908		(6,787	)		28
Other securities		5,560		(132	)		2		211		(37	)		1		5,771		(169	)		3
Total securities with unrealized losses	$	1,328,996	$	(16,757	)		337	$	211	$	(37	)		1	$	1,329,207	$	(16,794	)		338

June 30, 2013
Investment securities held to maturity:
Collateralized mortgage obligations		64,022		(1,964	)		5		-		-			-		64,022		(1,964	)		5
Total securities with unrealized losses	$	64,022	$	(1,964	)		5	$	-	$	-			-	$	64,022	$	(1,964	)		5

	Less than 12 months							12 months or longer							Total
	Fair Value		Unrealized losses			Number of Positions		Fair Value		Unrealized losses			Number of Positions		Fair Value		Unrealized losses			Number of Positions
December 31, 2012
Investment securities available for sale:
U.S. Treasury	$	-	$	-			-	$	-	$	-			-	$	-	$	-			-
Federal agency		39,906		(91	)		4		-		-			-		39,906		(91	)		4
State & municipal		-		-			-		-		-			-		-		-			-
Mortgage-backed		-		-			-		-		-			-		-		-			-
Collateralized mortgage obligations		23		-			2		-		-			-		23		-			2
Other securities		468		(6	)		1		167		(82	)		1		635		(88	)		2
Total securities with unrealized losses	$	40,397	$	(97	)		7	$	167	$	(82	)		1	$	40,564	$	(179	)		8

Contractual maturities of debt securities

The following tables set forth information with regard to contractual maturities of debt securities at June 30, 2013:

(In thousands)	Amortized cost		Estimated fair value
Debt securities classified as available for sale
Within one year	$	26,789	$	26,915
From one to five years		194,833		195,558
From five to ten years		348,099		345,525
After ten years		807,206		806,445
	$	1,376,927	$	1,374,443
Debt securities classified as held to maturity
Within one year	$	25,315	$	25,415
From one to five years		24,620		25,095
From five to ten years		5,651		5,656
After ten years		66,716		64,903
	$	122,302	$	121,069

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details

- Definition

Tabular disclosure of all investments in certain debt and equity securities for which the entity has the positive intent and ability to hold until maturity.

+ References + Details

Reclassification Adjustments Out of Other Comprehensive (Loss) Income (Tables)

6 Months Ended

Jun. 30, 2013

Reclassification Adjustments Out of Other Comprehensive Loss income [Abstract]

Reclassification out of Accumulated Other Comprehensive Income

The following table summarizes the reclassification adjustments out of accumulated other comprehensive loss (in thousands):

Detail About Accumulated Other Comprehensive (Loss) Income Components	Amount reclassified from accumulated other comprehensive income (loss)						Affected line item in the consolidated statement of comprehensive income
	Three months ended
	June 30, 2013			June 30, 2012
Available for sale securities:
Unrealized losses (gains) on available for sale securities	$	61		$	(97	)	Net securities gains
Tax (benefit) expense		(24	)		39		Income tax expense
Net of tax	$	37		$	(58	)

Pension and other benefits:
Amortization of net gains	$	765		$	911		Salaries and employee benefits
Amortization of prior service costs		(55	)		(55	)	Salaries and employee benefits
Tax benefit		284			345		Income tax expense
Net of tax	$	426		$	511

Total reclassifications during the period, net of tax	$	463		$	453

Detail About Accumulated Other Comprehensive (Loss) Income Components	Amount reclassified from accumulated other comprehensive income (loss)						Affected line item in the consolidated statement of comprehensive income
	Six months ended
	June 30, 2013			June 30, 2012
Available for sale securities:
Unrealized gains on available for sale securities	$	(1,084	)	$	(552	)	Net securities gains
Tax expense		434			221		Income tax expense
Net of tax	$	(650	)	$	(331	)

Pension and other benefits:
Amortization of net gains	$	1,647		$	1,824		Salaries and employee benefits
Amortization of prior service costs		(111	)		(111	)	Salaries and employee benefits
Tax benefit		614			686		Income tax expense
Net of tax	$	922		$	1,027

Total reclassifications during the period, net of tax	$	272		$	696

Acquisition (Details) $ in Thousands		3 Months Ended		6 Months Ended
Acquisition (Details) $ in Thousands	Mar. 08, 2013 USD ($) Branch shares	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)	Jun. 30, 2013 USD ($) shares	Jun. 30, 2012 USD ($)	Dec. 31, 2012 USD ($)
Business Acquisition [Line Items]
Direct costs related acquisition		$ 1,269	$ 826	$ 11,950	$ 1,337
Recognized Amounts of Identifiable Assets Acquired and (Liabilities Assumed), At Fair Value [Abstract]
Goodwill		264,376		264,376		$ 152,373
Information about acquired loan portfolio [Abstract]
Contractual cash flows not expected to be collected	$ (15,466)
Expected cash flows at acquisition	893,148
Interest component of expected cash flows (accretable premium)	11,325
Fair value of acquired loans	$ 904,473
Changes in accretable discount [Abstract]
Balance at January 1, 2013				0
Accretion recognized to date				(994)
Balance at June 30, 2013		$ 10,331		10,331
Net Income (Loss) [Abstract]
Net interest income				120,593	119,471
Noninterest income				55,445	52,738
Net income				$ 33,911	$ 32,104
Alliance Financial Corporation [Member]
Business Acquisition [Line Items]
Date of acquisition				Mar. 08, 2013
Number of banking centers operated by acquiree \| Branch	26
Business acquisition shares converted right to receive entity's common stock (in shares) \| shares	2.1779
Number of shares of common stock issued to acquiree shareholders (in shares) \| shares				10,300,000
Direct costs related acquisition				$ 11,950
Core deposit and trust intangible assets useful Live, Minimum				10 years
Core deposit and trust intangible assets useful Lives, Maximum				15 years
Consideration Paid [Abstract]
NBT Bancorp common stock issued	$ 225,551
Cash in lieu of fractional shares paid to Alliance common shareholders	11
Less treasury shares	5,779
Total consideration paid	219,783
Recognized Amounts of Identifiable Assets Acquired and (Liabilities Assumed), At Fair Value [Abstract]
Cash and short term investments	81,060
Securities	320,618
Loans	904,473
Core deposit intangibles	13,161
Other assets	71,823
Deposits	(1,113,420)
Borrowings	(126,530)
Trust Preferred debentures	(25,774)
Other liabilities	(18,466)
Total identifiable net assets	106,945
Goodwill	112,838
Information about acquired loan portfolio [Abstract]
Contractually required principal and interest at acquisition	$ 908,614
Changes in accretable discount [Abstract]
Alliance acquisition				$ 11,325
Hampshire First Bank [Member]
Other goodwill adjustments [Abstract]
Goodwill, Purchase Accounting Adjustments				(1,000)
Acquisition of Financial Services Company [Member]
Other goodwill adjustments [Abstract]
Goodwill, Purchase Accounting Adjustments				$ 100

Commitments and Contingencies (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Commitment to Extend Credits and Unused Lines of Credit [Member]
Guarantor Obligations [Line Items]
Commitments - maximum potential obligation	$ 1,100.0	$ 841.7
Standby Letters of Credit [Member]
Guarantor Obligations [Line Items]
Commitments - maximum potential obligation	$ 41,500.0	37.5
Obligation instrument term	5 years
Commercial Letters of Credit [Member]
Guarantor Obligations [Line Items]
Commitments - maximum potential obligation	$ 36,900.0	$ 16.6

Allowance for Loan Losses and Credit Quality of Loans, Allowance for Loan Losses (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)	Jun. 30, 2013 USD ($) Segment	Jun. 30, 2012 USD ($)	Jun. 30, 2013 USD ($)	Dec. 31, 2012 USD ($)
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance as of Beginning of Period	$ 68,734,000	$ 71,334,000	$ 69,334,000	$ 71,334,000
Charge-offs	(5,153,000)	(5,680,000)	(12,869,000)	(11,220,000)
Recoveries	1,201,000	977,000	2,659,000	2,046,000
Provision	6,402,000	4,103,000	12,060,000	8,574,000
Balance as of Ending of Period	71,184,000	70,734,000	71,184,000	70,734,000
Allowance for loan losses for acquired loan portfolio			0	0
Provision expense and net charge-offs related to acquired loans	200,000		400,000
Allowance loan losses [Abstract]
Allowance for loan losses	71,184,000	70,734,000	69,334,000	71,334,000	$ 71,184,000	$ 69,334,000
Allowance for loans and leases individually evaluated for impairment					2,032,000	2,848,000
Allowance for loans and leases collectively evaluated for impairment					69,152,000	66,486,000
Ending balance of loans and leases					5,290,710,000	4,277,616,000
Ending balance of loans and leases individually evaluated for impairment					12,887,000	11,972,000
Ending balance of acquired loans and leases					1,068,896,000
Ending balance of loans and leases collectively evaluated for impairment					4,208,927,000	4,265,644,000
Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance as of Beginning of Period	35,358,000	37,787,000	35,624,000	38,831,000
Charge-offs	(1,198,000)	(1,653,000)	(4,520,000)	(2,783,000)
Recoveries	416,000	303,000	883,000	688,000
Provision	3,128,000	1,058,000	5,717,000	759,000
Balance as of Ending of Period	37,704,000	37,495,000	37,704,000	37,495,000
Allowance loan losses [Abstract]
Allowance for loan losses	37,704,000	37,495,000	$ 35,624,000	38,831,000	37,704,000	35,624,000
Allowance for loans and leases individually evaluated for impairment					2,032,000	2,848,000
Allowance for loans and leases collectively evaluated for impairment					35,672,000	32,776,000
Ending balance of loans and leases					2,368,897,000	2,003,371,000
Ending balance of loans and leases individually evaluated for impairment					12,887,000	11,972,000
Ending balance of acquired loans and leases					460,995,000
Ending balance of loans and leases collectively evaluated for impairment					$ 1,895,015,000	1,991,399,000
Commercial Loans [Member] \| Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan portfolio segments \| Segment			3
Real estate loan amount, percentage of appraised value or purchase price of the property, maximum (in hundredths)					80.00%
Commercial Loans [Member] \| Agricultural Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Real estate loan amount, percentage of appraised value or purchase price of the property, maximum (in hundredths)					75.00%
Allowance loan losses [Abstract]
Ending balance of loans and leases						37,377,000
Commercial Loans [Member] \| Business Banking [Member]
Allowance loan losses [Abstract]
Ending balance of loans and leases						365,960,000
Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance as of Beginning of Period	26,285,000	26,790,000	$ 27,162,000	26,049,000
Charge-offs	(3,653,000)	(3,735,000)	(7,376,000)	(7,787,000)
Recoveries	696,000	667,000	1,673,000	1,342,000
Provision	3,128,000	3,513,000	4,997,000	7,631,000
Balance as of Ending of Period	26,456,000	27,235,000	26,456,000	27,235,000
Allowance loan losses [Abstract]
Allowance for loan losses	26,456,000	27,235,000	$ 27,162,000	26,049,000	$ 26,456,000	27,162,000
Allowance for loans and leases individually evaluated for impairment					0	0
Allowance for loans and leases collectively evaluated for impairment					26,456,000	27,162,000
Ending balance of loans and leases					1,920,171,000	1,623,138,000
Ending balance of loans and leases individually evaluated for impairment					0	0
Ending balance of acquired loans and leases					269,151,000
Ending balance of loans and leases collectively evaluated for impairment					1,651,020,000	1,623,138,000
Consumer Loans [Member] \| Business Banking [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Business banking loans, maximum amount					$ 500,000
Consumer Loans [Member] \| Indirect [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of automobile financing to indirect relationships with dealers (in hundredths)					75.00%
Principal repayment term of loan, minimum (in years)			3 years
Principal repayment term of loan, maximum (in years)			6 years
Allowance loan losses [Abstract]
Ending balance of loans and leases						980,997,000
Consumer Loans [Member] \| Home Equity [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Home equity loan amount, percentage of equity in home, maximum (in hundredths)			85.00%
Consumer Loans [Member] \| Direct [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal repayment term of loan, minimum (in years)			1 year
Principal repayment term of loan, maximum (in years)			10 years
Allowance loan losses [Abstract]
Ending balance of loans and leases						66,859,000
Residential Real Estate Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Real estate loan amount, percentage of appraised value or purchase price of the property, maximum (in hundredths)					85.00%
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance as of Beginning of Period	6,708,000	6,520,000	$ 6,252,000	6,249,000
Charge-offs	(302,000)	(292,000)	(973,000)	(650,000)
Recoveries	89,000	7,000	103,000	16,000
Provision	311,000	(292,000)	1,424,000	328,000
Balance as of Ending of Period	6,806,000	5,943,000	6,806,000	5,943,000
Allowance loan losses [Abstract]
Allowance for loan losses	6,806,000	5,943,000	6,806,000	6,249,000	$ 6,806,000	6,252,000
Allowance for loans and leases individually evaluated for impairment					0	0
Allowance for loans and leases collectively evaluated for impairment					6,806,000	6,252,000
Ending balance of loans and leases					1,001,642,000	651,107,000
Ending balance of loans and leases individually evaluated for impairment					0	0
Ending balance of acquired loans and leases					338,750,000
Ending balance of loans and leases collectively evaluated for impairment					662,892,000	651,107,000
Unallocated [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance as of Beginning of Period	383,000	237,000	296,000	205,000
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Provision	(165,000)	(176,000)	(78,000)	(144,000)
Balance as of Ending of Period	218,000	61,000	218,000	61,000
Allowance loan losses [Abstract]
Allowance for loan losses	$ 218,000	$ 61,000	$ 218,000	$ 205,000	218,000	296,000
Allowance for loans and leases collectively evaluated for impairment					$ 218,000	$ 296,000

Allowance for Loan Losses and Credit Quality of Loans, Past Due Loans (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment, Aging [Abstract]
Minimum number of days past due for nonaccrual loan status	90 days
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	$ 26,823	$ 22,852
61 - 90 Days Past Due Accruing	6,563	5,277
Greater Than 90 Days Past Due Accruing	2,004	2,448
Total Past Due Accruing	35,390	30,577
Non-Accrual	40,525	39,676
Current	5,214,795	4,207,363
Ending balance of loans	5,290,710	4,277,616
Originated loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	22,888
61 - 90 Days Past Due Accruing	5,382
Greater Than 90 Days Past Due Accruing	1,939
Total Past Due Accruing	30,209
Non-Accrual	34,985	39,676
Current	4,156,620
Ending balance of loans	4,221,814
ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	3,935
61 - 90 Days Past Due Accruing	1,181
Greater Than 90 Days Past Due Accruing	65
Total Past Due Accruing	5,181
Non-Accrual	5,540
Current	1,058,175
Ending balance of loans	1,068,896
Commercial Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
Ending balance of loans	2,368,897	2,003,371
Commercial Loans [Member] \| Originated loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
Non-Accrual	20,559	21,437
Commercial Loans [Member] \| ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
Non-Accrual	2,039
Commercial Loans [Member] \| Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		0
61 - 90 Days Past Due Accruing		0
Greater Than 90 Days Past Due Accruing		0
Total Past Due Accruing		0
Non-Accrual		4,985
Current		556,496
Ending balance of loans		561,481
Commercial Loans [Member] \| Commercial [Member] \| Originated loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	195
61 - 90 Days Past Due Accruing	20
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	215
Non-Accrual	2,622	4,985
Current	583,101
Ending balance of loans	585,938
Commercial Loans [Member] \| Commercial [Member] \| ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	473
61 - 90 Days Past Due Accruing	5
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	478
Non-Accrual	446
Current	137,215
Ending balance of loans	138,139
Commercial Loans [Member] \| Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		126
61 - 90 Days Past Due Accruing		0
Greater Than 90 Days Past Due Accruing		0
Total Past Due Accruing		126
Non-Accrual		7,977
Current		966,692
Ending balance of loans		974,795
Commercial Loans [Member] \| Commercial Real Estate [Member] \| Originated loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	1,692
61 - 90 Days Past Due Accruing	0
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	1,692
Non-Accrual	10,716	7,977
Current	875,555
Ending balance of loans	887,963
Commercial Loans [Member] \| Commercial Real Estate [Member] \| ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	0
61 - 90 Days Past Due Accruing	0
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	0
Non-Accrual	0
Current	242,322
Ending balance of loans	242,322
Commercial Loans [Member] \| Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		22
61 - 90 Days Past Due Accruing		0
Greater Than 90 Days Past Due Accruing		0
Total Past Due Accruing		22
Non-Accrual		699
Current		63,037
Ending balance of loans		63,758
Commercial Loans [Member] \| Agricultural [Member] \| Originated loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	154
61 - 90 Days Past Due Accruing	20
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	174
Non-Accrual	595	699
Current	63,834
Ending balance of loans	64,603
Commercial Loans [Member] \| Agricultural [Member] \| ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	0
61 - 90 Days Past Due Accruing	0
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	0
Non-Accrual	0
Current	25
Ending balance of loans	25
Commercial Loans [Member] \| Agricultural Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		108
61 - 90 Days Past Due Accruing		0
Greater Than 90 Days Past Due Accruing		103
Total Past Due Accruing		211
Non-Accrual		1,038
Current		36,128
Ending balance of loans		37,377
Commercial Loans [Member] \| Agricultural Real Estate [Member] \| Originated loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	349
61 - 90 Days Past Due Accruing	0
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	349
Non-Accrual	968	1,038
Current	30,894
Ending balance of loans	32,211
Commercial Loans [Member] \| Business Banking [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		3,019
61 - 90 Days Past Due Accruing		708
Greater Than 90 Days Past Due Accruing		45
Total Past Due Accruing		3,772
Non-Accrual		6,738
Current		355,450
Ending balance of loans		365,960
Commercial Loans [Member] \| Business Banking [Member] \| Originated loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	2,176
61 - 90 Days Past Due Accruing	590
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	2,766
Non-Accrual	5,658	6,738
Current	328,763
Ending balance of loans	337,187
Commercial Loans [Member] \| Business Banking [Member] \| ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	74
61 - 90 Days Past Due Accruing	0
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	74
Non-Accrual	1,593
Current	78,842
Ending balance of loans	80,509
Commercial Loans [Member] \| Total Commercial Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		3,275
61 - 90 Days Past Due Accruing		708
Greater Than 90 Days Past Due Accruing		148
Total Past Due Accruing		4,131
Non-Accrual		21,437
Current		1,977,803
Ending balance of loans		2,003,371
Commercial Loans [Member] \| Total Commercial Loan [Member] \| Originated loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	4,566
61 - 90 Days Past Due Accruing	630
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	5,196
Non-Accrual	20,559
Current	1,882,147
Ending balance of loans	1,907,902
Commercial Loans [Member] \| Total Commercial Loan [Member] \| ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	547
61 - 90 Days Past Due Accruing	5
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	552
Non-Accrual	2,039
Current	458,404
Ending balance of loans	460,995
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
Ending balance of loans	1,920,171	1,623,138
Consumer Loans [Member] \| Originated loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
Non-Accrual	8,012	9,070
Consumer Loans [Member] \| ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
Non-Accrual	638
Consumer Loans [Member] \| Indirect [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		10,956
61 - 90 Days Past Due Accruing		2,477
Greater Than 90 Days Past Due Accruing		1,205
Total Past Due Accruing		14,638
Non-Accrual		1,557
Current		964,802
Ending balance of loans		980,997
Consumer Loans [Member] \| Indirect [Member] \| Originated loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	10,749
61 - 90 Days Past Due Accruing	2,259
Greater Than 90 Days Past Due Accruing	832
Total Past Due Accruing	13,840
Non-Accrual	1,301	1,557
Current	1,033,903
Ending balance of loans	1,049,044
Consumer Loans [Member] \| Indirect [Member] \| ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	751
61 - 90 Days Past Due Accruing	162
Greater Than 90 Days Past Due Accruing	23
Total Past Due Accruing	936
Non-Accrual	139
Current	164,267
Ending balance of loans	165,342
Consumer Loans [Member] \| Home Equity Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		6,065
61 - 90 Days Past Due Accruing		1,223
Greater Than 90 Days Past Due Accruing		681
Total Past Due Accruing		7,969
Non-Accrual		7,247
Current		560,066
Ending balance of loans		575,282
Consumer Loans [Member] \| Home Equity Member] \| Originated loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	6,475
61 - 90 Days Past Due Accruing	1,198
Greater Than 90 Days Past Due Accruing	704
Total Past Due Accruing	8,377
Non-Accrual	6,583	7,247
Current	525,429
Ending balance of loans	540,389
Consumer Loans [Member] \| Home Equity Member] \| ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	307
61 - 90 Days Past Due Accruing	754
Greater Than 90 Days Past Due Accruing	38
Total Past Due Accruing	1,099
Non-Accrual	425
Current	93,370
Ending balance of loans	94,894
Consumer Loans [Member] \| Direct [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		717
61 - 90 Days Past Due Accruing		144
Greater Than 90 Days Past Due Accruing		84
Total Past Due Accruing		945
Non-Accrual		266
Current		65,648
Ending balance of loans		66,859
Consumer Loans [Member] \| Direct [Member] \| Originated loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	611
61 - 90 Days Past Due Accruing	210
Greater Than 90 Days Past Due Accruing	45
Total Past Due Accruing	866
Non-Accrual	128	266
Current	60,593
Ending balance of loans	61,587
Consumer Loans [Member] \| Direct [Member] \| ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	38
61 - 90 Days Past Due Accruing	30
Greater Than 90 Days Past Due Accruing	4
Total Past Due Accruing	72
Non-Accrual	74
Current	8,769
Ending balance of loans	8,915
Consumer Loans [Member] \| Total Consumer Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		17,738
61 - 90 Days Past Due Accruing		3,844
Greater Than 90 Days Past Due Accruing		1,970
Total Past Due Accruing		23,552
Non-Accrual		9,070
Current		1,590,516
Ending balance of loans		1,623,138
Consumer Loans [Member] \| Total Consumer Loan [Member] \| Originated loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	17,835
61 - 90 Days Past Due Accruing	3,667
Greater Than 90 Days Past Due Accruing	1,581
Total Past Due Accruing	23,083
Non-Accrual	8,012
Current	1,619,925
Ending balance of loans	1,651,020
Consumer Loans [Member] \| Total Consumer Loan [Member] \| ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	1,096
61 - 90 Days Past Due Accruing	946
Greater Than 90 Days Past Due Accruing	65
Total Past Due Accruing	2,107
Non-Accrual	638
Current	266,406
Ending balance of loans	269,151
Residential Real Estate Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing		1,839
61 - 90 Days Past Due Accruing		725
Greater Than 90 Days Past Due Accruing		330
Total Past Due Accruing		2,894
Non-Accrual		9,169
Current		639,044
Ending balance of loans	1,001,642	651,107
Residential Real Estate Mortgages [Member] \| Originated loans [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	487
61 - 90 Days Past Due Accruing	1,085
Greater Than 90 Days Past Due Accruing	358
Total Past Due Accruing	1,930
Non-Accrual	6,414	$ 9,169
Current	654,548
Ending balance of loans	662,892
Residential Real Estate Mortgages [Member] \| ACQUIRED [Member]
Financing Receivable, Recorded Investment, Past Due [Abstract]
31 - 60 Days Past Due Accruing	2,292
61 - 90 Days Past Due Accruing	230
Greater Than 90 Days Past Due Accruing	0
Total Past Due Accruing	2,522
Non-Accrual	2,863
Current	333,365
Ending balance of loans	$ 338,750

Allowance for Loan Losses and Credit Quality of Loans, Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Allowance for Loan Losses and Credit Quality of Loans [Abstract]
Minimum balance for classified loans to be evaluated individually for impairment	$ 500		$ 500
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	26,071	$ 22,475	30,193	$ 23,018
Interest Income Recognized	75	114	198	173
Commercial Loans [Member] \| Commercial [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	2,822	1,128	4,430	1,551
Interest Income Recognized	15	46	30	69
Commercial Loans [Member] \| Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	8,616	7,140	10,614	6,481
Interest Income Recognized	11	0	72	0
Commercial Loans [Member] \| Agricultural [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	770	2,876	887	2,997
Interest Income Recognized	0	5	3	36
Commercial Loans [Member] \| Agricultural Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,123	1,876	1,482	1,926
Interest Income Recognized	12	53	24	53
Commercial Loans [Member] \| Business Banking [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	7,843	6,572	8,016	7,151
Interest Income Recognized	16	8	30	12
Consumer Loans [Member] \| Home Equity [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	2,907	1,828	2,775	1,869
Interest Income Recognized	6	2	12	3
Residential Real Estate Mortgages [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,990	1,055	1,989	1,043
Interest Income Recognized	15	$ 0	27	$ 0
With No Allowance Recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment Balance (Book)	23,187		23,187		$ 24,625
Unpaid Principal Balance (Legal)	29,072		29,072		29,119
With No Allowance Recorded [Member] \| Commercial Loans [Member] \| Commercial [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment Balance (Book)	4,067		4,067		1,651
Unpaid Principal Balance (Legal)	5,337		5,337		1,710
With No Allowance Recorded [Member] \| Commercial Loans [Member] \| Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment Balance (Book)	4,347		4,347		8,709
Unpaid Principal Balance (Legal)	5,134		5,134		9,553
With No Allowance Recorded [Member] \| Commercial Loans [Member] \| Agricultural [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment Balance (Book)	616		616		940
Unpaid Principal Balance (Legal)	917		917		1,286
With No Allowance Recorded [Member] \| Commercial Loans [Member] \| Agricultural Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment Balance (Book)	1,634		1,634		1,713
Unpaid Principal Balance (Legal)	1,955		1,955		2,026
With No Allowance Recorded [Member] \| Commercial Loans [Member] \| Business Banking [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment Balance (Book)	7,534		7,534		7,048
Unpaid Principal Balance (Legal)	10,213		10,213		9,579
With No Allowance Recorded [Member] \| Commercial Loans [Member] \| Total Commercial Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment Balance (Book)	18,198		18,198		20,061
Unpaid Principal Balance (Legal)	23,556		23,556		24,154
With No Allowance Recorded [Member] \| Consumer Loans [Member] \| Home Equity [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment Balance (Book)	2,971		2,971		2,553
Unpaid Principal Balance (Legal)	3,156		3,156		2,657
With No Allowance Recorded [Member] \| Residential Real Estate Mortgages [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment Balance (Book)	2,018		2,018		2,011
Unpaid Principal Balance (Legal)	2,360		2,360		2,308
With An Allowance Recorded [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment Balance (Book)	30,489		30,489		33,028
Unpaid Principal Balance (Legal)	37,996		37,996		39,148
Related Allowance	2,032		2,032		2,848
With An Allowance Recorded [Member] \| Commercial Loans [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment Balance (Book)	7,302		7,302		8,403
Unpaid Principal Balance (Legal)	8,924		8,924		10,029
Related Allowance	2,032		2,032		2,848
With An Allowance Recorded [Member] \| Commercial Loans [Member] \| Commercial [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment Balance (Book)	0		0		4,335
Unpaid Principal Balance (Legal)	0		0		4,340
Related Allowance	0		0		2,241
With An Allowance Recorded [Member] \| Commercial Loans [Member] \| Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment Balance (Book)	7,302		7,302		4,068
Unpaid Principal Balance (Legal)	8,924		8,924		5,689
Related Allowance	2,032		2,032		607
With An Allowance Recorded [Member] \| Commercial Loans [Member] \| Agricultural [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment Balance (Book)	0		0		0
Unpaid Principal Balance (Legal)	0		0		0
Related Allowance	0		0		0
With An Allowance Recorded [Member] \| Commercial Loans [Member] \| Agricultural Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Recorded Investment Balance (Book)	0		0		0
Unpaid Principal Balance (Legal)	0		0		0
Related Allowance	$ 0		$ 0		$ 0

Allowance for Loan Losses and Credit Quality of Loans, Troubled Debt Restructurings (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)	Jun. 30, 2013 USD ($)	Jun. 30, 2012 USD ($)
Financing Receivable, Modifications [Line Items]
Period of sustained repayment performance for nonperforming TDRs to be returned to performing status (in months)			6 months
Residential Real Estate Mortgages [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts			1	1
Pre-modification outstanding recorded investment			$ 100,000	$ 200,000
Commercial Real Estate [Member] \| Residential Real Estate Mortgages [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1
Pre-modification outstanding recorded investment	$ 900,000
Commercial Real Estate [Member] \| Residential Real Estate Mortgages [Member] \| Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts			1
Pre-modification outstanding recorded investment			$ 900,000
Home Equity [Member] \| Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	10		14
Pre-modification outstanding recorded investment	$ 500,000		$ 600,000
Home Equity [Member] \| Subsequent Default [Member] \| Home Equity [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	3	1	3	1
Pre-modification outstanding recorded investment	$ 200,000	$ 25,000	$ 200,000	$ 25,000
Commercial Loans [Member] \| Commercial Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts		1		1
Pre-modification outstanding recorded investment		$ 1,000,000		$ 1,000,000
Residential Real Estate Mortgages [Member] \| Residential Real Estate Mortgages [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1
Pre-modification outstanding recorded investment	$ 100,000
Residential Real Estate Mortgages [Member] \| Subsequent Default [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts		3
Pre-modification outstanding recorded investment		$ 400,000

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Basic EPS [Abstract]
Weighted average common shares, Basic (in shares)	43,923,000	33,191,000	40,187,000	33,128,000
Net income available to common shareholders	$ 16,916	$ 13,257	$ 24,565	$ 26,907
Basic EPS (in dollars per share)	$ 0.39	$ 0.40	$ 0.61	$ 0.81
Diluted EPS [Abstract]
Weighted average common shares, Diluted (in shares)	43,923,000	33,191,000	40,187,000	33,128,000
Dilutive effect of common stock option and restricted stock (in shares)	393,000	301,000	388,000	325,000
Weighted average common shares and common share equivalent (in shares)	44,316,000	33,492,000	40,575,000	33,453,000
Net income available to common shareholders	$ 16,916	$ 13,257	$ 24,565	$ 26,907
Diluted EPS (in dollars per share)	$ 0.38	$ 0.40	$ 0.61	$ 0.80
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options excluded from calculation of diluted EPS (in shares)	1,231,395	1,271,116	1,203,046	1,209,201

Defined Benefit Postretirement Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Defined Benefit Plan Disclosure [Line Items]
Transition obligation amortization period			20 years
Pension Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	$ 604	$ 757	$ 1,209	$ 1,513
Interest cost	830	774	1,659	1,548
Expected return on plan assets	(1,929)	(1,675)	(3,858)	(3,350)
Net amortization	711	859	1,314	1,718
Total cost (benefit)	216	715	324	1,429
Other Benefits [Member]
Components of net periodic benefit cost [Abstract]
Service cost	6	5	12	10
Interest cost	75	40	150	79
Expected return on plan assets	0	0	0	0
Net amortization	(1)	(3)	222	(5)
Total cost (benefit)	$ 80	$ 42	$ 384	$ 84

Trust Preferred Debentures (Details) $ in Thousands	6 Months Ended
Trust Preferred Debentures (Details) $ in Thousands	Jun. 30, 2013 USD ($) Trust
Limited Guarantee Trust Preferred Debentures [Abstract]
Number of statutory business trusts included in the Trusts \| Trust	5
CNBF Capital Trust I VIE Entity Not Primary Beneficiary [Member] \| CNBF Capital Trust I Debenture [Member]
Limited Guarantee Trust Preferred Debentures [Abstract]
Issuance Date	Aug. 01, 1999
Trust Preferred Securities Outstanding	$ 18,000
Interest Rate	3-month LIBOR plus 2.75%
Trust Preferred Debt Owed To Trust	$ 18,720
Final Maturity Date	Aug. 01, 2029
NBT Statutory Trust I VIE Entity Not Primary Beneficiary [Member] \| NBT Statutory Trust I Debenture [Member]
Limited Guarantee Trust Preferred Debentures [Abstract]
Issuance Date	Nov. 01, 2005
Trust Preferred Securities Outstanding	$ 5,000
Interest Rate	3-month LIBOR plus 1.40%
Trust Preferred Debt Owed To Trust	$ 5,155
Final Maturity Date	Dec. 01, 2035
NBT Statutory Trust II VIE Entity Not Primary Beneficiary [Member] \| NBT Statutory Trust II Debenture [Member]
Limited Guarantee Trust Preferred Debentures [Abstract]
Issuance Date	Feb. 01, 2006
Trust Preferred Securities Outstanding	$ 50,000
Interest Rate	3-month LIBOR plus 1.40%
Trust Preferred Debt Owed To Trust	$ 51,547
Final Maturity Date	Mar. 01, 2036
Alliance Financial Capital Trust I VIE Entity Not Primary Beneficiary [Member] \| Alliance Financial Capital Trust I [Member]
Limited Guarantee Trust Preferred Debentures [Abstract]
Issuance Date	Dec. 01, 2003
Trust Preferred Securities Outstanding	$ 10,000
Interest Rate	3-month LIBOR plus 2.85%
Trust Preferred Debt Owed To Trust	$ 10,310
Final Maturity Date	Jan. 01, 2034
Alliance Financial Capital Trust II VIE Entity Not Primary Beneficiary [Member] \| Alliance Financial Capital Trust II [Member]
Limited Guarantee Trust Preferred Debentures [Abstract]
Issuance Date	Sep. 01, 2006
Trust Preferred Securities Outstanding	$ 15,000
Interest Rate	3-month LIBOR plus 1.65%
Trust Preferred Debt Owed To Trust	$ 15,464
Final Maturity Date	Sep. 01, 2036

Fair Values Measurements and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2013	Dec. 31, 2012
Securities Available for Sale [Abstract]
Total Securities Available for Sale	$ 1,390,403	$ 1,147,999
Trading Securities	5,092	3,918
Liabilities [Abstract]
Collateral dependent impaired financing receivable with specific reserves	7,300	8,400
Allowance for loan and lease losses collateral dependent impaired loans with specific reserves	$ 2,000	2,800
Liquidation expense ratio on impaired collateral minimum (in hundredths)	10.00%
Liquidation expense ratio on impaired collateral maximum (in hundredths)	35.00%
Financial assets [Abstract]
Securities held to maturity	$ 121,069	61,535
Financial liabilities [Abstract]
Time deposits	1,105,038	983,261
Long-term debt	309,111	367,492
Trust preferred debentures	101,196	75,422
Carrying Amount [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial assets [Abstract]
Securities held to maturity	122,302	60,563
Financial liabilities [Abstract]
Time deposits	1,105,038	983,261
Long-term debt	309,111	367,492
Trust preferred debentures	101,196	75,422
Carrying Amount [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial assets [Abstract]
Net Loans	5,219,526	4,208,282
Estimated Fair Value [Member] \| Fair Value, Inputs, Level 2 [Member]
Financial assets [Abstract]
Securities held to maturity	121,069	61,535
Financial liabilities [Abstract]
Time deposits	1,112,212	994,376
Long-term debt	336,980	407,404
Trust preferred debentures	100,460	74,147
Estimated Fair Value [Member] \| Fair Value, Inputs, Level 3 [Member]
Financial assets [Abstract]
Net Loans	5,287,651	4,313,244
Fair Value, Measurements, Recurring [Member]
Securities Available for Sale [Abstract]
U.S. Treasury	53,949	64,425
Federal Agency	279,458	282,814
State & municipal	126,674	86,802
Mortgage-backed	291,594	250,281
Collateralized mortgage obligations	622,768	449,723
Other securities	15,960	13,954
Total Securities Available for Sale	1,390,403	1,147,999
Trading Securities	5,092	3,918
Interest Rate Swaps	68	1,490
Total	1,395,563	1,153,407
Liabilities [Abstract]
Interest Rate Swaps	68	1,490
Total	68	1,490
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Securities Available for Sale [Abstract]
U.S. Treasury	53,949	64,425
Federal Agency	0	0
State & municipal	0	0
Mortgage-backed	0	0
Collateralized mortgage obligations	0	0
Other securities	10,909	11,866
Total Securities Available for Sale	64,858	76,291
Trading Securities	5,092	3,918
Interest Rate Swaps	0	0
Total	69,950	80,209
Liabilities [Abstract]
Interest Rate Swaps	0	0
Total	0	0
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Securities Available for Sale [Abstract]
U.S. Treasury	0	0
Federal Agency	279,458	282,814
State & municipal	126,674	86,802
Mortgage-backed	291,594	250,281
Collateralized mortgage obligations	622,768	449,723
Other securities	5,051	2,088
Total Securities Available for Sale	1,325,545	1,071,708
Trading Securities	0	0
Interest Rate Swaps	68	1,490
Total	1,325,613	1,073,198
Liabilities [Abstract]
Interest Rate Swaps	68	1,490
Total	68	1,490
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Securities Available for Sale [Abstract]
U.S. Treasury	0	0
Federal Agency	0	0
State & municipal	0	0
Mortgage-backed	0	0
Collateralized mortgage obligations	0	0
Other securities	0	0
Total Securities Available for Sale	0	0
Trading Securities	0	0
Interest Rate Swaps	0	0
Total	0	0
Liabilities [Abstract]
Interest Rate Swaps	0	0
Total	$ 0	$ 0

Securities (Details) $ in Thousands	3 Months Ended	6 Months Ended		12 Months Ended
Securities (Details) $ in Thousands	Jun. 30, 2013 USD ($) Position	Jun. 30, 2013 USD ($) Position	Jun. 30, 2012 USD ($)	Dec. 31, 2012 USD ($) Position
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 1,390,336	$ 1,390,336		$ 1,120,384
Unrealized gains		16,861		27,794
Unrealized losses		16,794		179
Estimated fair value	1,390,403	1,390,403		1,147,999
Sales transactions of securities available for sale [Abstract]
Proceeds from sales		26,200	$ 1,800
Gross realized gains		1,100	$ 600
Amortized costs of securities available for sale pledged to secure public deposits	1,500,000	1,500,000		1,200,000
Amortized costs of securities available for sale pledged as collateral for repurchase agreements	224,600	224,600		209,000
Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months, Fair Value	1,328,996	1,328,996		40,397
12 Months or Longer, Fair Value	211	211		167
Total, Fair Value	$ 1,329,207	1,329,207		40,564
Unrealized Loss Position, Unrealized Losses [Abstract]
Less Than 12 Months, Unrealized Losses		(16,757)		(97)
12 Months or Longer, Unrealized Losses		(37)		(82)
Total, Unrealized Losses		$ (16,794)		$ (179)
Unrealized Loss Position, Number of Positions [Abstract]
Less Than 12 Months, Number of Positions \| Position	337	337		7
12 Months or Longer, Number of Positions \| Position	1	1		1
Total, Number of Positions \| Position	338	338		8
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	$ 122,302	$ 122,302		$ 60,563
Unrealized gains	731			972
Unrealized losses	1,964			0
Total, Fair Value	121,069	121,069		61,535
Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months, Fair Value	64,022	64,022
12 Months or Longer, Fair Value	0	0
Total, Fair Value	$ 64,022	64,022
Unrealized Loss Position, Unrealized Losses [Abstract]
Less Than 12 Months, Unrealized Losses		(1,964)
12 Months or Longer, Unrealized Losses		0
Total, Unrealized Losses		$ (1,964)
Unrealized Loss Position, Number of Positions [Abstract]
Less Than 12 Months, Number of Positions \| Position	5	5
12 Months or Longer, Number of Positions \| Position	0	0
Total, Number of Positions \| Position	5	5
Consolidated stockholders' equity threshold percentage that no single issuer of securities exceeded except for U.S. Government securities. (in hundredths)	10.00%	10.00%
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis [Abstract]
Within one year	$ 26,789	$ 26,789
From one to five years	194,833	194,833
From five to ten years	348,099	348,099
After ten years	807,206	807,206
Total, Amortized Cost	1,376,927	1,376,927
Available-for-sale Securities, Debt Maturities, Fair Value [Abstract]
Within one year	26,915	26,915
From one to five years	195,558	195,558
From five to ten years	345,525	345,525
After ten years	806,445	806,445
Total, Fair Value	1,374,443	1,374,443
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Within one year	25,315	25,315
From one to five years	24,620	24,620
From five to ten years	5,651	5,651
After ten years	66,716	66,716
Securities held to maturity	122,302	122,302		60,563
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Within one year	25,415	25,415
From one to five years	25,095	25,095
From five to ten years	5,656	5,656
After ten years	64,903	64,903
Total, Fair Value	121,069	121,069		61,535
State & Municipal [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	57,210	57,210		59,395
Unrealized gains	580			788
Unrealized losses	0			0
Total, Fair Value	57,790	57,790		60,183
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Securities held to maturity	57,210	57,210		59,395
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value	57,790	57,790		60,183
Mortgage backed [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	1,070	1,070		1,168
Unrealized gains	151			184
Unrealized losses	0			0
Total, Fair Value	1,221	1,221		1,352
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Securities held to maturity	1,070	1,070		1,168
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value	1,221	1,221		1,352
U.S. government securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost				16,351
Unrealized gains				1,645
Unrealized losses				0
Estimated fair value				17,996
US Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	53,440	53,440		63,668
Unrealized gains		509		757
Unrealized losses		0		0
Estimated fair value	53,949	53,949		64,425
Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months, Fair Value	0	0		0
12 Months or Longer, Fair Value	0	0		0
Total, Fair Value	$ 0	0		0
Unrealized Loss Position, Unrealized Losses [Abstract]
Less Than 12 Months, Unrealized Losses		0		0
12 Months or Longer, Unrealized Losses		0		0
Total, Unrealized Losses		$ 0		$ 0
Unrealized Loss Position, Number of Positions [Abstract]
Less Than 12 Months, Number of Positions \| Position	0	0		0
12 Months or Longer, Number of Positions \| Position	0	0		0
Total, Number of Positions \| Position	0	0		0
Federal Agency [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 286,049	$ 286,049		$ 281,398
Unrealized gains		192		1,507
Unrealized losses		6,783		91
Estimated fair value	279,458	279,458		282,814
Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months, Fair Value	286,049	286,049		39,906
12 Months or Longer, Fair Value	0	0		0
Total, Fair Value	$ 286,049	286,049		39,906
Unrealized Loss Position, Unrealized Losses [Abstract]
Less Than 12 Months, Unrealized Losses		(6,783)		(91)
12 Months or Longer, Unrealized Losses		0		0
Total, Unrealized Losses		$ (6,783)		$ (91)
Unrealized Loss Position, Number of Positions [Abstract]
Less Than 12 Months, Number of Positions \| Position	20	20		4
12 Months or Longer, Number of Positions \| Position	0	0		0
Total, Number of Positions \| Position	20	20		4
Mortgage backed [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months, Fair Value	$ 285,687	$ 285,687		$ 0
12 Months or Longer, Fair Value	0	0		0
Total, Fair Value	$ 285,687	285,687		0
Unrealized Loss Position, Unrealized Losses [Abstract]
Less Than 12 Months, Unrealized Losses		(1,562)		0
12 Months or Longer, Unrealized Losses		0		0
Total, Unrealized Losses		$ (1,562)		$ 0
Unrealized Loss Position, Number of Positions [Abstract]
Less Than 12 Months, Number of Positions \| Position	94	94		0
12 Months or Longer, Number of Positions \| Position	0	0		0
Total, Number of Positions \| Position	94	94		0
Mortgage backed [Member] \| Government-sponsored enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 260,130	$ 260,130		$ 221,110
Unrealized gains		6,149		11,175
Unrealized losses		1,487		0
Estimated fair value	264,792	264,792		232,285
Mortgage backed [Member] \| U.S. government securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	25,608	25,608
Unrealized gains		1,269
Unrealized losses		75
Estimated fair value	26,802	26,802
State & Municipal [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	125,792	125,792		82,675
Unrealized gains		2,375		4,127
Unrealized losses		1,493		0
Estimated fair value	126,674	126,674		86,802
Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months, Fair Value	125,792	125,792		0
12 Months or Longer, Fair Value	0	0		0
Total, Fair Value	$ 125,792	125,792		0
Unrealized Loss Position, Unrealized Losses [Abstract]
Less Than 12 Months, Unrealized Losses		(1,493)		0
12 Months or Longer, Unrealized Losses		0		0
Total, Unrealized Losses		$ (1,493)		$ 0
Unrealized Loss Position, Number of Positions [Abstract]
Less Than 12 Months, Number of Positions \| Position	193	193		0
12 Months or Longer, Number of Positions \| Position	0	0		0
Total, Number of Positions \| Position	193	193		0
Collateralized Mortgage Obligations [Member]
Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months, Fair Value	$ 625,908	$ 625,908		$ 23
12 Months or Longer, Fair Value	0	0		0
Total, Fair Value	$ 625,908	625,908		23
Unrealized Loss Position, Unrealized Losses [Abstract]
Less Than 12 Months, Unrealized Losses		(6,787)		0
12 Months or Longer, Unrealized Losses		0		0
Total, Unrealized Losses		$ (6,787)		$ 0
Unrealized Loss Position, Number of Positions [Abstract]
Less Than 12 Months, Number of Positions \| Position	28	28		2
12 Months or Longer, Number of Positions \| Position	0	0		0
Total, Number of Positions \| Position	28	28		2
Collateralized Mortgage Obligations [Member] \| Government-sponsored enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 573,487	$ 573,487		$ 399,147
Unrealized gains		2,677		4,418
Unrealized losses		6,747		0
Estimated fair value	569,417	569,417		403,565
Collateralized Mortgage Obligations [Member] \| U.S. government securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	52,421	52,421		44,825
Unrealized gains		970		1,333
Unrealized losses		40		0
Estimated fair value	53,351	53,351		46,158
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	13,409	13,409		11,210
Unrealized gains		2,720		2,832
Unrealized losses		169		88
Estimated fair value	15,960	15,960		13,954
Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months, Fair Value	5,560	5,560		468
12 Months or Longer, Fair Value	211	211		167
Total, Fair Value	$ 5,771	5,771		635
Unrealized Loss Position, Unrealized Losses [Abstract]
Less Than 12 Months, Unrealized Losses		(132)		(6)
12 Months or Longer, Unrealized Losses		(37)		(82)
Total, Unrealized Losses		$ (169)		$ (88)
Unrealized Loss Position, Number of Positions [Abstract]
Less Than 12 Months, Number of Positions \| Position	2	2		1
12 Months or Longer, Number of Positions \| Position	1	1		1
Total, Number of Positions \| Position	3	3		2
Collateralized Mortgage Obligations [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized cost	$ 64,022	$ 64,022		$ 0
Unrealized gains	0			0
Unrealized losses	1,964			0
Total, Fair Value	62,058	62,058		0
Unrealized Loss Position, Fair Value [Abstract]
Less Than 12 Months, Fair Value	64,022	64,022
12 Months or Longer, Fair Value	0	0
Total, Fair Value	$ 64,022	64,022
Unrealized Loss Position, Unrealized Losses [Abstract]
Less Than 12 Months, Unrealized Losses		(1,964)
12 Months or Longer, Unrealized Losses		0
Total, Unrealized Losses		$ (1,964)
Unrealized Loss Position, Number of Positions [Abstract]
Less Than 12 Months, Number of Positions \| Position	5	5
12 Months or Longer, Number of Positions \| Position	0	0
Total, Number of Positions \| Position	5	5
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Securities held to maturity	$ 64,022	$ 64,022		0
Held-to-maturity Securities, Debt Maturities, Fair Value [Abstract]
Total, Fair Value	$ 62,058	$ 62,058		$ 0

Reclassification Adjustments Out of Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain (Loss) on Sale of Securities, Net	$ (61)	$ 97	$ 1,084	$ 552
Salaries and employee benefits	29,160	24,992	56,207	51,717
Income tax expense	7,424	5,683	10,781	11,536
Net Income	16,916	13,257	24,565	26,907
Total reclassification during the period, net of tax	463	453	272	696
Accumulated Net Unrealized Investment Gain (Loss) [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain (Loss) on Sale of Securities, Net	61	(97)	(1,084)	(552)
Income tax expense	(24)	39	434	221
Net Income	37	(58)	(650)	(331)
Accumulated Defined Benefit Plans Adjustment [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense	284	345	614	686
Net Income	426	511	922	1,027
Accumulated Defined Benefit Plans Adjustment [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member] \| Amortization of net gains [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	765	911	1,647	1,824
Accumulated Defined Benefit Plans Adjustment [Member] \| Reclassification out of Accumulated Other Comprehensive Income [Member] \| Amortization of prior service costs [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	$ (55)	$ (55)	$ (111)	$ (111)