Century Bancorp (CNBKA) 10-Q8 May 142014 Q1 Quarterly reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014	Apr. 30, 2014	Apr. 30, 2014
	Mar. 31, 2014	Class A Common Stock [Member]	Class B Common Stock [Member]
Document Information [Line Items]	'	'	'
Document Type	'10-Q	'	'
Amendment Flag	'false	'	'
Document Period End Date	31-Mar-14	'	'
Document Fiscal Year Focus	'2014	'	'
Document Fiscal Period Focus	'Q1	'	'
Trading Symbol	'CNBKA	'	'
Entity Registrant Name	'CENTURY BANCORP INC	'	'
Entity Central Index Key	'0000812348	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Filer Category	'Accelerated Filer	'	'
Entity Common Stock, Shares Outstanding	'	3,582,529	1,974,180

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Assets	'	'
Cash and due from banks	$80,087	$59,956
Federal funds sold and interest-bearing deposits in other banks	83,306	34,722
Total cash and cash equivalents	163,393	94,678
Short-term investments	4,625	4,617
Securities available-for-sale, amortized cost $474,586 and $465,943, respectively	473,302	464,245
Securities held-to-maturity, fair value $1,468,731 and $1,464,449, respectively	1,478,450	1,487,884
Federal Home Loan Bank of Boston stock, at cost	18,872	18,072
Loans, net:	'	'
Commercial and industrial	95,775	92,402
Construction and land development	25,928	33,058
Commercial real estate	708,551	713,327
Residential real estate	290,465	286,041
Home equity	133,800	130,277
Consumer and other	9,542	9,658
Total loans, net	1,264,061	1,264,763
Less: allowance for loan losses	21,259	20,941
Net loans	1,242,802	1,243,822
Bank premises and equipment	23,450	23,400
Accrued interest receivable	6,338	6,539
Goodwill	2,714	2,714
Other assets	86,101	85,183
Total assets	3,500,047	3,431,154
Deposits:	'	'
Demand deposits	489,679	475,862
Savings and NOW deposits	1,018,871	992,796
Money Market Accounts	874,264	864,957
Time deposits	381,199	382,224
Total deposits	2,764,013	2,715,839
Securities sold under agreements to repurchase	210,650	214,440
Other borrowed funds	272,644	255,144
Subordinated debentures	36,083	36,083
Due to broker	1,000	'
Other liabilities	33,575	33,176
Total liabilities	3,317,965	3,254,682
Stockholders' Equity	'	'
Preferred stock - $1.00 par value; 100,000 shares authorized; no shares issued and outstanding	'	'
Additional paid-in capital	11,934	11,932
Retained earnings	185,130	180,747
Stockholders' equity before adjustment of accumulated other comprehensive (income) loss	202,621	198,235
Unrealized losses on securities available-for-sale, net of taxes	-802	-1,045
Unrealized losses on securities transferred to held-to-maturity, net of taxes	-12,743	-13,667
Pension liability, net of taxes	-6,994	-7,051
Total accumulated other comprehensive loss, net of taxes	-20,539	-21,763
Total stockholders' equity	182,082	176,472
Total liabilities and stockholders' equity	3,500,047	3,431,154
Class A Common Stock [Member]	'	'
Stockholders' Equity	'	'
Common stock value	3,583	3,580
Total stockholders' equity	3,583	3,580
Class B Common Stock [Member]	'	'
Stockholders' Equity	'	'
Common stock value	1,974	1,976
Total stockholders' equity	$1,974	$1,976

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Amortized cost	$474,586	$465,943
Held-to-maturity securities, fair value	$1,468,731	$1,464,449
Preferred stock, par value	$1	$1
Preferred stock, shares authorized	100,000	100,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Class A Common Stock [Member]	'	'
Common stock, par value	$1	$1
Common stock, shares authorized	10,000,000	10,000,000
Common stock, shares issued	3,582,479	3,580,404
Class B Common Stock [Member]	'	'
Common stock, par value	$1	$1
Common stock, shares authorized	5,000,000	5,000,000
Common stock, shares issued	1,974,180	1,976,180

Consolidated_Statements_of_Inc

Consolidated Statements of Income (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Interest income	'	'
Loans	$12,449	$11,881
Securities held-to-maturity	7,780	1,520
Securities available-for-sale	820	5,617
Federal funds sold and interest-bearing deposits in other banks	82	119
Total interest income	21,131	19,137
Interest expense	'	'
Savings and NOW deposits	609	610
Money market accounts	639	532
Time deposits	1,085	1,334
Securities sold under agreements to repurchase	101	90
Other borrowed funds and subordinated debentures	2,183	2,026
Total interest expense	4,617	4,592
Net interest income	16,514	14,545
Provision for loan losses	600	750
Net interest income after provision for loan losses	15,914	13,795
Other operating income	'	'
Service charges on deposit accounts	2,034	1,942
Lockbox fees	777	772
Net gains on sales of investments	'	883
Gains on sales of mortgage loans held for sale	7	170
Other income	652	667
Total other operating income	3,470	4,434
Operating expenses	'	'
Salaries and employee benefits	8,875	8,618
Occupancy	1,442	1,282
Equipment	572	582
FDIC assessments	480	400
Other	2,790	2,583
Total operating expenses	14,159	13,465
Income before income taxes	5,225	4,764
Provision for income taxes	293	288
Net income	4,932	4,476
Class A Common Stock [Member]	'	'
Operating expenses	'	'
Net income	3,867	3,502
Share data:	'	'
Weighted average number of shares outstanding, basic	3,582,421	3,569,546
Weighted average number of shares outstanding, diluted	5,558,177	5,557,365
Basic earnings per share	$1.08	$0.98
Diluted earnings per share	$0.89	$0.81
Class B Common Stock [Member]	'	'
Operating expenses	'	'
Net income	$1,065	$974
Share data:	'	'
Weighted average number of shares outstanding, basic	1,974,180	1,986,880
Weighted average number of shares outstanding, diluted	1,974,180	1,986,880
Basic earnings per share	$0.54	$0.49
Diluted earnings per share	$0.54	$0.49

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Statement Of Income And Comprehensive Income [Abstract]	'	'
Net income	$4,932	$4,476
Unrealized gains (losses) on securities:	'	'
Unrealized gains (losses) arising and transferred during period	243	-2,233
Less: reclassification adjustment for gains included in net income	'	-883
Total unrealized gains (losses) on securities	243	-3,116
Accretion of net unrealized losses transferred	924	'
Defined benefit pension plans:	'	'
Amortization of prior service cost and loss included in net periodic benefit cost	57	173
Other comprehensive income (loss)	1,224	-2,943
Comprehensive income	$6,156	$1,533

Consolidated_Statements_of_Cha

Consolidated Statements of Changes in Shareholders' Equity (USD $)	Total	Class A Common Stock [Member]	Class B Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]
In Thousands, unless otherwise specified	Total	Class A Common Stock [Member]	Class B Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Class A Common Stock [Member]	Class B Common Stock [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning balance at Dec. 31, 2012	$179,990	$3,568	$1,986	$11,891	$162,892	'	'	($347)
Net income	4,476	3,502	974	'	4,476	'	'	'
Other comprehensive income, net of tax:	'	'	'	'	'	'	'	'
Unrealized holding (losses) gains arising during period, net of taxes	-3,116	'	'	'	'	'	'	-3,116
Pension liability adjustment, net of taxes	173	'	'	'	'	'	'	173
Stock options exercised	42	2	'	40	'	'	'	'
Cash dividends	'	-428	-119	'	'	-428	-119	'
Ending balance at Mar. 31, 2013	181,018	3,570	1,986	11,931	166,821	'	'	-3,290
Beginning balance at Dec. 31, 2013	176,472	3,580	1,976	11,932	180,747	'	'	-21,763
Net income	4,932	3,867	1,065	'	4,932	'	'	'
Other comprehensive income, net of tax:	'	'	'	'	'	'	'	'
Unrealized holding (losses) gains arising during period, net of taxes	243	'	'	'	'	'	'	243
Unrealized losses accretion on securities transferred to held-to-maturity, net of in taxes	924	'	'	'	'	'	'	924
Pension liability adjustment, net of taxes	57	'	'	'	'	'	'	57
Conversion of class B common stock to class A common stock	'	2	-2	'	'	'	'	'
Stock options exercised	3	1	'	2	'	'	'	'
Cash dividends	'	-430	-119	'	'	-430	-119	'
Ending balance at Mar. 31, 2014	$182,082	$3,583	$1,974	$11,934	$185,130	'	'	($20,539)

Consolidated_Statements_of_Cha1

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Unrealized holding (losses) gains arising during period, taxes	$170	$2,023
Unrealized losses accretion on securities transferred to held-to-maturity, taxes	583	'
Realized net gains	'	883
Pension liability adjustment, taxes	$38	$117
Conversion of class B common stock to class A common stock, shares	2,000	'
Stock options exercised, shares	75	1,600
Class A Common Stock [Member]	'	'
Cash dividends paid, per share	$0.12	$0.12
Class B Common Stock [Member]	'	'
Cash dividends paid, per share	$0.06	$0.06

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:	'	'
Net income	$4,932	$4,476
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Mortgage loans originated for sale	-13,383	-13,666
Proceeds from mortgage loans sold	570	10,865
Gain on sales of mortgage loans held for sale	-7	-170
Net gain on sales of investments	'	-883
Provision for loan losses	600	750
Deferred income taxes	-744	-441
Net depreciation and amortization	867	1,619
Decrease (increase) in accrued interest receivable	201	-200
Increase in other assets	-998	-3,764
Increase in other liabilities	493	1,688
Net cash (used in) provided by operating activities	-7,469	274
CASH FLOWS FROM INVESTING ACTIVITIES:	'	'
Proceeds from maturities of short-term investments	1,061	6,317
Purchase of short-term investments	-1,069	-1,061
Proceeds from calls/maturities of securities available-for-sale	36,157	90,591
Proceeds from sales of securities available-for-sale	'	87,570
Purchase of securities available-for-sale	-44,658	-145,429
Proceeds from calls/maturities of securities held-to-maturity	41,692	14,811
Purchase of securities held-to-maturity	-30,957	'
Net decrease (increase) in loans	13,256	-23,194
Capital expenditures	-636	-364
Net cash provided by investing activities	14,846	29,241
CASH FLOWS FROM FINANCING ACTIVITIES:	'	'
Net (decrease) increase in time deposits	-1,025	22,997
Net increase in demand, savings, money market and NOW deposits	49,199	57,805
Net proceeds from exercise of stock options	3	42
Cash dividends	-549	-547
Net decrease in securities sold under agreements to repurchase	-3,790	-4,310
Net increase (decrease) in other borrowed funds	17,500	-13,000
Net cash provided by financing activities	61,338	62,987
Net increase in cash and cash equivalents	68,715	92,502
Cash and cash equivalents at beginning of period	94,678	152,283
Cash and cash equivalents at end of period	163,393	244,785
Cash paid during the period for:	'	'
Cash paid during the period for interest	4,583	4,594
Cash paid during the period for income taxes	171	345
Change in unrealized (losses) gains on securities available-for-sale, net of taxes	243	-3,116
Change in unrealized losses on securities transferred to held-to-maturity, net of taxes	924	'
Pension liability adjustment, net of taxes	57	173
Due to broker	$1,000	$10,019

Basis_of_Financial_Statement_P

Basis of Financial Statement Presentation	3 Months Ended
Basis of Financial Statement Presentation	Mar. 31, 2014
Accounting Policies [Abstract]	'
Basis of Financial Statement Presentation	'
	Note 1. Basis of Financial Statement Presentation
	The consolidated financial statements include the accounts of Century Bancorp, Inc. (the “Company”) and its wholly owned subsidiary, Century Bank and Trust Company (the “Bank”). The consolidated financial statements also include the accounts of the Bank’s wholly owned subsidiaries, Century Subsidiary Investments, Inc. (“CSII”), Century Subsidiary Investments, Inc. II (“CSII II”), Century Subsidiary Investments, Inc. III (“CSII III”) and Century Financial Services Inc. (“CFSI”). CSII, CSII II, and CSII III are engaged in buying, selling and holding investment securities. CFSI has the power to engage in financial agency, securities brokerage, and investment and financial advisory services and related securities credit. The Company also owns 100% of Century Bancorp Capital Trust II (“CBCT II”). The entity is an unconsolidated subsidiary of the Company.
	All significant intercompany accounts and transactions have been eliminated in consolidation. The Company provides a full range of banking services to individual, business and municipal customers in Massachusetts. As a bank holding company, the Company is subject to the regulation and supervision of the Federal Reserve Board. The Bank, a state chartered financial institution, is subject to supervision and regulation by applicable state and federal banking agencies, including the Federal Reserve Board, the Federal Deposit Insurance Corporation (the “FDIC”) and the Commonwealth of Massachusetts Commissioner of Banks. The Bank is also subject to various requirements and restrictions under federal and state law, including requirements to maintain reserves against deposits, restrictions on the types and amounts of loans that may be granted and the interest that may be charged thereon, and limitations on the types of investments that may be made and the types of services that may be offered. Various consumer laws and regulations also affect the operations of the Bank. In addition to the impact of regulation, commercial banks are affected significantly by the actions of the Federal Reserve Board as it attempts to control the money supply and credit availability in order to influence the economy. All aspects of the Company’s business are highly competitive. The Company faces aggressive competition from other lending institutions and from numerous other providers of financial services. The Company has one reportable operating segment.
	The financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America and general practices within the banking industry. In preparing the financial statements, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities as of the date of the balance sheet and revenues and expenses for the period. Actual results could differ from those estimates. The Company’s quarterly report on Form 10-Q should be read in conjunction with the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2013, as filed with the Securities and Exchange Commission.
	Material estimates that are susceptible to change in the near term relate to the allowance for loan losses. Management believes that the allowance for loan losses is adequate based on independent appraisals and review of other factors, including historical charge-off rates with additional allocations based on risk factors for each category and general economic factors. While management uses available information to recognize loan losses, future additions to the allowance for loan losses may be necessary based on changes in economic conditions. In addition, regulatory agencies periodically review the Company’s allowance for loan losses. Such agencies may require the Company to recognize additions to the allowance for loan losses based on their judgments about information available to them at the time of their examination.
	Certain reclassifications are made to prior-year amounts whenever necessary to conform with the current-year presentation.

Recent_Market_Developments

Recent Market Developments	3 Months Ended
Recent Market Developments	Mar. 31, 2014
Text Block [Abstract]	'
Recent Market Developments	'
	Note 2. Recent Market Developments
	The financial services industry continues to face challenges in the aftermath of the recent national and global economic crisis. Since June 2009, the U.S. economy has been recovering from the most severe recession and financial crisis since the Great Depression. There have been some improvements in private sector employment, industrial production and U.S. exports; nevertheless, the pace of economic recovery has been slow. Financial markets have improved since the depths of the crisis but are still unsettled and volatile. There is continued concern about the U.S. economic outlook.
	On July 21, 2010, the Dodd-Frank Wall Street Reform and Consumer Protection Act (the “Act”) became law. The Act was intended to address many issues arising in the recent financial crisis and is exceedingly broad in scope, affecting many aspects of bank and financial market regulation. The Act requires, or permits by implementing regulation, enhanced prudential standards for banks and bank holding companies inclusive of capital, leverage, liquidity, concentration and exposure measures. In addition, traditional bank regulatory principles such as restrictions on transactions with affiliates and insiders were enhanced. The Act also contains reforms of consumer mortgage lending practices and creates a Bureau of Consumer Financial Protection, which is granted broad authority over consumer financial practices of banks and others. It is expected as the specific new or incremental requirements applicable to the Company become effective that the costs and difficulties of remaining compliant with all such requirements will increase. The Act broadens the base for FDIC assessments to average consolidated assets less tangible equity of financial institutions and also permanently raises the current standard maximum FDIC deposit insurance amount to $250,000. The Act extended unlimited deposit insurance on non-interest bearing transaction accounts through December 31, 2012. In addition, the Act added a new Section 13 to the Bank Holding Company Act, the so-called “Volcker Rule,” (the “Rule”) which generally restricts certain banking entities such as the Company and its subsidiaries or affiliates, from engaging in proprietary trading activities and owning equity in or sponsoring any private equity or hedge fund. The Rule became effective July 21, 2012. The final implementing regulations for the Rule were issued by various regulatory agencies in December, 2013 and under an extended conformance regulation compliance must be achieved by July 21, 2015. Under the Rule, the Company may be restricted from engaging in proprietary trading, investing in third party hedge or private equity funds or sponsoring new funds unless it qualifies for an exemption from the rule. The Company has little involvement in prohibited proprietary trading or investment activities in covered funds and the Company does not expect that complying with the requirements of the Rule will have any material effect on the Company’s financial condition or results of operation.
	On September 29, 2009, the FDIC adopted a Notice of Proposed Rulemaking (NPR) that would require insured institutions to prepay their estimated quarterly risk-based assessments for the fourth quarter of 2009 and for all of 2010, 2011 and 2012. The FDIC Board voted to adopt a uniform three-basis point increase in assessment rates effective on January 1, 2011, and extend the restoration period from seven to eight years. This rule was finalized on November 2, 2009. The Company’s quarterly risk-based deposit insurance assessments were paid from this amount until June 30, 2013. The Company received a refund of $2.4 million of prepaid FDIC assessments in June 2013.
	Federal banking regulators have issued risk-based capital guidelines, which assign risk factors to asset categories and off-balance-sheet items. Also, the Basel Committee has issued capital standards entitled “Basel III: A global regulatory framework for more resilient banks and banking systems” (“Basel III”). The Federal Reserve Board has finalized its rule implementing the Basel III regulatory capital framework. The rule, that will come into effect in January 2015, sets the Basel III minimum regulatory capital requirements for all organizations. It includes a new common equity Tier I ratio of 4.5 percent of risk-weighted assets, raises the minimum Tier I capital ratio from 4 percent to 6 percent of risk-weighted assets and would set a new conservation buffer of 2.5 percent of rick-weighted assets. The Company has analyzed the final rules; the implementation of the framework will not have a material impact on the Company’s financial condition or results of operations.
	The Governor of Massachusetts has proposed a tax plan that would modify existing income tax rules. The governor’s plan is part of his budget recommendations for fiscal year 2015, and will subject security corporations to the same tax base and rate as regular business corporations. The proposed tax changes would take effect as of January 1, 2015. The Company is currently analyzing the financial impact of the proposed changes.

Stock_Option_Accounting

Stock Option Accounting	3 Months Ended
Stock Option Accounting	Mar. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Stock Option Accounting	'
	Note 3. Stock Option Accounting
	Stock option activity under the Company’s stock option plan for the three months ended March 31, 2014 is as follows:


		Amount			Weighted
					Average
					Exercise Price
	Shares under option:
	Outstanding at beginning of year		20,375		$	31.82
	Exercised		(75	)		31.83
	Forfeited		—			—

	Outstanding at end of period		20,300		$	31.82

	Exercisable at end of period		20,300		$	31.82

	Available to be granted at end of period		224,884

	On March 31, 2014, the outstanding options to purchase 20,300 shares of Class A common stock have exercise prices between $31.60 and $31.83, with a weighted average exercise price of $31.82 and a weighted average remaining contractual life of 0.5 years. The intrinsic value of options exercisable at March 31, 2014 had an aggregate value of $46,284. The intrinsic value of options exercised at March 31, 2014 had an aggregate value of $171.
	The Company uses the fair value method to account for stock options. All of the Company’s stock options are vested and there were no options granted during the first quarter of 2014.

Securities_AvailableforSale

Securities Available-for-Sale	3 Months Ended
Securities Available-for-Sale	Mar. 31, 2014
Text Block [Abstract]	'
Securities Available-for-Sale	'
	Note 4. Securities Available-for-Sale


			March 31, 2014												December 31, 2013
			Amortized			Gross			Gross			Fair			Amortized			Gross		Gross		Fair
			Cost			Unrealized			Unrealized			Value			Cost			Unrealized		Unrealized		Value
						Gains			Losses									Gains		Losses
			( In thousands)
	U.S. Treasury		$	1,998		$	2		$	—		$	2,000		$	1,997		$	1	$	—	$	1,998
	U.S. Government Sponsored Enterprises			—			—			—			—			9,995			9		—		10,004
	Small Business Administration			7,109			40			—			7,149			7,270			32		—		7,302
	U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities			426,521			825			1,331			426,015			404,103			588		1,501		403,190
	Privately Issued Residential Mortgage Backed Securities			2,189			18			20			2,187			2,294			6		23		2,277
	Obligations Issued by States and Political Subdivisions			34,063			8			870			33,201			37,578			15		870		36,723

	Other Debt Securities			2,300			—			120			2,180			2,300			—		125		2,175
	Equity Securities			406			164			—			570			406			170		—		576


	Total		$	474,586		$	1,057		$	2,341		$	473,302		$	465,943		$	821	$	2,519	$	464,245


	During the third quarter of 2013, securities available-for-sale with an amortized cost of $1,012,370,000 were transferred to securities held-to-maturity at their fair value of $987,037,000 in response to rising interest rates. Rising interest rates have the potential to increase unrealized losses on the available-for-sale portfolio. The transfer was implemented to lessen the effects of rising interest rates.
	Included in U.S. Government Sponsored Enterprise Securities and U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities are securities at fair value pledged to secure public deposits and repurchase agreements amounting to $357,512,000 and $368,137,000 at March 31, 2014 and December 31, 2013, respectively. Also included in securities available-for-sale are securities pledged for borrowing at the Federal Home Loan Bank of Boston amounting to $30,744,000 and $12,214,000 at March 31, 2014 and December 31, 2013, respectively. There were no realized gains on sales of investments for the three months ended March 31, 2014. The Company realized gross gains of $883,000 from the proceeds of $87,570,000 from the sales of available-for-sale securities for the three months ended March 31, 2013.
	Debt securities of Government Sponsored Enterprises primarily refer to debt securities of Fannie Mae and Freddie Mac.
	The following table shows the maturity distribution of the Company’s securities available-for-sale at March 31, 2014.


			Amortized			Fair
			Cost			Value
			( In thousands)
	Within one year		$	29,408		$	29,429
	After one but within five years			193,847			193,971
	After five but within ten years			230,394			229,759
	More than 10 years			19,031			18,193
	Non-maturing			1,906			1,950

	Total		$	474,586		$	473,302

	The weighted average remaining life of investment securities available-for-sale at March 31, 2014 was 5.2 years. The contractual maturities, which were used in the table above, of mortgage-backed securities, will differ from the actual maturities, due to the ability of the issuers to prepay underlying obligations.
	As of March 31, 2014 and December 31, 2013, management concluded that the unrealized losses of its investment securities are temporary in nature since they are not related to the underlying credit quality of the issuers, and the Company does not intend to sell these debt securities and it is not more likely than not that it will be required to sell these debt securities before the anticipated recovery of its remaining amortized cost. In making its other-than-temporary impairment evaluation, the Company considered the fact that the principal and interest on these securities are from issuers that are investment grade. The change in the unrealized losses on the state and municipal securities and the nonagency mortgage-backed securities was primarily caused by changes in credit spreads and liquidity issues in the marketplace.
	The unrealized loss on U.S. Government Sponsored Enterprises and U.S. Government Sponsored Enterprises Mortgage Backed Securities related primarily to interest rates and not credit quality and because the Company has the ability and intent to hold these investments until recovery of fair value, which may be maturity. The Company does not consider these investments to be other-than-temporarily impaired.

	In evaluating the underlying credit quality of a security, management considers several factors such as the credit rating of the obligor and the issuer, if applicable. Internal reviews of issuer financial statements are performed as deemed necessary. In the case of privately issued mortgage-backed securities, the performance of the underlying loans is analyzed as deemed necessary to determine the estimated future cash flows of the securities. Factors considered include the level of subordination, current and estimated future default rates, current and estimated prepayment rates, estimated loss severity rates, geographic concentrations and origination dates of underlying loans. In the case of marketable equity securities, the severity of the unrealized loss, the length of time the unrealized loss has existed, and the issuer’s financial performance are considered.
	The following table shows the temporarily impaired securities of the Company’s available-for-sale portfolio at March 31, 2014. This table shows the unrealized market loss of securities that have been in a continuous unrealized loss position for 12 months or less and a continuous loss position for 12 months and longer. There are 32 and 10 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 240 holdings at March 31, 2014.


			March 31, 2014
			Less than 12 months						12 months or longer						Total
	Temporarily Impaired Investments		Fair Value			Unrealized			Fair Value			Unrealized			Fair Value			Unrealized
	Temporarily Impaired Investments		Fair Value			Losses			Fair Value			Losses			Fair Value			Losses
			(In thousands)
	U.S. Government Sponsored Enterprises		$	—		$	—		$	—		$	—		$	—		$	—
	U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities			208,531			980			56,658			351			265,189			1,331
	Privately Issued Residential Mortgage Backed Securities			800			20			—			—			800			20
	Obligations Issued by States and Political Subdivisions			—			—			3,820			870			3,820			870
	Other Debt Securities			—			—			1,380			120			1,380			120

	Total temporarily impaired securities		$	209,331		$	1,000		$	61,858		$	1,341		$	271,189		$	2,341

	The following table shows the temporarily impaired securities of the Company’s available-for-sale portfolio at December 31, 2013. This table shows the unrealized market loss of securities that have been in a continuous unrealized loss position for 12 months or less and a continuous loss position for 12 months and longer. There are 20 and 7 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 458 holdings at December 31, 2013.


		December 31, 2013
		Less than 12 months						12 months or longer						Total
Temporarily Impaired Investments		Fair Value			Unrealized			Fair Value			Unrealized			Fair Value			Unrealized
Temporarily Impaired Investments		Fair Value			Losses			Fair Value			Losses			Fair Value			Losses
		(In thousands)
U.S. Government Sponsored Enterprises		$	—		$	—		$	—		$	—		$	—		$	—
U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities			289,709			1, 352			24,557			149			314,266			1,501
Privately Issued Residential Mortgage Backed Securities			1,486			23			—			—			1,486			23
Obligations Issued by States and Political Subdivisions			—			—			3,820			870			3,820			870
Other Debt Securities			—			—			1,376			125			1,376			125

Total temporarily impaired securities		$	291,195		$	1,375		$	29,753		$	1,144		$	320,948		$	2,519

Investment_Securities_HeldtoMa

Investment Securities Held-to-Maturity	3 Months Ended
Investment Securities Held-to-Maturity	Mar. 31, 2014
Text Block [Abstract]	'
Investment Securities Held-to-Maturity	'
	Note 5. Investment Securities Held-to-Maturity


		March 31, 2014								December 31, 2013
		Amortized		Gross		Gross		Estimated		Amortized		Gross		Gross		Estimated
		Cost		Unrealized		Unrealized		Fair		Cost		Unrealized		Unrealized		Fair
				Gains		Losses		Value				Gains		Losses		Value
		(In thousands)
	U.S. Government Sponsored Enterprises	$	292,325	$	512	$	1,653	$	291,184	$	291,779	$	185	$	5,043	$	286,921
	U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities		1,186,125		4,949		13,527		1,177,547		1,196,105		2,239		20,816		1,177,528

	Total	$	1,478,450	$	5,461	$	15,180	$	1,468,731	$	1,487,884	$	2,424	$	25,859	$	1,464,449

	Included in U.S. Government and Agency Securities are securities pledged to secure public deposits and repurchase agreements at fair value amounting to $751,754,000 and $732,144,000 at March 31, 2014 and December 31, 2013, respectively. Also included are securities pledged for borrowing at the Federal Home Loan Bank of Boston at fair value amounting to $514,421,000 and $510,060,000 at March 31, 2014 and December 31, 2013, respectively.
	At March 31, 2014 and December 31, 2013, all mortgage-backed securities are obligations of U.S. Government Agencies and Government Sponsored Enterprises. Government Sponsored Enterprises primarily refer to debt securities of Fannie Mae and Freddie Mac.
	The following table shows the maturity distribution of the Company’s securities held-to-maturity at March 31, 2014.


		Amortized		Fair
		Cost		Value
		( In thousands)
	Within one year	$	4,830	$	4,849
	After one but within five years		845,948		842,706
	After five but within ten years		626,601		620,086
	More than ten years		1,071		1 ,090

	Total	$	1,478,450	$	1,468,731

	The weighted average remaining life of investment securities held-to-maturity at March 31, 2014 was 5.0 years. Included in the weighted average remaining life calculation at March 31, 2014 were $224,667,000 of U.S. Government Sponsored Enterprises obligations that are callable at the discretion of the issuer. The actual maturities, which were used in the table above, of mortgage-backed securities, will differ from the contractual maturities, due to the ability of the issuers to prepay underlying obligations.
	As of March 31, 2014 and December 31, 2013, management concluded that the unrealized losses of its investment securities are temporary in nature since they are not related to the underlying credit quality of the issuers, and the Company does not intend to sell these debt securities and it is not likely that it will be required to sell these debt securities before the anticipated recovery of their remaining amortized costs. In making its other-than-temporary impairment evaluation, the Company considered the fact that the principal and interest on these securities are from issuers that are investment grade.
	The unrealized loss on U.S. Government Agency and Sponsored Enterprises Mortgage-Backed Securities related primarily to interest rates and not credit quality, and because the Company does not intend to sell any of these securities and it is not likely that it will be required to sell these securities before the anticipated recovery of the remaining amortized cost, the Company does not consider these investments to be other-than-temporarily impaired at March 31, 2014 and December 31, 2013.
	In evaluating the underlying credit quality of a security, management considers several factors such as the credit rating of the obligor and the issuer, if applicable. Internal reviews of issuer financial statements are performed as deemed necessary.

	The following table shows the temporarily impaired securities of the Company’s held-to-maturity portfolio at March 31, 2014. This table shows the unrealized market loss of securities that have been in a continuous unrealized loss position for 12 months or less and a continuous loss position for 12 months and longer. There are 134 and 21 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 303 holdings at March 31, 2014.


		March 31, 2014
		Less Than 12 Months				12 Months or Longer				Total
	Temporarily Impaired Investments	Fair Value		Unrealized		Fair Value		Unrealized		Fair Value		Unrealized
	Temporarily Impaired Investments	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
		(Dollars in thousands)
	U.S. Government Sponsored Enterprises	$	164,174	$	1,653	$	—	$	—	$	164,174	$	1,653
	U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities		607,346		10,558		129,838		2,969		737,184		13,527

	Total temporarily impaired securities	$	771,520	$	12,211	$	129,838	$	2,969	$	901,358	$	15,180

	The following table shows the temporarily impaired securities of the Company’s held-to-maturity portfolio at December 31, 2013. This table shows the unrealized market loss of securities that have been in a continuous unrealized loss position for 12 months or less and a continuous loss position for 12 months and longer. There are 3 and 1 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 96 holdings at December 31, 2013.


		December 31, 2013
		Less Than 12 Months				12 Months or Longer				Total
	Temporarily Impaired Investments	Fair Value		Unrealized		Fair Value		Unrealized		Fair Value		Unrealized
	Temporarily Impaired Investments	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
		( In thousands)
	U.S. Government Sponsored Enterprises	$	232,535	$	5,043	$	—	$	—	$	232,535	$	5,043
	U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities		931,180		18,654		80,362		2,162		1,011,542		20,816

	Total temporarily impaired securities	$	1,163,715	$	23,697	$	80,362	$	2,162	$	1,244,077	$	25,859

Allowance_for_Loan_Losses

Allowance for Loan Losses	3 Months Ended
Allowance for Loan Losses	Mar. 31, 2014
Receivables [Abstract]	'
Allowance for Loan Losses	'
	Note 6. Allowance for Loan Losses
	The Company maintains an allowance for loan losses in an amount determined by management on the basis of the character of the loans, loan performance, the financial condition of borrowers, the value of collateral securing loans and other relevant factors.
	The following table summarizes the changes in the Company’s allowance for loan losses for the periods indicated.


			Three months ended
			March 31,
			2014				2013
			(in thousands)
	Allowance for loan losses, beginning of period		$	20,941			$	19,197
	Loans charged off			(429	)			(371	)
	Recoveries on loans previously charged-off			147				183

	Net charge-offs			(282	)			(188	)
	Provision charged to expense			600				750

	Allowance for loan losses, end of period		$	21,259			$	19,759


	Further information pertaining to the allowance for loan losses for the three months ending March 31, 2014 follows:


			Construction				Commercial				Commercial				Residential				Consumer				Home				Unallocated			Total
			and Land				and				Real				Real								Equity
			Development				Industrial				Estate				Estate
			(Dollars in thousands)
	Allowance for loan losses:
	Balance at December 31, 2013		$	2,174			$	2,989			$	11,218			$	2,006			$	432			$	959			$	1,163		$	20,941
	Charge-offs			(250	)			—				—				—				(179	)			—				—			(429	)
	Recoveries			—				24				1				5				116				1				—			147
	Provision			(99	)			77				655				(138	)			56				(58	)			107			600

	Ending balance at March 31, 2014		$	1,825			$	3,090			$	11,874			$	1,873			$	425			$	902			$	1,270		$	21,259

	Amount of allowance for loan losses for loans deemed to be impaired		$	25			$	358			$	382			$	122			$	—			$	94			$	—			981

	Amount of allowance for loan losses for loans not deemed to be impaired		$	1,800			$	2,732			$	11,492			$	1,751			$	425			$	808			$	1,270		$	20,278


	Loans:
	Ending balance		$	25,928			$	95,775			$	708,551			$	290,465			$	9,542			$	133,800			$	—		$	1,264,061

	Loans deemed to be impaired		$	358			$	1,129			$	4,408			$	998			$	—			$	94			$	—		$	6,987

	Loans not deemed to be impaired		$	25,570			$	94,646			$	704,143			$	289,467			$	9,542			$	133,706			$	—		$	1,257,074

	Further information pertaining to the allowance for loan losses for three months ending March 31, 2013 follows:


			Construction				Commercial				Commercial				Residential				Consumer				Home				Unallocated			Total
			and Land				and				Real				Real								Equity
			Development				Industrial				Estate				Estate
			(Dollars in thousands)
	Allowance for loan losses:

	Balance at December 31, 2012		$	3,041			$	3,118			$	9,065			$	1,994			$	333			$	886			$	760		$	19,197
	Charge-offs			—				(226	)			—				—				(145	)			—				—			(371	)
	Recoveries			—				65				2				2				114								—			183
	Provision			158				566				(288	)			75				55				(53	)			237			750

	Ending balance at March 31, 2013		$	3,199			$	3,523			$	8,779			$	2,071			$	357			$	833			$	997		$	19,759

	Amount of allowance for loan losses for loans deemed to be impaired		$	1,000			$	103			$	396			$	155			$	—			$	96			$	—			1,750

Amount of allowance for loan losses for loans not deemed to be impaired		$	2,199			$	3,420			$	8,383			$	1,916			$	357			$	737			$	997		$	18,009

Loans:
Ending balance		$	34,021			$	110,537			$	570,441			$	292,871			$	7,910			$	121,989			$	—		$	1,137,769

Loans deemed to be impaired		$	1,500			$	1,396			$	2,262			$	1,232			$	—			$	96			$	—		$	6,486

Loans not deemed to be impaired		$	32,521			$	109,141			$	568,179			$	291,639			$	7,910			$	121,893			$	—		$	1,131,283


The Company utilizes a six grade internal loan rating system for commercial real estate, construction and commercial loans as follows:
Loans rated 1-3 (Pass):
Loans in this category are considered “pass” rated loans with low to average risk.
Loans rated 4 (Monitor):
These loans represent classified loans that management is closely monitoring for credit quality. These loans have had or may have minor credit quality deterioration as of March 31, 2014 and December 31, 2013.
Loans rated 5 (Substandard):
Substandard loans represent classified loans that management is closely monitoring for credit quality. These loans have had more significant credit quality deterioration as of March 31, 2014 and December 31, 2013.
Loans rated 6 (Doubtful):
Doubtful loans represent classified loans that management is closely monitoring for credit quality. These loans had more significant credit quality deterioration as of March 31, 2014 and December 31, 2013 and are doubtful for full collection.
Impaired:
Impaired loans represent classified loans that management is closely monitoring for credit quality. A loan is classified as impaired when it is probable that the Company will be unable to collect all amounts due.
The following table presents the Company’s loans by risk rating at March 31, 2014.


		Construction				Commercial				Commercial
		and land				and				real
		development				industrial				estate
		(Dollars in thousands)
Grade:
1-3 (Pass)		$	18,303			$	93,485			$	699,238
4 (Monitor)			7,267				1,120				4,905
5 (Substandard)			—				—				—
6 (Doubtful)			—				—				—
Impaired			358				1,170				4,408

Total		$	25,928			$	95,775			$	708,551

The following table presents the Company’s loans by risk rating at December 31, 2013.


		Construction				Commercial				Commercial
		and land				and				real
		development				industrial				estate
		(Dollars in thousands)
Grade:
1-3(Pass)		$	25,138			$	90,563			$	707,461
4 (Monitor)			7,312				472				1,346
5 (Substandard)			—				—				—
6 (Doubtful)			—				—				—
Impaired			608				1,367				4,520

Total		$	33,058			$	92,402			$	713,327

The Company utilized payment performance as credit quality indicators for residential real estate, consumer and overdrafts, and the home equity portfolio. The indicators are depicted in the table “aging of past due loans,” below.

Further information pertaining to the allowance for loan losses at March 31, 2014 follows:


		Accruing				Non Accrual				Accrual				Total				Current Loans				Total
		30-89 Days								Greater				Past Due
		Past Due								Than
										90 Days
		(Dollars in thousands)
Construction and land development		$	—			$	358			$	—			$	358			$	25,570			$	25,928
Commercial and industrial			467				475				—				942				94,833				95,775
Commercial real estate			2,633				218				—				2,851				705,700				708,551
Residential real estate			229				464				—				693				289,772				290,465
Consumer and overdrafts			1				5				—				6				9,536				9,542
Home equity			470				40				—				510				133,290				133,800

Total		$	3,800			$	1,560			$	—			$	5,360			$	1,258,701			$	1,264,061

Further information pertaining to the allowance for loan losses at December 31, 2013 follows:


		Accruing				Non Accrual				Accrual				Total				Current Loans				Total
		30-89 Days								Greater				Past Due
		Past Due								Than
										90 Days
		(Dollars in thousands)
Construction and land development		$	—			$	500			$	—			$	500			$	32,558			$	33,058
Commercial and industrial			112				706								818				91,584				92,402
Commercial real estate			1,496				306				—				1,802				711,525				713,327
Residential real estate			2,232				1,034				—				3,266				282,775				286,041
Consumer and overdrafts			11				3				—				14				9,644				9,658
Home equity			1,710				—				—				1,710				128,567				130,277

Total		$	5,561			$	2,549			$	—			$	8,110			$	1,256,653			$	1,264,763

A loan is impaired when, based on current information and events, it is probable that a creditor will be unable to collect all amounts due according to the contractual terms of the loan agreement. When a loan is impaired, the Company measures impairment based on the present value of expected future cash flows discounted at the loan’s effective interest rate, except that as a practical expedient, the Company measures impairment based on a loan’s observable market price, or the fair value of the collateral if the loan is collateral dependent. Loans are charged-off when management believes that the collectability of the loan’s principal is not probable. The specific factors that management considers in making the determination that the collectability of the loan’s principal is not probable include; the delinquency status of the loan, the fair value of the collateral, if secured, and the financial strength of the borrower and/or guarantors. For collateral dependent loans, the amount of the recorded investment in a loan that exceeds the fair value of the collateral is charged-off against the allowance for loan losses in lieu of an allocation of a specific allowance amount when such an amount has been identified definitively as uncollectible. The Company’s policy for recognizing interest income on impaired loans is contained within Note 1 of the consolidated financial statements contained in the Company’s Annual Report for the fiscal year ended December 31, 2013.

The following is information pertaining to impaired loans for March 31, 2014:


		Carrying Value				Unpaid				Required				Average				Interest
						Principal				Reserve				Carrying Value				Income
						Balance												Recognized
		(Dollars in thousands)
With no required reserve recorded:
Construction and land development		$	250			$	3,292			$	—			$	437			$	—
Commercial and industrial			11				42				—				116				—
Commercial real estate			55				56				—				41				—
Residential real estate			—				—				—				164				—
Consumer			—				—				—				—				—
Home equity			—				—				—				—				—

Total		$	316			$	3 390			$	—				758			$	—

With required reserve recorded:
Construction and land development		$	108			$	108			$	25				108			$	—
Commercial and industrial			1,118				1,352				358				1,116				8
Commercial real estate			4,353				4,442				382				4,420				32
Residential real estate			998				1,082				122				949				1
Consumer			—				—				—				—				—
Home equity			94				94				94				94				—

Total		$	6,671			$	7,078			$	981			$	6,687			$	41

Total:
Construction and land development		$	358			$	3,400			$	25				545			$	—
Commercial and industrial			1,129				1,394				358				1,232				8
Commercial real estate			4,408				4,498				382				4,461				32
Residential real estate			998				1,082				122				1,113				1
Consumer			—				—				—				—				—
Home equity			94				94				94				94				—

Total		$	6,987			$	10,468			$	981			$	7,445			$	41

The following is information pertaining to impaired loans for March 31, 2013:


		Carrying Value				Unpaid				Required				Average				Interest
						Principal				Reserve				Carrying Value				Income
						Balance												Recognized
		(Dollars in thousands)
With no required reserve recorded:
Construction and land development		$	—			$	—			$	—			$	—			$	—
Commercial and industrial			566				1,058				—				545				—
Commercial real estate			165				198				—				167				—
Residential real estate			319				321				—				102				—
Consumer			—				—				—				—				—
Home equity			—				—				—				—				—

Total		$	1,050			$	1,577			$	—			$	814			$	—

With required reserve recorded:
Construction and land development		$	1,500			$	3,292			$	1,000			$	1,500			$	—
Commercial and industrial			830				1,046				103				840				9
Commercial real estate			2,097				2,146				396				2,105				24
Residential real estate			913				995				155				779				—
Consumer			—				—				—				—				—
Home equity			96				96				96				96				—

Total		$	5,436			$	7,575			$	1,750			$	5,320			$	33

Total:
Construction and land development		$	1,500			$	3,292			$	1,000			$	1,500			$	—
Commercial and industrial			1,396				2,104				103				1,385				9
Commercial real estate			2,262				2,344				396				2,272				24
Residential real estate			1,232				1,316				155				881				—
Consumer			—				—				—				—				—
Home equity			96				96				96				96				—

Total		$	6,486			$	9,152			$	1,750			$	6,134			$	33

There were no troubled debt restructurings occurring during the three month periods ended March 31, 2013 or March 31, 2014.

Reclassifications_Out_of_Accum

Reclassifications Out of Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2014
Text Block [Abstract]	'
Reclassifications Out of Accumulated Other Comprehensive Income	'
	Note 7. Reclassifications Out of Accumulated Other Comprehensive Income (a)
	Amount Reclassified from Accumulated
	Other Comprehensive Income


	Details about Accumulated		Three Months Ended			Three Months Ended			Affected Line Item
	Other Comprehensive		March 31, 2014			March 31, 2013			in the Statement
	Income Components								Where Net Income
									is Presented
	(in thousands)
	Unrealized gains and losses on available-for-sale securities

			$	—		$	883		Net gains on sales of investments
				—			(350	)	Provision for income taxes

			$	—		$	533		Net income


	Accretion of unrealized losses transferred

			$	1,507		$	—		Securities held-to-maturity
				(583	)		—		Provision for income taxes

			$	924		$	—		Net income


	Amortization of defined benefit pension items

	Prior-service costs		$	(3	)(b)	$	(3	)	Salaries and employee benefits
	Actuarial gains (losses)			(92	)(b)		(287	)	Salaries and employee benefits

	Total before tax			(95	)		(290	)	Income before taxes
	Tax (expense) or benefit			38			117		Provision for income taxes

	Net of tax		$	(57	)	$	(173	)	Net income


	Total reclassifications for the period		$	867		$	360		Net income, net of tax


	(a)	Amounts in parentheses indicate debits to profit/loss.
	(b)	These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see employee benefits footnote (Note 9) for additional details).

Earnings_Per_Share_EPS

Earnings Per Share ("EPS")	3 Months Ended
Earnings Per Share ("EPS")	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Earnings Per Share ("EPS")	'
	Note 8. Earnings per Share (“EPS”)
	Class A and Class B shares participate equally in undistributed earnings. Under the Company’s Articles of Organization, the holders of Class A Common Stock are entitled to receive dividends per share equal to at least 200% of dividends paid, if any, from time to time, on each share of Class B Common Stock.
	Diluted EPS includes the dilutive effect of common stock equivalents; basic EPS excludes all common stock equivalents. The only common stock equivalents for the Company are the stock options discussed below. The dilutive effect of these stock options for 2014 and 2013 was an increase of 1,576 and 939 shares, respectively.
	The following table is a reconciliation of basic EPS and diluted EPS for the three months ended March 31,


		2014		2013
	Basic EPS Computation:
	(in thousands except share and per share data)
	Numerator:
	Net income, Class A	$	3,867	$	3,502
	Net income, Class B		1,065		974
	Denominator:
	Weighted average shares outstanding, Class A		3,582,421		3,569,546
	Weighted average shares outstanding, Class B		1,974,180		1,986,880
	Basic EPS, Class A	$	1.08	$	0.98
	Basic EPS, Class B		0.54		0.49

	Diluted EPS Computation:
	Numerator:
	Net income, Class A	$	3,867	$	3,502
	Net income, Class B		1,065		974

	Total net income, for diluted EPS, Class A computation		4,932		4,476
	Denominator:
	Weighted average shares outstanding, basic, Class A		3,582,421		3,569,546
	Weighted average shares outstanding, Class B		1,974,180		1,986,880
	Dilutive effect of Class A stock options		1,576		939

	Weighted average shares outstanding diluted, Class A		5,558,177		5,557,365
	Weighted average shares outstanding, Class B		1,974,180		1,986,880
	Diluted EPS, Class A	$	0.89	$	0.81
	Diluted EPS, Class B		0.54		0.49

Employee_Benefits

Employee Benefits	3 Months Ended
Employee Benefits	Mar. 31, 2014
Compensation And Retirement Disclosure [Abstract]	'
Employee Benefits	'
	Note 9. Employee Benefits
	The Company provides pension benefits to its employees under a noncontributory, defined benefit plan which is funded on a current basis in compliance with the requirements of the Employee Retirement Income Security Act of 1974 (“ERISA”) and recognizes costs over the estimated employee service period.
	The Company also has a Supplemental Executive Insurance/Retirement Plan (the “Supplemental Plan”) which is limited to certain officers and employees of the Company. The Supplemental Plan is accrued on a current basis and recognizes costs over the estimated employee service period.
	Executive officers of the Company and its subsidiaries who have at least one year of
	service may participate in the Supplemental Plan. The Supplemental Plan is voluntary and participants are required to contribute to its cost. Life insurance policies, which are owned by the Company, are purchased covering the lives of each participant.
	Components of Net Periodic Benefit Cost (Credit) for the Three Months Ended March 31,


		Pension Benefits						Supplemental Insurance/
		Pension Benefits						Retirement Plan
		2014			2013			2014		2013
		(In thousands)
	Service cost	$	258		$	299		$	389	$	381
	Interest		367			314			331		267
	Expected return on plan assets		(636	)		(470	)		—		—
	Recognized prior service cost (benefit)		(26	)		(26	)		29		29
	Recognized net actuarial losses		3			158			88		129

	Net periodic benefit (credit)cost	$	(34	)	$	275		$	837	$	806

	Contributions
	The Company currently intends to contribute $1,000,000 to the Pension Plan in 2014. As of March 31, 2014, $460,000 of the contribution had been made. The Company expects to contribute an additional $540,000 by the end of the year.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
Fair Value Measurements	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	Note 10. Fair Value Measurements
	The Company follows FASB ASC 820-10, Fair Value Measurements and Disclosures, (formerly SFAS 157, “Fair Value Measurements,”) which among other things, requires enhanced disclosures about assets and liabilities carried at fair value. ASC 820-10 establishes a hierarchal disclosure framework associated with the level of pricing observability utilized in measuring financial instruments at fair value. The three broad levels of the hierarchy are as follows:
	Level I – Quoted prices are available in active markets for identical assets or liabilities as of the reported date. The type of financial instruments included in Level I are highly liquid cash instruments with quoted prices such as G-7 government, agency securities, listed equities and money market securities, as well as listed derivative instruments.
	Level II – Pricing inputs are other than quoted prices in active markets, which are either directly or indirectly observable as of the reported date. The nature of these financial instruments include cash instruments for which quoted prices are available but traded less frequently, derivative instruments whose fair value have been derived using a model where inputs to the model are directly observable in the market, or can be derived principally from or corroborated by observable market data, and instruments that are fair valued using other financial instruments, the parameters of which can be directly observed. Instruments which are generally included in this category are corporate bonds and loans, mortgage whole loans, municipal bonds and OTC derivatives.

	Level III – Instruments that have little to no pricing observability as of the reported date. These financial instruments do not have two-way markets and are measured using management’s best estimate of fair value, where the inputs into the determination of fair value require significant management judgment or estimation. Instruments that are included in this category generally include certain commercial mortgage loans, certain private equity investments, distressed debt, non-investment grade residual interests in securitizations, as well as certain highly structured OTC derivative contracts.
	The results of the fair value hierarchy as of March 31, 2014, are as follows:


	Financial Instruments Measured at Fair Value on a Recurring Basis:
			Securities AFS Fair Value Measurements Using
			Carrying			Quoted Prices				Significant			Significant
			Value			In Active				Observable			Other
						Markets for				Inputs			Unobservable
						Identical				(Level 2)			Inputs
						Assets							(Level 3)
						(Level 1)
			(In thousands)
	U.S. Treasury		$	2,000		$	—			$	2,000		$	—

	U.S. Government Sponsored Enterprises			—			—				—			—

	SBA Backed Securities			7,149			—				7,149			—
	U.S. Government Agency and Sponsored Mortgage Backed Securities			426,015			—				426,015			—

	Privately Issued Residential Mortgage Backed Securities			2,187			—				2,187			—

	Obligations Issued by States and Political Subdivisions			33,201			—				411			32,790

	Other Debt Securities			2,180			—				2,180			—
	Equity Securities			570			280				—			290

	Total		$	473,302		$	280			$	439,942		$	33,080


	Financial Instruments Measured at Fair Value on a Non-recurring Basis:

	Impaired Loans			1,833			—				—			1,833
	Impaired loan balances represent those collateral dependent loans where management has estimated the credit loss by comparing the loan’s carrying value against the expected realizable fair value of the collateral. Fair value is generally determined through a review process that includes independent appraisals, discounted cash flows, or other external assessments of the underlying collateral, which generally include various Level 3 inputs which are not identifiable. The Company discounts the fair values, as appropriate, based on management’s observations of the local real estate market for loans in this category.
	Appraisals, discounted cash flows and real estate tax assessments are reviewed quarterly. There is no specific policy regarding how frequently appraisals will be updated. Adjustments are made to appraisals and real estate tax assessments based on management’s estimate of changes in real estate values. Within the past twelve months there have been no updated appraisals, however, all impaired loans have been reviewed during the past quarter using either a discounted cash flow analysis or other type of real estate tax assessment. The types of adjustments that are made to specific provisions (credits) relate to impaired loans recognized for the three-month period ended March 31, 2014 amounted to $254,000.

	There were no transfers between level 1 and 2 for the three months ended March 31, 2014. There were no liabilities measured at fair value on a recurring or nonrecurring basis during the three month period ended March 31, 2014.
	The following table presents additional information about assets measured at fair value on a recurring and nonrecurring basis for which the Company has utilized Level 3 inputs to determine fair value (dollars in thousands). Management continues to monitor the assumptions used to value the assets listed below.


	Asset		Fair Value			Valuation Technique		Unobservable Input		Unobservable Input
	Asset		Fair Value			Valuation Technique		Unobservable Input		Value or Range
	Securities AFS(4)		$	33,080		Discounted cash flow		Discount rate		0% -1% (3)
	Impaired Loans			1,833		Appraisal of collateral (1)		Appraisal adjustments (2)		0%-25% discount

	-1	Fair value is generally determined through independent appraisals of the underlying collateral, which generally include various Level 3 inputs which are not identifiable.
	-2	Appraisals may be adjusted by management for qualitative factors such as economic conditions and estimated expenses.
	-3	Weighted averages
	-4	Municipal securities generally have maturities of one year or less and, therefore, the amortized cost equates to the fair value.
	The changes in Level 3 securities for the three-month period ended March 31, 2014 are shown in the table below:


			Auction Rate			Obligations				Equity			Total
			Securities			Issued by States				Securities
						& Political
						Subdivisions
			(In thousands)
	Balance at December 31, 2013		$	3,820		$	32,487			$	290		$	36,597
Purchases			—			7,205				—			7,205
Maturities and calls			—			(10,717	)			—			(10,717	)
Amortization			—			(5	)			—			(5	)
Changes in fair value			—			—				—			—

Balance at March 31, 2014		$	3,820		$	28,970			$	290		$	33,080

The amortized cost of Level 3 securities was $33,951,000 at March 31, 2014 with an unrealized loss of $870,000. The securities in this category are generally equity investments, municipal securities with no readily determinable fair value or failed auction rate securities. Management evaluated the fair value of these securities based on an evaluation of the underlying issuer, prevailing rates and market liquidity.
The changes in Level 3 securities for the three-month period ended March 31, 2013, are shown in the table below:


		Auction Rate			Obligations				Equity			Total
		Securities			Issued by States				Securities
					& Political
					Subdivisions
		(In thousands)
Balance at December 31, 2012		$	3,963		$	49,477			$	342		$	53,782
Purchases			—			6,179				—			6,179
Maturities and calls			—			(9,974	)			—			(9,974	)
Amortization			—			(9	)			—			(9	)
Changes in fair value			—			—				—			—

Balance at March 31, 2013		$	3,963		$	45,673			$	342		$	49,978

The amortized cost of Level 3 securities was $50,701,000 at March 31, 2013 with an unrealized loss of $723,000. The securities in this category are generally equity investments, municipal securities with no readily determinable fair value or failed auction rate securities. Management evaluated the fair value of these securities based on an evaluation of the underlying issuer, prevailing rates and market liquidity.

Fair_Values_of_Financial_Instr

Fair Values of Financial Instruments	3 Months Ended
Fair Values of Financial Instruments	Mar. 31, 2014
Text Block [Abstract]	'
Fair Values of Financial Instruments	'
	Note 11. Fair Values of Financial Instruments
	The following methods and assumptions were used by the Company in estimating fair values of its financial instruments. Excluded from this disclosure are all nonfinancial instruments. Accordingly, the aggregate fair value amounts presented do not represent the underlying value of the Company.
	The assumptions used below are expected to approximate those that market participants would use in valuing these financial instruments.
	Fair value estimates are made at a specific point in time, based on available market information and judgments about the financial instrument, including estimates of timing, amount of expected future cash flows and the credit standing of the issuer. Such estimates do not consider the tax impact of the realization of unrealized gains or losses. In some cases, the fair value estimates cannot be substantiated by comparison to independent markets. In addition, the disclosed fair value may not be realized in the immediate settlement of the financial instrument. Care should be exercised in deriving conclusions about our business, its value or financial position based on the fair value information of financial instruments presented below.
	Securities held-to-maturity: The fair values of these securities were based on quoted market prices, where available, as provided by third-party investment portfolio pricing vendors. If quoted market prices were not available, fair values provided by the vendors were based on quoted market prices of comparable instruments in active markets and/or based on a matrix pricing methodology which employs The Bond Market Association’s standard calculations for cash flow and price/yield analysis, live benchmark bond pricing and terms/condition data available from major pricing sources. Management regards the inputs and methods used by third party pricing vendors to be “Level 2 inputs and methods” as defined in the “fair value hierarchy” provided by FASB.
	Loans: For variable-rate loans, that reprice frequently and with no significant change in credit risk, fair values are based on carrying amounts. The fair value of other loans is estimated using discounted cash flow analysis, based on interest rates currently being offered for loans with similar terms to borrowers of similar credit quality. Incremental credit risk for nonperforming loans has been considered.
	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.
	Other borrowed funds: The fair value of other borrowed funds is based on the discounted value of contractual cash flows. The discount rate used is estimated based on the rates currently offered for other borrowed funds of similar remaining maturities.
	Subordinated debentures: The fair value of subordinated debentures is based on the discounted value of contractual cash flows. The discount rate used is estimated based on the rates currently offered for other subordinated debentures of similar remaining maturities.
	The following presents (in thousands) the carrying amount, estimated fair value, and placement in the fair value hierarchy of the Company’s financial instruments as of March 31, 2014 and December 31, 2013. This table excludes financial instruments for which the carrying amount approximates fair value. Financial assets for which the fair value approximates carrying value include cash and cash equivalents, short-term investments, FHLBB stock and accrued interest receivable. Financial liabilities for which the fair value approximates carrying value include non-maturity deposits, short-
	term borrowings and accrued interest payable.


							Fair Value Measurements
			Carrying Amount		Estimated Fair		Level 1 Inputs		Level 2 Inputs		Level 3 Inputs
			Carrying Amount		Value		Level 1 Inputs		Level 2 Inputs		Level 3 Inputs
	(in thousands)
	March 31, 2014
	Financial assets:
	Securities held-to-maturity		$	1,478,450	$	1,468,731	$	—	$	1,468,731	$	—
	Loans (1)			1,242,802		1,219,892		—		—		1,219,892
	Financial liabilities:
	Time deposits			381,199		386,274		—		386,274		—
	Other borrowed funds			272,644		272,343		—		272,343		—
	Subordinated debentures			36,083		40,427		—		—		40,427

	December 31, 2013
	Financial assets:
	Securities held-to-maturity			1,487,884		1,464,449		—		1,464,449		—
	Loans (1)			1,243,822		1,214,192		—		—		1,214,192
	Financial liabilities:
	Time deposits			382,224		386,742		—		386,742		—
	Other borrowed funds			255,144		254,736		—		254,736		—
	Subordinated debentures			36,083		39,503		—		—		39,503

	-1	Comprised of loans (including collateral dependent impaired loans), net of deferred loan costs and the allowance for loan losses.

Recent_Accounting_Developments

Recent Accounting Developments	3 Months Ended
Recent Accounting Developments	Mar. 31, 2014
Accounting Changes And Error Corrections [Abstract]	'
Recent Accounting Developments	'
	Note 12. Recent Accounting Developments
	In December 2011, the FASB issued ASU 2011-11, Balance Sheet (Topic 210), Disclosures about offsetting assets and liabilities. ASU 2011-11 requires an entity to disclose information about offsetting and related arrangements to enable users of financial statements to understand the effect of those arrangements on its financial position, and to allow investors to better compare financial statements prepared under U.S. GAAP with financial statements prepared under IFRS. The new standards are effective for annual periods beginning January 1, 2013, and interim periods within those annual periods. Retrospective application is required. The Company implemented the provisions of ASU 2011-11 as of January 1, 2013. The adoption of this pronouncement did not have a material effect on the consolidated financial statements.
	In February 2013, the FASB issued ASU 2013-02, Comprehensive Income (Topic 220) Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income. ASU 2013-02 requires an entity to report the effect of significant reclassifications out of accumulated other comprehensive income on the respective line items in net income or as a separate disclosure in the notes to the financial statements. The new standard is effective for annual periods beginning January 1, 2013, and interim periods within those annual periods. The Company has presented a separate footnote (Note 7) as a result of this pronouncement.
	In January 2014, the FASB issued ASU 2014-04, Receivables-Troubled Debt Restructurings by Creditors (Subtopic 310-40) Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure. The amendments in this update clarify that an in substance repossession or foreclosure occurs, and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan, upon either (1) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or (2) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. The amendments in this update are effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2014. The Company has assessed the impact of ASU 2014-14 and the adoption of this amendment will not have a material impact on the Company’s financial statements.

Fair_Value_Measurements_Polici

Fair Value Measurements (Policies)	3 Months Ended
Fair Value Measurements (Policies)	Mar. 31, 2014
Accounting Changes And Error Corrections [Abstract]	'
Fair Value Measurements and Disclosures	'
	The Company follows FASB ASC 820-10, Fair Value Measurements and Disclosures, (formerly SFAS 157, “Fair Value Measurements,”) which among other things, requires enhanced disclosures about assets and liabilities carried at fair value. ASC 820-10 establishes a hierarchal disclosure framework associated with the level of pricing observability utilized in measuring financial instruments at fair value. The three broad levels of the hierarchy are as follows:
	Level I – Quoted prices are available in active markets for identical assets or liabilities as of the reported date. The type of financial instruments included in Level I are highly liquid cash instruments with quoted prices such as G-7 government, agency securities, listed equities and money market securities, as well as listed derivative instruments.
	Level II – Pricing inputs are other than quoted prices in active markets, which are either directly or indirectly observable as of the reported date. The nature of these financial instruments include cash instruments for which quoted prices are available but traded less frequently, derivative instruments whose fair value have been derived using a model where inputs to the model are directly observable in the market, or can be derived principally from or corroborated by observable market data, and instruments that are fair valued using other financial instruments, the parameters of which can be directly observed. Instruments which are generally included in this category are corporate bonds and loans, mortgage whole loans, municipal bonds and OTC derivatives.

	Level III – Instruments that have little to no pricing observability as of the reported date. These financial instruments do not have two-way markets and are measured using management’s best estimate of fair value, where the inputs into the determination of fair value require significant management judgment or estimation. Instruments that are included in this category generally include certain commercial mortgage loans, certain private equity investments, distressed debt, non-investment grade residual interests in securitizations, as well as certain highly structured OTC derivative contracts.
Disclosures about Offsetting Assets and Liabilities	'
Disclosures about Offsetting Assets and Liabilities	In December 2011, the FASB issued ASU 2011-11, Balance Sheet (Topic 210), Disclosures about offsetting assets and liabilities. ASU 2011-11 requires an entity to disclose information about offsetting and related arrangements to enable users of financial statements to understand the effect of those arrangements on its financial position, and to allow investors to better compare financial statements prepared under U.S. GAAP with financial statements prepared under IFRS. The new standards are effective for annual periods beginning January 1, 2013, and interim periods within those annual periods. Retrospective application is required. The Company implemented the provisions of ASU 2011-11 as of January 1, 2013. The adoption of this pronouncement did not have a material effect on the consolidated financial statements.
Comprehensive Income	'
Comprehensive Income	In February 2013, the FASB issued ASU 2013-02, Comprehensive Income (Topic 220) Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income. ASU 2013-02 requires an entity to report the effect of significant reclassifications out of accumulated other comprehensive income on the respective line items in net income or as a separate disclosure in the notes to the financial statements. The new standard is effective for annual periods beginning January 1, 2013, and interim periods within those annual periods. The Company has presented a separate footnote (Note 7) as a result of this pronouncement.
Debt Restructuring	'
Debt Restructuring	In January 2014, the FASB issued ASU 2014-04, Receivables-Troubled Debt Restructurings by Creditors (Subtopic 310-40) Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure. The amendments in this update clarify that an in substance repossession or foreclosure occurs, and a creditor is considered to have received physical possession of residential real estate property collateralizing a consumer mortgage loan, upon either (1) the creditor obtaining legal title to the residential real estate property upon completion of a foreclosure or (2) the borrower conveying all interest in the residential real estate property to the creditor to satisfy that loan through completion of a deed in lieu of foreclosure or through a similar legal agreement. The amendments in this update are effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2014. The Company has assessed the impact of ASU 2014-14 and the adoption of this amendment will not have a material impact on the Company’s financial statements.

Stock_Option_Accounting_Tables

Stock Option Accounting (Tables)	3 Months Ended
Stock Option Accounting (Tables)	Mar. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Summary of Stock Option Activity under Stock Option Plan	'
	Stock option activity under the Company’s stock option plan for the three months ended March 31, 2014 is as follows:


		Amount			Weighted
					Average
					Exercise Price
	Shares under option:
	Outstanding at beginning of year		20,375		$	31.82
	Exercised		(75	)		31.83
	Forfeited		—			—

	Outstanding at end of period		20,300		$	31.82

	Exercisable at end of period		20,300		$	31.82

	Available to be granted at end of period		224,884

Securities_AvailableforSale_Ta

Securities Available-for-Sale (Tables)	3 Months Ended
Securities Available-for-Sale (Tables)	Mar. 31, 2014
Text Block [Abstract]	'
Summary of Securities Available-for-Sale	'

		March 31, 2014								December 31, 2013
		Amortized		Gross		Gross		Fair		Amortized		Gross		Gross		Fair
		Cost		Unrealized		Unrealized		Value		Cost		Unrealized		Unrealized		Value
				Gains		Losses						Gains		Losses
		( In thousands)
	U.S. Treasury	$	1,998	$	2	$	—	$	2,000	$	1,997	$	1	$	—	$	1,998
	U.S. Government Sponsored Enterprises		—		—		—		—		9,995		9		—		10,004
	Small Business Administration		7,109		40		—		7,149		7,270		32		—		7,302
	U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities		426,521		825		1,331		426,015		404,103		588		1,501		403,190
	Privately Issued Residential Mortgage Backed Securities		2,189		18		20		2,187		2,294		6		23		2,277
	Obligations Issued by States and Political Subdivisions		34,063		8		870		33,201		37,578		15		870		36,723

	Other Debt Securities		2,300		—		120		2,180		2,300		—		125		2,175
	Equity Securities		406		164		—		570		406		170		—		576


	Total	$	474,586	$	1,057	$	2,341	$	473,302	$	465,943	$	821	$	2,519	$	464,245

Maturity Distribution of Securities Available-for-Sale	'
	The following table shows the maturity distribution of the Company’s securities available-for-sale at March 31, 2014.


		Amortized		Fair
		Cost		Value
		( In thousands)
	Within one year	$	29,408	$	29,429
	After one but within five years		193,847		193,971
	After five but within ten years		230,394		229,759
	More than 10 years		19,031		18,193
	Non-maturing		1,906		1,950

	Total	$	474,586	$	473,302

Continuous Unrealized Loss Position for 12 Months or Less and 12 Months or Longer	'
	The following table shows the temporarily impaired securities of the Company’s available-for-sale portfolio at March 31, 2014. This table shows the unrealized market loss of securities that have been in a continuous unrealized loss position for 12 months or less and a continuous loss position for 12 months and longer. There are 32 and 10 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 240 holdings at March 31, 2014.


		March 31, 2014
		Less than 12 months				12 months or longer				Total
	Temporarily Impaired Investments	Fair Value		Unrealized		Fair Value		Unrealized		Fair Value		Unrealized
	Temporarily Impaired Investments	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
		(In thousands)
	U.S. Government Sponsored Enterprises	$	—	$	—	$	—	$	—	$	—	$	—
	U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities		208,531		980		56,658		351		265,189		1,331
	Privately Issued Residential Mortgage Backed Securities		800		20		—		—		800		20
	Obligations Issued by States and Political Subdivisions		—		—		3,820		870		3,820		870
	Other Debt Securities		—		—		1,380		120		1,380		120

	Total temporarily impaired securities	$	209,331	$	1,000	$	61,858	$	1,341	$	271,189	$	2,341

	The following table shows the temporarily impaired securities of the Company’s available-for-sale portfolio at December 31, 2013. This table shows the unrealized market loss of securities that have been in a continuous unrealized loss position for 12 months or less and a continuous loss position for 12 months and longer. There are 20 and 7 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 458 holdings at December 31, 2013.


		December 31, 2013
		Less than 12 months				12 months or longer				Total
	Temporarily Impaired Investments	Fair Value		Unrealized		Fair Value		Unrealized		Fair Value		Unrealized
	Temporarily Impaired Investments	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
		(In thousands)
	U.S. Government Sponsored Enterprises	$	—	$	—	$	—	$	—	$	—	$	—
	U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities		289,709		1, 352		24,557		149		314,266		1,501
	Privately Issued Residential Mortgage Backed Securities		1,486		23		—		—		1,486		23
	Obligations Issued by States and Political Subdivisions		—		—		3,820		870		3,820		870
	Other Debt Securities		—		—		1,376		125		1,376		125

	Total temporarily impaired securities	$	291,195	$	1,375	$	29,753	$	1,144	$	320,948	$	2,519

Investment_Securities_HeldtoMa1

Investment Securities Held-to-Maturity (Tables)	3 Months Ended
Investment Securities Held-to-Maturity (Tables)	Mar. 31, 2014
Text Block [Abstract]	'
Unrealized Gain (Losses) on Securities	'

		March 31, 2014								December 31, 2013
		Amortized		Gross		Gross		Estimated		Amortized		Gross		Gross		Estimated
		Cost		Unrealized		Unrealized		Fair		Cost		Unrealized		Unrealized		Fair
				Gains		Losses		Value				Gains		Losses		Value
		(In thousands)
	U.S. Government Sponsored Enterprises	$	292,325	$	512	$	1,653	$	291,184	$	291,779	$	185	$	5,043	$	286,921
	U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities		1,186,125		4,949		13,527		1,177,547		1,196,105		2,239		20,816		1,177,528

	Total	$	1,478,450	$	5,461	$	15,180	$	1,468,731	$	1,487,884	$	2,424	$	25,859	$	1,464,449

Company's Securities Held-to-Maturity	'
	The following table shows the maturity distribution of the Company’s securities held-to-maturity at March 31, 2014.


		Amortized		Fair
		Cost		Value
		( In thousands)
	Within one year	$	4,830	$	4,849
	After one but within five years		845,948		842,706
	After five but within ten years		626,601		620,086
	More than ten years		1,071		1 ,090

	Total	$	1,478,450	$	1,468,731

Unrealized Market Loss of Securities	'
	The following table shows the temporarily impaired securities of the Company’s held-to-maturity portfolio at March 31, 2014. This table shows the unrealized market loss of securities that have been in a continuous unrealized loss position for 12 months or less and a continuous loss position for 12 months and longer. There are 134 and 21 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 303 holdings at March 31, 2014.


		March 31, 2014
		Less Than 12 Months				12 Months or Longer				Total
	Temporarily Impaired Investments	Fair Value		Unrealized		Fair Value		Unrealized		Fair Value		Unrealized
	Temporarily Impaired Investments	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
		(Dollars in thousands)
	U.S. Government Sponsored Enterprises	$	164,174	$	1,653	$	—	$	—	$	164,174	$	1,653
	U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities		607,346		10,558		129,838		2,969		737,184		13,527

	Total temporarily impaired securities	$	771,520	$	12,211	$	129,838	$	2,969	$	901,358	$	15,180

	The following table shows the temporarily impaired securities of the Company’s held-to-maturity portfolio at December 31, 2013. This table shows the unrealized market loss of securities that have been in a continuous unrealized loss position for 12 months or less and a continuous loss position for 12 months and longer. There are 3 and 1 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 96 holdings at December 31, 2013.


		December 31, 2013
		Less Than 12 Months				12 Months or Longer				Total
	Temporarily Impaired Investments	Fair Value		Unrealized		Fair Value		Unrealized		Fair Value		Unrealized
	Temporarily Impaired Investments	Fair Value		Losses		Fair Value		Losses		Fair Value		Losses
		( In thousands)
	U.S. Government Sponsored Enterprises	$	232,535	$	5,043	$	—	$	—	$	232,535	$	5,043
	U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities		931,180		18,654		80,362		2,162		1,011,542		20,816

	Total temporarily impaired securities	$	1,163,715	$	23,697	$	80,362	$	2,162	$	1,244,077	$	25,859

Allowance_for_Loan_Losses_Tabl

Allowance for Loan Losses (Tables)	3 Months Ended
Allowance for Loan Losses (Tables)	Mar. 31, 2014
Receivables [Abstract]	'
Summary of Changes in Allowance for Loan Losses	'
	The following table summarizes the changes in the Company’s allowance for loan losses for the periods indicated.


			Three months ended
			March 31,
			2014				2013
			(in thousands)
	Allowance for loan losses, beginning of period		$	20,941			$	19,197
	Loans charged off			(429	)			(371	)
	Recoveries on loans previously charged-off			147				183

	Net charge-offs			(282	)			(188	)
	Provision charged to expense			600				750

	Allowance for loan losses, end of period		$	21,259			$	19,759

Summary of Allowance for Loan Losses	'
	Further information pertaining to the allowance for loan losses for the three months ending March 31, 2014 follows:


			Construction				Commercial				Commercial				Residential				Consumer			Home			Unallocated		Total
			and Land				and				Real				Real							Equity
			Development				Industrial				Estate				Estate
			(Dollars in thousands)
	Allowance for loan losses:
	Balance at December 31, 2013		$	2,174			$	2,989			$	11,218			$	2,006			$	432		$	959		$	1,163	$	20,941
	Charge-offs			(250	)			—				—				—				(179	)		—			—		(429	)
	Recoveries			—				24				1				5				116			1			—		147
	Provision			(99	)			77				655				(138	)			56			(58	)		107		600

	Ending balance at March 31, 2014		$	1,825			$	3,090			$	11,874			$	1,873			$	425		$	902		$	1,270	$	21,259

	Amount of allowance for loan losses for loans deemed to be impaired		$	25			$	358			$	382			$	122			$	—		$	94		$	—		981

	Amount of allowance for loan losses for loans not deemed to be impaired		$	1,800			$	2,732			$	11,492			$	1,751			$	425		$	808		$	1,270	$	20,278


	Loans:
	Ending balance		$	25,928			$	95,775			$	708,551			$	290,465			$	9,542		$	133,800		$	—	$	1,264,061

	Loans deemed to be impaired		$	358			$	1,129			$	4,408			$	998			$	—		$	94		$	—	$	6,987

	Loans not deemed to be impaired		$	25,570			$	94,646			$	704,143			$	289,467			$	9,542		$	133,706		$	—	$	1,257,074

	Further information pertaining to the allowance for loan losses for three months ending March 31, 2013 follows:


			Construction				Commercial				Commercial				Residential				Consumer			Home			Unallocated		Total
			and Land				and				Real				Real							Equity
			Development				Industrial				Estate				Estate
			(Dollars in thousands)
	Allowance for loan losses:

	Balance at December 31, 2012		$	3,041			$	3,118			$	9,065			$	1,994			$	333		$	886		$	760	$	19,197
	Charge-offs			—				(226	)			—				—				(145	)		—			—		(371	)
	Recoveries			—				65				2				2				114						—		183
	Provision			158				566				(288	)			75				55			(53	)		237		750

	Ending balance at March 31, 2013		$	3,199			$	3,523			$	8,779			$	2,071			$	357		$	833		$	997	$	19,759

	Amount of allowance for loan losses for loans deemed to be impaired		$	1,000			$	103			$	396			$	155			$	—		$	96		$	—		1,750

	Amount of allowance for loan losses for loans not deemed to be impaired		$	2,199			$	3,420			$	8,383			$	1,916			$	357		$	737		$	997	$	18,009

	Loans:
	Ending balance		$	34,021			$	110,537			$	570,441			$	292,871			$	7,910		$	121,989		$	—	$	1,137,769

	Loans deemed to be impaired		$	1,500			$	1,396			$	2,262			$	1,232			$	—		$	96		$	—	$	6,486

	Loans not deemed to be impaired		$	32,521			$	109,141			$	568,179			$	291,639			$	7,910		$	121,893		$	—	$	1,131,283

Loans by Risk Rating	'
	The following table presents the Company’s loans by risk rating at March 31, 2014.


			Construction				Commercial				Commercial
			and land				and				real
			development				industrial				estate
			(Dollars in thousands)
	Grade:
	1-3 (Pass)		$	18,303			$	93,485			$	699,238
	4 (Monitor)			7,267				1,120				4,905
	5 (Substandard)			—				—				—
	6 (Doubtful)			—				—				—
	Impaired			358				1,170				4,408

	Total		$	25,928			$	95,775			$	708,551

	The following table presents the Company’s loans by risk rating at December 31, 2013.


			Construction				Commercial				Commercial
			and land				and				real
			development				industrial				estate
			(Dollars in thousands)
	Grade:
	1-3(Pass)		$	25,138			$	90,563			$	707,461
	4 (Monitor)			7,312				472				1,346
	5 (Substandard)			—				—				—
	6 (Doubtful)			—				—				—
	Impaired			608				1,367				4,520

	Total		$	33,058			$	92,402			$	713,327

Aging of Past Due Loan Losses	'
	Further information pertaining to the allowance for loan losses at March 31, 2014 follows:


			Accruing				Non Accrual				Accrual				Total				Current Loans			Total
			30-89 Days								Greater				Past Due
			Past Due								Than
											90 Days
			(Dollars in thousands)
	Construction and land development		$	—			$	358			$	—			$	358			$	25,570		$	25,928
	Commercial and industrial			467				475				—				942				94,833			95,775
	Commercial real estate			2,633				218				—				2,851				705,700			708,551
	Residential real estate			229				464				—				693				289,772			290,465
	Consumer and overdrafts			1				5				—				6				9,536			9,542
	Home equity			470				40				—				510				133,290			133,800

	Total		$	3,800			$	1,560			$	—			$	5,360			$	1,258,701		$	1,264,061

	Further information pertaining to the allowance for loan losses at December 31, 2013 follows:


			Accruing				Non Accrual				Accrual				Total				Current Loans			Total
			30-89 Days								Greater				Past Due
			Past Due								Than
											90 Days
			(Dollars in thousands)
	Construction and land development		$	—			$	500			$	—			$	500			$	32,558		$	33,058
	Commercial and industrial			112				706								818				91,584			92,402
	Commercial real estate			1,496				306				—				1,802				711,525			713,327
	Residential real estate			2,232				1,034				—				3,266				282,775			286,041
	Consumer and overdrafts			11				3				—				14				9,644			9,658
	Home equity			1,710				—				—				1,710				128,567			130,277

	Total		$	5,561			$	2,549			$	—			$	8,110			$	1,256,653		$	1,264,763

Information Pertaining to Impaired Loans	'
	The following is information pertaining to impaired loans for March 31, 2014:


			Carrying Value				Unpaid				Required				Average				Interest
							Principal				Reserve				Carrying Value				Income
							Balance												Recognized
			(Dollars in thousands)
	With no required reserve recorded:
	Construction and land development		$	250			$	3,292			$	—			$	437			$	—
	Commercial and industrial			11				42				—				116				—
	Commercial real estate			55				56				—				41				—
	Residential real estate			—				—				—				164				—
	Consumer			—				—				—				—				—
	Home equity			—				—				—				—				—

	Total		$	316			$	3 390			$	—				758			$	—

	With required reserve recorded:
	Construction and land development		$	108			$	108			$	25				108			$	—
	Commercial and industrial			1,118				1,352				358				1,116				8
	Commercial real estate			4,353				4,442				382				4,420				32
	Residential real estate			998				1,082				122				949				1
	Consumer			—				—				—				—				—
	Home equity			94				94				94				94				—

	Total		$	6,671			$	7,078			$	981			$	6,687			$	41

	Total:
	Construction and land development		$	358			$	3,400			$	25				545			$	—
	Commercial and industrial			1,129				1,394				358				1,232				8
	Commercial real estate			4,408				4,498				382				4,461				32
	Residential real estate			998				1,082				122				1,113				1
	Consumer			—				—				—				—				—
	Home equity			94				94				94				94				—

	Total		$	6,987			$	10,468			$	981			$	7,445			$	41

	The following is information pertaining to impaired loans for March 31, 2013:


			Carrying Value				Unpaid				Required				Average				Interest
							Principal				Reserve				Carrying Value				Income
							Balance												Recognized
			(Dollars in thousands)
	With no required reserve recorded:
	Construction and land development		$	—			$	—			$	—			$	—			$	—
	Commercial and industrial			566				1,058				—				545				—
	Commercial real estate			165				198				—				167				—
	Residential real estate			319				321				—				102				—
	Consumer			—				—				—				—				—
	Home equity			—				—				—				—				—

	Total		$	1,050			$	1,577			$	—			$	814			$	—

	With required reserve recorded:
	Construction and land development		$	1,500			$	3,292			$	1,000			$	1,500			$	—
	Commercial and industrial			830				1,046				103				840				9
	Commercial real estate			2,097				2,146				396				2,105				24
	Residential real estate			913				995				155				779				—
	Consumer			—				—				—				—				—
	Home equity			96				96				96				96				—

	Total		$	5,436			$	7,575			$	1,750			$	5,320			$	33

Total:
Construction and land development		$	1,500			$	3,292			$	1,000			$	1,500			$	—
Commercial and industrial			1,396				2,104				103				1,385				9
Commercial real estate			2,262				2,344				396				2,272				24
Residential real estate			1,232				1,316				155				881				—
Consumer			—				—				—				—				—
Home equity			96				96				96				96				—

Total		$	6,486			$	9,152			$	1,750			$	6,134			$	33

Reclassifications_Out_of_Accum1

Reclassifications Out of Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2014
Text Block [Abstract]	'
Reclassifications Out of Accumulated Other Comprehensive Income	'
	Amount Reclassified from Accumulated
	Other Comprehensive Income


	Details about Accumulated		Three Months Ended			Three Months Ended			Affected Line Item
	Other Comprehensive		March 31, 2014			March 31, 2013			in the Statement
	Income Components								Where Net Income
									is Presented
	(in thousands)
	Unrealized gains and losses on available-for-sale securities

			$	—		$	883		Net gains on sales of investments
				—			(350	)	Provision for income taxes

			$	—		$	533		Net income


	Accretion of unrealized losses transferred

			$	1,507		$	—		Securities held-to-maturity
				(583	)		—		Provision for income taxes

			$	924		$	—		Net income


	Amortization of defined benefit pension items

	Prior-service costs		$	(3	)(b)	$	(3	)	Salaries and employee benefits
	Actuarial gains (losses)			(92	)(b)		(287	)	Salaries and employee benefits

	Total before tax			(95	)		(290	)	Income before taxes
	Tax (expense) or benefit			38			117		Provision for income taxes

	Net of tax		$	(57	)	$	(173	)	Net income


	Total reclassifications for the period		$	867		$	360		Net income, net of tax


	(a)	Amounts in parentheses indicate debits to profit/loss.
	(b)	These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see employee benefits footnote (Note 9) for additional details).

Earnings_Per_Share_EPS_Tables

Earnings Per Share ("EPS") (Tables)	3 Months Ended
Earnings Per Share ("EPS") (Tables)	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Reconciliation of Basic EPS and Diluted EPS	'
	The following table is a reconciliation of basic EPS and diluted EPS for the three months ended March 31,


		2014		2013
	Basic EPS Computation:
	(in thousands except share and per share data)
	Numerator:
	Net income, Class A	$	3,867	$	3,502
	Net income, Class B		1,065		974
	Denominator:
	Weighted average shares outstanding, Class A		3,582,421		3,569,546
	Weighted average shares outstanding, Class B		1,974,180		1,986,880
	Basic EPS, Class A	$	1.08	$	0.98
	Basic EPS, Class B		0.54		0.49

	Diluted EPS Computation:
	Numerator:
	Net income, Class A	$	3,867	$	3,502
	Net income, Class B		1,065		974

	Total net income, for diluted EPS, Class A computation		4,932		4,476
	Denominator:
	Weighted average shares outstanding, basic, Class A		3,582,421		3,569,546
	Weighted average shares outstanding, Class B		1,974,180		1,986,880
	Dilutive effect of Class A stock options		1,576		939

	Weighted average shares outstanding diluted, Class A		5,558,177		5,557,365
	Weighted average shares outstanding, Class B		1,974,180		1,986,880
	Diluted EPS, Class A	$	0.89	$	0.81
	Diluted EPS, Class B		0.54		0.49

Employee_Benefits_Tables

Employee Benefits (Tables)	3 Months Ended
Employee Benefits (Tables)	Mar. 31, 2014
Compensation And Retirement Disclosure [Abstract]	'
Components of Net Periodic Benefit Cost (Credit)	'
	Components of Net Periodic Benefit Cost (Credit) for the Three Months Ended March 31,


		Pension Benefits						Supplemental Insurance/
		Pension Benefits						Retirement Plan
		2014			2013			2014		2013
		(In thousands)
	Service cost	$	258		$	299		$	389	$	381
	Interest		367			314			331		267
	Expected return on plan assets		(636	)		(470	)		—		—
	Recognized prior service cost (benefit)		(26	)		(26	)		29		29
	Recognized net actuarial losses		3			158			88		129

	Net periodic benefit (credit)cost	$	(34	)	$	275		$	837	$	806

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
Fair Value Measurements (Tables)	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Financial Instruments Measured at Fair Value on a Recurring and Non-recurring Basis	'
	The results of the fair value hierarchy as of March 31, 2014, are as follows:


	Financial Instruments Measured at Fair Value on a Recurring Basis:
			Securities AFS Fair Value Measurements Using
			Carrying		Quoted Prices			Significant		Significant
			Value		In Active			Observable		Other
					Markets for			Inputs		Unobservable
					Identical			(Level 2)		Inputs
					Assets					(Level 3)
					(Level 1)
			(In thousands)
	U.S. Treasury		$	2,000	$	—		$	2,000	$	—

	U.S. Government Sponsored Enterprises			—		—			—		—

	SBA Backed Securities			7,149		—			7,149		—
	U.S. Government Agency and Sponsored Mortgage Backed Securities			426,015		—			426,015		—

	Privately Issued Residential Mortgage Backed Securities			2,187		—			2,187		—

	Obligations Issued by States and Political Subdivisions			33,201		—			411		32,790

	Other Debt Securities			2,180		—			2,180		—
	Equity Securities			570		280			—		290

	Total		$	473,302	$	280		$	439,942	$	33,080


	Financial Instruments Measured at Fair Value on a Non-recurring Basis:

	Impaired Loans			1,833		—			—		1,833
Assets Measured at Fair Value	'
	The following table presents additional information about assets measured at fair value on a recurring and nonrecurring basis for which the Company has utilized Level 3 inputs to determine fair value (dollars in thousands). Management continues to monitor the assumptions used to value the assets listed below.


	Asset		Fair Value		Valuation Technique		Unobservable Input	Unobservable Input
	Asset		Fair Value		Valuation Technique		Unobservable Input	Value or Range
	Securities AFS(4)		$	33,080	Discounted cash flow		Discount rate	0% -1% (3)
	Impaired Loans			1,833	Appraisal of collateral (1)		Appraisal adjustments (2)	0%-25% discount

	-1	Fair value is generally determined through independent appraisals of the underlying collateral, which generally include various Level 3 inputs which are not identifiable.
	-2	Appraisals may be adjusted by management for qualitative factors such as economic conditions and estimated expenses.
	-3	Weighted averages
	-4	Municipal securities generally have maturities of one year or less and, therefore, the amortized cost equates to the fair value.
Changes in Level 3 Securities	'
	The changes in Level 3 securities for the three-month period ended March 31, 2014 are shown in the table below:


			Auction Rate		Obligations			Equity		Total
			Securities		Issued by States			Securities
					& Political
					Subdivisions
			(In thousands)
	Balance at December 31, 2013		$	3,820	$	32,487		$	290	$	36,597
	Purchases			—		7,205			—		7,205
	Maturities and calls			—		(10,717	)		—		(10,717	)
	Amortization			—		(5	)		—		(5	)
	Changes in fair value			—		—			—		—

	Balance at March 31, 2014		$	3,820	$	28,970		$	290	$	33,080

	The changes in Level 3 securities for the three-month period ended March 31, 2013, are shown in the table below:


			Auction Rate		Obligations			Equity		Total
			Securities		Issued by States			Securities
					& Political
					Subdivisions
			(In thousands)
	Balance at December 31, 2012		$	3,963	$	49,477		$	342	$	53,782
	Purchases			—		6,179			—		6,179
	Maturities and calls			—		(9,974	)		—		(9,974	)
	Amortization			—		(9	)		—		(9	)
	Changes in fair value			—		—			—		—

	Balance at March 31, 2013		$	3,963	$	45,673		$	342	$	49,978

Fair_Values_of_Financial_Instr1

Fair Values of Financial Instruments (Tables)	3 Months Ended
Fair Values of Financial Instruments (Tables)	Mar. 31, 2014
Text Block [Abstract]	'
Carrying Amount and Fair Value of Company's Financial Instruments	'
	The following presents (in thousands) the carrying amount, estimated fair value, and placement in the fair value hierarchy of the Company’s financial instruments as of March 31, 2014 and December 31, 2013. This table excludes financial instruments for which the carrying amount approximates fair value. Financial assets for which the fair value approximates carrying value include cash and cash equivalents, short-term investments, FHLBB stock and accrued interest receivable. Financial liabilities for which the fair value approximates carrying value include non-maturity deposits, short-
	term borrowings and accrued interest payable.


							Fair Value Measurements
			Carrying Amount		Estimated Fair		Level 1 Inputs		Level 2 Inputs		Level 3 Inputs
			Carrying Amount		Value		Level 1 Inputs		Level 2 Inputs		Level 3 Inputs
	(in thousands)
	March 31, 2014
	Financial assets:
	Securities held-to-maturity		$	1,478,450	$	1,468,731	$	—	$	1,468,731	$	—
	Loans (1)			1,242,802		1,219,892		—		—		1,219,892
	Financial liabilities:
	Time deposits			381,199		386,274		—		386,274		—
	Other borrowed funds			272,644		272,343		—		272,343		—
	Subordinated debentures			36,083		40,427		—		—		40,427

	December 31, 2013
	Financial assets:
	Securities held-to-maturity			1,487,884		1,464,449		—		1,464,449		—
	Loans (1)			1,243,822		1,214,192		—		—		1,214,192
	Financial liabilities:
	Time deposits			382,224		386,742		—		386,742		—
	Other borrowed funds			255,144		254,736		—		254,736		—
	Subordinated debentures			36,083		39,503		—		—		39,503

	-1	Comprised of loans (including collateral dependent impaired loans), net of deferred loan costs and the allowance for loan losses.

Basis_of_Financial_Statement_P1

Basis of Financial Statement Presentation - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2014
	Segment
Accounting Policies [Abstract]	'
Equity ownership interest	100.00%
Number of reportable segments	1

Recent_Market_Developments_Add

Recent Market Developments - Additional Information (Detail) (USD $)	0 Months Ended	3 Months Ended
	Nov. 02, 2009	Mar. 31, 2014	Jun. 30, 2013
Recent Market Development [Line Items]	'	'	'
FDIC deposit insurance amount	'	$250,000	'
Uniform increase in assessment rates effective on January 1, 2011	0.03%	'	'
Refund amount received by company	'	'	$2,400,000
Common equity Tier 1 ratio as percentage of risk-weighted assets	'	4.50%	'
Minimum Tier 1 capital ratio as percentage of risk-weighted assets	'	4.00%	'
Revised minimum Tier 1 capital ratio as percentage of risk-weighted assets	'	6.00%	'
Tier 1 capital conservation buffer as percentage of risk-weighted assets	'	2.50%	'
Minimum [Member]	'	'	'
Recent Market Development [Line Items]	'	'	'
Restoration period	'7 years	'	'
Maximum [Member]	'	'	'
Recent Market Development [Line Items]	'	'	'
Restoration period	'8 years	'	'

Stock_Option_Accounting_Summar

Stock Option Accounting - Summary of Stock Option Activity under Stock Option Plan (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Shares under option:	'	'
Outstanding at beginning of year, Amount	20,375	'
Exercised, Amount	-75	-1,600
Forfeited, Amount	'	'
Outstanding at end of period, Amount	20,300	'
Exercisable at end of period, Amount	20,300	'
Available to be granted at end of period, Amount	224,884	'
Outstanding at beginning of year, Weighted Average Exercise Price	$31.82	'
Exercised, Weighted Average Exercise Price	$31.83	'
Forfeited, Weighted Average Exercise Price	'	'
Outstanding at end of period, Weighted Average Exercise Price	$31.82	'
Exercisable at end of period, Weighted Average Exercise Price	$31.82	'

Stock_Option_Accounting_Additi

Stock Option Accounting - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Number of outstanding options	20,300	20,375
Weighted average exercise price	$31.82	$31.82
Options granted	0	'
Class A Common Stock [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Number of outstanding options	20,300	'
Exercise prices of shares outstanding, minimum	$31.60	'
Exercise prices of shares outstanding, maximum	$31.83	'
Weighted average exercise price	$31.82	'
Weighted average remaining contractual life	'6 months	'
Intrinsic value of options exercisable	$46,284	'
Intrinsic value of options exercised	$171	'

Securities_AvailableforSale_Su

Securities Available-for-Sale - Summary of Securities Available-for-Sale (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	$474,586	$465,943
Gross Unrealized Gains	1,057	821
Gross Unrealized Losses	2,341	2,519
Total, Fair Value	473,302	464,245
U.S. Treasury [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	1,998	1,997
Gross Unrealized Gains	2	1
Gross Unrealized Losses	'	'
Total, Fair Value	2,000	1,998
U.S. Government Sponsored Enterprises [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	'	9,995
Gross Unrealized Gains	'	9
Gross Unrealized Losses	'	'
Total, Fair Value	'	10,004
SBA Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	7,109	7,270
Gross Unrealized Gains	40	32
Gross Unrealized Losses	'	'
Total, Fair Value	7,149	7,302
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	426,521	404,103
Gross Unrealized Gains	825	588
Gross Unrealized Losses	1,331	1,501
Total, Fair Value	426,015	403,190
Privately Issued Residential Mortgage Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	2,189	2,294
Gross Unrealized Gains	18	6
Gross Unrealized Losses	20	23
Total, Fair Value	2,187	2,277
Obligations Issued by States and Political Subdivisions [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	34,063	37,578
Gross Unrealized Gains	8	15
Gross Unrealized Losses	870	870
Total, Fair Value	33,201	36,723
Other Debt Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	2,300	2,300
Gross Unrealized Gains	'	'
Gross Unrealized Losses	120	125
Total, Fair Value	2,180	2,175
Equity Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	406	406
Gross Unrealized Gains	164	170
Gross Unrealized Losses	'	'
Total, Fair Value	$570	$576

Securities_AvailableforSale_Ad

Securities Available-for-Sale - Additional Information (Detail) (USD $)	3 Months Ended							3 Months Ended
	Mar. 31, 2014	Sep. 30, 2013	Mar. 31, 2013	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014	Dec. 31, 2013
				Securities AFS [Member]	Securities AFS [Member]	U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]	U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]	Federal Home Loan Bank of Boston [Member]	Federal Home Loan Bank of Boston [Member]
				Security	Security
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'	'	'	'	'	'
Securities available-for-sale with an amortized cost	'	$1,012,370,000	'	'	'	'	'	'	'
Securities held-to-maturity at their fair value	'	987,037,000	'	'	'	'	'	'	'
Securities at fair value pledged to secure public deposits and repurchase agreements	'	'	'	'	'	357,512,000	368,137,000	'	'
Securities available-for-sale are securities pledged for borrowing	'	'	'	'	'	'	'	30,744,000	12,214,000
Realized gains on sales of investments	'	'	'	'	'	'	'	0	'
Realized gross gain	'	'	883,000	'	'	'	'	'	'
Proceeds from sales of securities available-for-sale	'	'	$87,570,000	'	'	'	'	'	'
Weighted average remaining life of investment securities available-for-sale	'5 years 1 month 6 days	'	'	'	'	'	'	'	'
Number of securities, temporarily impaired for less than 12 months	'	'	'	32	20	'	'	'	'
Number of securities, temporarily impaired for 12 months or longer	'	'	'	10	7	'	'	'	'
Number of securities, temporarily impaired, total	'	'	'	240	458	'	'	'	'

Securities_AvailableforSale_Ma

Securities Available-for-Sale - Maturity Distribution of Securities Available-for-Sale (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Investments Debt And Equity Securities [Abstract]	'	'
Within one year, Amortized Cost	$29,408	'
After one but within five years, Amortized Cost	193,847	'
After five but within ten years, Amortized Cost	230,394	'
More than 10 years, Amortized Cost	19,031	'
Non-maturing, Amortized Cost	1,906	'
Total, Amortized Cost	474,586	'
Within one year, Fair Value	29,429	'
After one but within five years, Fair Value	193,971	'
After five but within ten years, Fair Value	229,759	'
More than 10 years, Fair Value	18,193	'
Non-maturing, Fair Value	1,950	'
Total, Fair Value	$473,302	$464,245

Securities_AvailableforSale_Co

Securities Available-for-Sale - Continuous Unrealized Loss Position for 12 Months or Less and 12 Months or Longer (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than 12 months, Fair Value	$209,331	$291,195
Less than 12 months, Unrealized Losses	1,000	1,375
12 months or longer, Fair Value	61,858	29,753
12 months or longer, Unrealized Losses	1,341	1,144
Total, Fair Value	271,189	320,948
Total, Unrealized Losses	2,341	2,519
U.S. Government Sponsored Enterprises [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than 12 months, Fair Value	'	'
Less than 12 months, Unrealized Losses	'	'
12 months or longer, Fair Value	'	'
12 months or longer, Unrealized Losses	'	'
Total, Fair Value	'	'
Total, Unrealized Losses	'	'
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than 12 months, Fair Value	208,531	289,709
Less than 12 months, Unrealized Losses	980	1,352
12 months or longer, Fair Value	56,658	24,557
12 months or longer, Unrealized Losses	351	149
Total, Fair Value	265,189	314,266
Total, Unrealized Losses	1,331	1,501
Privately Issued Residential Mortgage Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than 12 months, Fair Value	800	1,486
Less than 12 months, Unrealized Losses	20	23
12 months or longer, Fair Value	'	'
12 months or longer, Unrealized Losses	'	'
Total, Fair Value	800	1,486
Total, Unrealized Losses	20	23
Obligations Issued by States and Political Subdivisions [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than 12 months, Fair Value	'	'
Less than 12 months, Unrealized Losses	'	'
12 months or longer, Fair Value	3,820	3,820
12 months or longer, Unrealized Losses	870	870
Total, Fair Value	3,820	3,820
Total, Unrealized Losses	870	870
Other Debt Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than 12 months, Fair Value	'	'
Less than 12 months, Unrealized Losses	'	'
12 months or longer, Fair Value	1,380	1,376
12 months or longer, Unrealized Losses	120	125
Total, Fair Value	1,380	1,376
Total, Unrealized Losses	$120	$125

Investment_Securities_HeldtoMa2

Investment Securities Held-to-Maturity - Unrealized Gain (Losses) on Securities (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	$1,478,450	$1,487,884
Gross Unrealized Gains	5,461	2,424
Gross Unrealized Losses	15,180	25,859
Estimated Fair Value	1,468,731	1,464,449
U.S. Government Sponsored Enterprises [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	292,325	291,779
Gross Unrealized Gains	512	185
Gross Unrealized Losses	1,653	5,043
Estimated Fair Value	291,184	286,921
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	1,186,125	1,196,105
Gross Unrealized Gains	4,949	2,239
Gross Unrealized Losses	13,527	20,816
Estimated Fair Value	$1,177,547	$1,177,528

Investment_Securities_HeldtoMa3

Investment Securities Held-to-Maturity - Additional Information (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Schedule of Held-to-maturity Securities [Line Items]	'	'
Securities pledged for borrowing at the Federal Home Loan Bank of Boston	$1,468,731,000	$1,464,449,000
Weighted average remaining life of investment securities held-to-maturity	'5 years	'
Held-to-Maturity Securities [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Number of securities, temporarily impaired for less than 12 months	134	3
Number of securities, temporarily impaired for 12 months or longer	21	1
Number of securities, temporarily impaired, total	303	96
U.S. Government Sponsored Enterprises [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Securities at fair value pledged to secure public deposits and repurchase agreements	751,754,000	732,144,000
Securities pledged for borrowing at the Federal Home Loan Bank of Boston	291,184,000	286,921,000
Weighted average remaining life	224,667,000	'
Federal Home Loan Bank of Boston [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Securities pledged for borrowing at the Federal Home Loan Bank of Boston	$514,421,000	$510,060,000

Investment_Securities_HeldtoMa4

Investment Securities Held-to-Maturity - Company's Securities Held-to-Maturity (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Investments Debt And Equity Securities [Abstract]	'	'
Within one year, Amortized Cost	$4,830	'
After one but within five years, Amortized Cost	845,948	'
After five but within ten years, Amortized Cost	626,601	'
More than ten years, Amortized Cost	1,071	'
Total, Amortized Cost	1,478,450	1,487,884
Within one year, Fair Value	4,849	'
After one but within five years, Fair Value	842,706	'
After five but within ten years, Fair Value	620,086	'
More than ten years, Fair Value	1,090	'
Estimated Fair Value	$1,468,731	$1,464,449

Investment_Securities_HeldtoMa5

Investment Securities Held-to-Maturity - Unrealized Market Loss of Securities (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Held-to-maturity Securities [Line Items]	'	'
Less Than 12 Months, Fair Value	$771,520	$1,163,715
Less Than 12 Months, Unrealized Losses	12,211	23,697
12 Months or Longer, Fair Value	129,838	80,362
12 Months or Longer, Unrealized Losses	2,969	2,162
Total, Fair Value	901,358	1,244,077
Total, Unrealized Losses	15,180	25,859
U.S. Government Sponsored Enterprises [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Less Than 12 Months, Fair Value	164,174	232,535
Less Than 12 Months, Unrealized Losses	1,653	5,043
12 Months or Longer, Fair Value	'	'
12 Months or Longer, Unrealized Losses	'	'
Total, Fair Value	164,174	232,535
Total, Unrealized Losses	1,653	5,043
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Less Than 12 Months, Fair Value	607,346	931,180
Less Than 12 Months, Unrealized Losses	10,558	18,654
12 Months or Longer, Fair Value	129,838	80,362
12 Months or Longer, Unrealized Losses	2,969	2,162
Total, Fair Value	737,184	1,011,542
Total, Unrealized Losses	$13,527	$20,816

Allowance_for_Loan_Losses_Summ

Allowance for Loan Losses - Summary of Changes in Allowance for Loan Losses (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Receivables [Abstract]	'	'
Allowance for loan losses, beginning of period	$20,941	$19,197
Loans charged off	-429	-371
Recoveries on loans previously charged-off	147	183
Net charge-offs	-282	-188
Provision charged to expense	600	750
Allowance for loan losses, end of period	$21,259	$19,759

Allowance_for_Loan_Losses_Summ1

Allowance for Loan Losses - Summary of Allowance for Loan Losses (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Allowance for loan losses:	'	'	'
Allowance for loan losses, beginning of period	$20,941	$19,197	'
Charge-offs	-429	-371	'
Recoveries	147	183	'
Provision	600	750	'
Allowance for loan losses, end of period	21,259	19,759	'
Amount of allowance for loan losses for loans deemed to be impaired	981	1,750	'
Amount of allowance for loan losses for loans not deemed to be impaired	20,278	18,009	'
Loans:	'	'	'
Total loans, net	1,264,061	1,137,769	1,264,763
Loans deemed to be impaired	6,987	6,486	'
Loans not deemed to be impaired	1,257,074	1,131,283	'
Construction and Land Development [Member]	'	'	'
Allowance for loan losses:	'	'	'
Allowance for loan losses, beginning of period	2,174	3,041	'
Charge-offs	-250	'	'
Recoveries	'	'	'
Provision	-99	158	'
Allowance for loan losses, end of period	1,825	3,199	'
Amount of allowance for loan losses for loans deemed to be impaired	25	1,000	'
Amount of allowance for loan losses for loans not deemed to be impaired	1,800	2,199	'
Loans:	'	'	'
Total loans, net	25,928	34,021	33,058
Loans deemed to be impaired	358	1,500	'
Loans not deemed to be impaired	25,570	32,521	'
Commercial and Industrial [Member]	'	'	'
Allowance for loan losses:	'	'	'
Allowance for loan losses, beginning of period	2,989	3,118	'
Charge-offs	'	-226	'
Recoveries	24	65	'
Provision	77	566	'
Allowance for loan losses, end of period	3,090	3,523	'
Amount of allowance for loan losses for loans deemed to be impaired	358	103	'
Amount of allowance for loan losses for loans not deemed to be impaired	2,732	3,420	'
Loans:	'	'	'
Total loans, net	95,775	110,537	92,402
Loans deemed to be impaired	1,129	1,396	'
Loans not deemed to be impaired	94,646	109,141	'
Commercial Real Estate [Member]	'	'	'
Allowance for loan losses:	'	'	'
Allowance for loan losses, beginning of period	11,218	9,065	'
Charge-offs	'	'	'
Recoveries	1	2	'
Provision	655	-288	'
Allowance for loan losses, end of period	11,874	8,779	'
Amount of allowance for loan losses for loans deemed to be impaired	382	396	'
Amount of allowance for loan losses for loans not deemed to be impaired	11,492	8,383	'
Loans:	'	'	'
Total loans, net	708,551	570,441	713,327
Loans deemed to be impaired	4,408	2,262	'
Loans not deemed to be impaired	704,143	568,179	'
Residential Real Estate [Member]	'	'	'
Allowance for loan losses:	'	'	'
Allowance for loan losses, beginning of period	2,006	1,994	'
Charge-offs	'	'	'
Recoveries	5	2	'
Provision	-138	75	'
Allowance for loan losses, end of period	1,873	2,071	'
Amount of allowance for loan losses for loans deemed to be impaired	122	155	'
Amount of allowance for loan losses for loans not deemed to be impaired	1,751	1,916	'
Loans:	'	'	'
Total loans, net	290,465	292,871	286,041
Loans deemed to be impaired	998	1,232	'
Loans not deemed to be impaired	289,467	291,639	'
Consumer [Member]	'	'	'
Allowance for loan losses:	'	'	'
Allowance for loan losses, beginning of period	432	333	'
Charge-offs	-179	-145	'
Recoveries	116	114	'
Provision	56	55	'
Allowance for loan losses, end of period	425	357	'
Amount of allowance for loan losses for loans deemed to be impaired	'	'	'
Amount of allowance for loan losses for loans not deemed to be impaired	425	357	'
Loans:	'	'	'
Total loans, net	9,542	7,910	9,658
Loans deemed to be impaired	'	'	'
Loans not deemed to be impaired	9,542	7,910	'
Home Equity [Member]	'	'	'
Allowance for loan losses:	'	'	'
Allowance for loan losses, beginning of period	959	886	'
Charge-offs	'	'	'
Recoveries	1	'	'
Provision	-58	-53	'
Allowance for loan losses, end of period	902	833	'
Amount of allowance for loan losses for loans deemed to be impaired	94	96	'
Amount of allowance for loan losses for loans not deemed to be impaired	808	737	'
Loans:	'	'	'
Total loans, net	133,800	121,989	130,277
Loans deemed to be impaired	94	96	'
Loans not deemed to be impaired	133,706	121,893	'
Unallocated [Member]	'	'	'
Allowance for loan losses:	'	'	'
Allowance for loan losses, beginning of period	1,163	760	'
Charge-offs	'	'	'
Recoveries	'	'	'
Provision	107	237	'
Allowance for loan losses, end of period	1,270	997	'
Amount of allowance for loan losses for loans deemed to be impaired	'	'	'
Amount of allowance for loan losses for loans not deemed to be impaired	1,270	997	'
Loans:	'	'	'
Total loans, net	'	'	'
Loans deemed to be impaired	'	'	'
Loans not deemed to be impaired	'	'	'

Allowance_for_Loan_Losses_Loan

Allowance for Loan Losses - Loans by Risk Rating (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Loans by risk rating	'	'	'
Financing Receivable, Net	$1,264,061	$1,264,763	$1,137,769
Construction and Land Development [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	25,928	33,058	34,021
Construction and Land Development [Member] \| 1-3 (Pass) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	18,303	25,138	'
Construction and Land Development [Member] \| 4 (Monitor) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	7,267	7,312	'
Construction and Land Development [Member] \| 5 (Substandard) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	'	'	'
Construction and Land Development [Member] \| 6 (Doubtful) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	'	'	'
Construction and Land Development [Member] \| Impaired [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	358	608	'
Commercial and Industrial [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	95,775	92,402	110,537
Commercial and Industrial [Member] \| 1-3 (Pass) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	93,485	90,563	'
Commercial and Industrial [Member] \| 4 (Monitor) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	1,120	472	'
Commercial and Industrial [Member] \| 5 (Substandard) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	'	'	'
Commercial and Industrial [Member] \| 6 (Doubtful) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	'	'	'
Commercial and Industrial [Member] \| Impaired [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	1,170	1,367	'
Commercial Real Estate [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	708,551	713,327	570,441
Commercial Real Estate [Member] \| 1-3 (Pass) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	699,238	707,461	'
Commercial Real Estate [Member] \| 4 (Monitor) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	4,905	1,346	'
Commercial Real Estate [Member] \| 5 (Substandard) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	'	'	'
Commercial Real Estate [Member] \| 6 (Doubtful) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	'	'	'
Commercial Real Estate [Member] \| Impaired [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	$4,408	$4,520	'

Allowance_for_Loan_Losses_Agin

Allowance for Loan Losses - Aging of Past Due Loan Losses (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Accruing 30-89 Days Past Due	$3,800	$5,561	'
Non Accrual	1,560	2,549	'
Accrual Greater Than 90 Days	'	'	'
Total Past Due	5,360	8,110	'
Current Loans	1,258,701	1,256,653	'
Total loans, net	1,264,061	1,264,763	1,137,769
Construction and Land Development [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Accruing 30-89 Days Past Due	'	'	'
Non Accrual	358	500	'
Accrual Greater Than 90 Days	'	'	'
Total Past Due	358	500	'
Current Loans	25,570	32,558	'
Total loans, net	25,928	33,058	34,021
Commercial and Industrial [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Accruing 30-89 Days Past Due	467	112	'
Non Accrual	475	706	'
Accrual Greater Than 90 Days	'	'	'
Total Past Due	942	818	'
Current Loans	94,833	91,584	'
Total loans, net	95,775	92,402	110,537
Commercial Real Estate [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Accruing 30-89 Days Past Due	2,633	1,496	'
Non Accrual	218	306	'
Accrual Greater Than 90 Days	'	'	'
Total Past Due	2,851	1,802	'
Current Loans	705,700	711,525	'
Total loans, net	708,551	713,327	570,441
Residential Real Estate [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Accruing 30-89 Days Past Due	229	2,232	'
Non Accrual	464	1,034	'
Accrual Greater Than 90 Days	'	'	'
Total Past Due	693	3,266	'
Current Loans	289,772	282,775	'
Total loans, net	290,465	286,041	292,871
Consumer [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Accruing 30-89 Days Past Due	1	11	'
Non Accrual	5	3	'
Accrual Greater Than 90 Days	'	'	'
Total Past Due	6	14	'
Current Loans	9,536	9,644	'
Total loans, net	9,542	9,658	7,910
Home Equity [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Accruing 30-89 Days Past Due	470	1,710	'
Non Accrual	40	'	'
Accrual Greater Than 90 Days	'	'	'
Total Past Due	510	1,710	'
Current Loans	133,290	128,567	'
Total loans, net	$133,800	$130,277	$121,989

Allowance_for_Loan_Losses_Info

Allowance for Loan Losses - Information Pertaining to Impaired Loans (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'
With no required reserve recorded, Carrying Value	$316	$1,050
With no required reserve recorded, Unpaid Balance Principal	'	1,577
With no required reserve recorded, Required Reserve	'	'
With no required reserve recorded, Average Carrying Value	758	814
With no required reserve recorded, Interest Income Recognized	'	'
With required reserve recorded, Carrying Value	6,671	5,436
With required reserve recorded, Unpaid Balance Principal	7,078	7,575
With required reserve recorded, Required Reserve	981	1,750
With required reserve recorded, Average Carrying Value	6,687	5,320
With required reserve recorded, Interest Income Recognized	41	33
Carrying Value	6,987	6,486
Unpaid Principal Balance	10,468	9,152
With required reserve recorded, Required Reserve	981	1,750
Average Carrying Value	7,445	6,134
Interest Income Recognized	41	33
Construction and Land Development [Member]	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'
With no required reserve recorded, Carrying Value	250	'
With no required reserve recorded, Unpaid Balance Principal	3,292	'
With no required reserve recorded, Required Reserve	'	'
With no required reserve recorded, Average Carrying Value	437	'
With no required reserve recorded, Interest Income Recognized	'	'
With required reserve recorded, Carrying Value	108	1,500
With required reserve recorded, Unpaid Balance Principal	108	3,292
With required reserve recorded, Required Reserve	25	1,000
With required reserve recorded, Average Carrying Value	108	1,500
With required reserve recorded, Interest Income Recognized	'	'
Carrying Value	358	1,500
Unpaid Principal Balance	3,400	3,292
With required reserve recorded, Required Reserve	25	1,000
Average Carrying Value	545	1,500
Interest Income Recognized	'	'
Commercial and Industrial [Member]	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'
With no required reserve recorded, Carrying Value	11	566
With no required reserve recorded, Unpaid Balance Principal	42	1,058
With no required reserve recorded, Required Reserve	'	'
With no required reserve recorded, Average Carrying Value	116	545
With no required reserve recorded, Interest Income Recognized	'	'
With required reserve recorded, Carrying Value	1,118	830
With required reserve recorded, Unpaid Balance Principal	1,352	1,046
With required reserve recorded, Required Reserve	358	103
With required reserve recorded, Average Carrying Value	1,116	840
With required reserve recorded, Interest Income Recognized	8	9
Carrying Value	1,129	1,396
Unpaid Principal Balance	1,394	2,104
With required reserve recorded, Required Reserve	358	103
Average Carrying Value	1,232	1,385
Interest Income Recognized	8	9
Commercial Real Estate [Member]	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'
With no required reserve recorded, Carrying Value	55	165
With no required reserve recorded, Unpaid Balance Principal	56	198
With no required reserve recorded, Required Reserve	'	'
With no required reserve recorded, Average Carrying Value	41	167
With no required reserve recorded, Interest Income Recognized	'	'
With required reserve recorded, Carrying Value	4,353	2,097
With required reserve recorded, Unpaid Balance Principal	4,442	2,146
With required reserve recorded, Required Reserve	382	396
With required reserve recorded, Average Carrying Value	4,420	2,105
With required reserve recorded, Interest Income Recognized	32	24
Carrying Value	4,408	2,262
Unpaid Principal Balance	4,498	2,344
With required reserve recorded, Required Reserve	382	396
Average Carrying Value	4,461	2,272
Interest Income Recognized	32	24
Residential Real Estate [Member]	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'
With no required reserve recorded, Carrying Value	'	319
With no required reserve recorded, Unpaid Balance Principal	'	321
With no required reserve recorded, Required Reserve	'	'
With no required reserve recorded, Average Carrying Value	164	102
With no required reserve recorded, Interest Income Recognized	'	'
With required reserve recorded, Carrying Value	998	913
With required reserve recorded, Unpaid Balance Principal	1,082	995
With required reserve recorded, Required Reserve	122	155
With required reserve recorded, Average Carrying Value	949	779
With required reserve recorded, Interest Income Recognized	1	'
Carrying Value	998	1,232
Unpaid Principal Balance	1,082	1,316
With required reserve recorded, Required Reserve	122	155
Average Carrying Value	1,113	881
Interest Income Recognized	1	'
Consumer [Member]	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'
With no required reserve recorded, Carrying Value	'	'
With no required reserve recorded, Unpaid Balance Principal	'	'
With no required reserve recorded, Required Reserve	'	'
With no required reserve recorded, Average Carrying Value	'	'
With no required reserve recorded, Interest Income Recognized	'	'
With required reserve recorded, Carrying Value	'	'
With required reserve recorded, Unpaid Balance Principal	'	'
With required reserve recorded, Required Reserve	'	'
With required reserve recorded, Average Carrying Value	'	'
With required reserve recorded, Interest Income Recognized	'	'
Carrying Value	'	'
Unpaid Principal Balance	'	'
With required reserve recorded, Required Reserve	'	'
Average Carrying Value	'	'
Interest Income Recognized	'	'
Home Equity [Member]	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'
With no required reserve recorded, Carrying Value	'	'
With no required reserve recorded, Unpaid Balance Principal	'	'
With no required reserve recorded, Required Reserve	'	'
With no required reserve recorded, Average Carrying Value	'	'
With no required reserve recorded, Interest Income Recognized	'	'
With required reserve recorded, Carrying Value	94	96
With required reserve recorded, Unpaid Balance Principal	94	96
With required reserve recorded, Required Reserve	94	96
With required reserve recorded, Average Carrying Value	94	96
With required reserve recorded, Interest Income Recognized	'	'
Carrying Value	94	96
Unpaid Principal Balance	94	96
With required reserve recorded, Required Reserve	94	96
Average Carrying Value	94	96
Interest Income Recognized	'	'

Allowance_for_Loan_Losses_Addi

Allowance for Loan Losses - Additional Information (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Receivables [Abstract]	'	'
Troubled debt restructurings, subsequently defaulted	$0	$0

Reclassifications_Out_of_Accum2

Reclassifications Out of Accumulated Other Comprehensive Income - Reclassifications Out of Accumulated Other Comprehensive Income (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Net gains on sales of investments	'	$883
Securities held-to-maturity	7,780	1,520
Provision for income taxes	-293	-288
Net income	4,932	4,476
Salaries and employee benefits	-8,875	-8,618
Reclassification Out of Accumulated Other Comprehensive Income [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Net income	867	360
Reclassification Out of Accumulated Other Comprehensive Income [Member] \| Unrealized Gains and Losses on Available-for-Sale Securities [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Net gains on sales of investments	'	883
Provision for income taxes	'	-350
Net income	'	533
Reclassification Out of Accumulated Other Comprehensive Income [Member] \| Accretion of Unrealized Losses Transferred [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Securities held-to-maturity	1,507	'
Provision for income taxes	-583	'
Net income	924	'
Reclassification Out of Accumulated Other Comprehensive Income [Member] \| Prior-Service Costs [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Salaries and employee benefits	-3	-3
Reclassification Out of Accumulated Other Comprehensive Income [Member] \| Actuarial Gains (Losses) [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Salaries and employee benefits	-92	-287
Reclassification Out of Accumulated Other Comprehensive Income [Member] \| Amortization of Defined Benefit Pension Items [Member]	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'
Income before taxes	-95	-290
Provision for income taxes	38	117
Net income	($57)	($173)

Earnings_Per_Share_EPS_Additio

Earnings Per Share ("EPS") - Additional Information (Detail) (Class A Common Stock [Member])	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]	'	'
Dilutive effect of stock options, increment in shares	1,576	939
Minimum [Member]	'	'
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]	'	'
Percentage of dividends paid	200.00%	'

Earnings_Per_Share_EPS_Reconci

Earnings Per Share ("EPS") - Reconciliation of Basic EPS and Diluted EPS (Detail) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]	'	'
Net income	$4,932	$4,476
Class A Common Stock [Member]	'	'
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]	'	'
Net income	3,867	3,502
Weighted average shares outstanding, basic	3,582,421	3,569,546
Basic earnings per share	$1.08	$0.98
Dilutive effect of Class A stock options	1,576	939
Weighted average shares outstanding, diluted	5,558,177	5,557,365
Diluted earnings per share	$0.89	$0.81
Class B Common Stock [Member]	'	'
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]	'	'
Net income	$1,065	$974
Weighted average shares outstanding, basic	1,974,180	1,986,880
Basic earnings per share	$0.54	$0.49
Weighted average shares outstanding, diluted	1,974,180	1,986,880
Diluted earnings per share	$0.54	$0.49

Employee_Benefits_Additional_I

Employee Benefits - Additional Information (Detail) (USD $)	3 Months Ended
Employee Benefits - Additional Information (Detail) (USD $)	Mar. 31, 2014
Compensation And Retirement Disclosure [Abstract]	'
Number of years service to participate in supplemental plan	'1 year
Expected contribution to pension plan in current fiscal year	$1,000,000
Current fiscal year contribution to pension plan	460,000
Expected contribution to pension plan in remainder of current fiscal year	$540,000

Employee_Benefits_Components_o

Employee Benefits - Components of Net Periodic Benefit Cost (Credit) (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Pension Benefits [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Service cost	$258	$299
Interest	367	314
Expected return on plan assets	-636	-470
Recognized prior service cost (benefit)	-26	-26
Recognized net actuarial losses	3	158
Net periodic benefit (credit) cost	-34	275
Supplemental Insurance/ Retirement Plan [Member]	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'
Service cost	389	381
Interest	331	267
Expected return on plan assets	'	'
Recognized prior service cost (benefit)	29	29
Recognized net actuarial losses	88	129
Net periodic benefit (credit) cost	$837	$806

Fair_Value_Measurements_Financ

Fair Value Measurements - Financial Instruments Measured at Fair Value on a Recurring and Non-recurring Basis (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	$473,302	$464,245
Fair Value Measurements, Level 1 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	280	'
Fair Value Measurements, Level 2 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	439,942	'
Fair Value Measurements, Level 3 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	33,080	'
U.S. Treasury [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	2,000	1,998
U.S. Treasury [Member] \| Fair Value Measurements, Level 1 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
U.S. Treasury [Member] \| Fair Value Measurements, Level 2 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	2,000	'
U.S. Treasury [Member] \| Fair Value Measurements, Level 3 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
U.S. Government Sponsored Enterprises [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	10,004
U.S. Government Sponsored Enterprises [Member] \| Fair Value Measurements, Level 1 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
U.S. Government Sponsored Enterprises [Member] \| Fair Value Measurements, Level 2 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
U.S. Government Sponsored Enterprises [Member] \| Fair Value Measurements, Level 3 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
SBA Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	7,149	7,302
SBA Backed Securities [Member] \| Fair Value Measurements, Level 1 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
SBA Backed Securities [Member] \| Fair Value Measurements, Level 2 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	7,149	'
SBA Backed Securities [Member] \| Fair Value Measurements, Level 3 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	426,015	403,190
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member] \| Fair Value Measurements, Level 1 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member] \| Fair Value Measurements, Level 2 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	426,015	'
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member] \| Fair Value Measurements, Level 3 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
Privately Issued Residential Mortgage Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	2,187	2,277
Privately Issued Residential Mortgage Backed Securities [Member] \| Fair Value Measurements, Level 1 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
Privately Issued Residential Mortgage Backed Securities [Member] \| Fair Value Measurements, Level 2 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	2,187	'
Privately Issued Residential Mortgage Backed Securities [Member] \| Fair Value Measurements, Level 3 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
Obligations Issued by States and Political Subdivisions [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	33,201	36,723
Obligations Issued by States and Political Subdivisions [Member] \| Fair Value Measurements, Level 1 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
Obligations Issued by States and Political Subdivisions [Member] \| Fair Value Measurements, Level 2 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	411	'
Obligations Issued by States and Political Subdivisions [Member] \| Fair Value Measurements, Level 3 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	32,790	'
Other Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	2,180	2,175
Other Debt Securities [Member] \| Fair Value Measurements, Level 1 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
Other Debt Securities [Member] \| Fair Value Measurements, Level 2 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	2,180	'
Other Debt Securities [Member] \| Fair Value Measurements, Level 3 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
Equity Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	570	576
Equity Securities [Member] \| Fair Value Measurements, Level 1 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	280	'
Equity Securities [Member] \| Fair Value Measurements, Level 2 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
Equity Securities [Member] \| Fair Value Measurements, Level 3 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	290	'
Impaired Loans [Member] \| Fair Value Measurements, Level 1 Inputs [Member]	'	'
Financial Instruments Measured at Fair Value on a Non-recurring Basis	'	'
Impaired Loans	'	'
Impaired Loans [Member] \| Fair Value Measurements, Level 2 Inputs [Member]	'	'
Financial Instruments Measured at Fair Value on a Non-recurring Basis	'	'
Impaired Loans	'	'
Impaired Loans [Member] \| Fair Value Measurements, Level 3 Inputs [Member]	'	'
Financial Instruments Measured at Fair Value on a Non-recurring Basis	'	'
Impaired Loans	1,833	'
Carrying Value [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	473,302	'
Carrying Value [Member] \| U.S. Treasury [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	2,000	'
Carrying Value [Member] \| U.S. Government Sponsored Enterprises [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	'	'
Carrying Value [Member] \| SBA Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	7,149	'
Carrying Value [Member] \| U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	426,015	'
Carrying Value [Member] \| Privately Issued Residential Mortgage Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	2,187	'
Carrying Value [Member] \| Obligations Issued by States and Political Subdivisions [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	33,201	'
Carrying Value [Member] \| Other Debt Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	2,180	'
Carrying Value [Member] \| Equity Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	570	'
Carrying Value [Member] \| Impaired Loans [Member]	'	'
Financial Instruments Measured at Fair Value on a Non-recurring Basis	'	'
Impaired Loans	$1,833	'

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2014	Mar. 31, 2013
	Mar. 31, 2014	Fair Value Measurements, Level 3 Inputs [Member]	Fair Value Measurements, Level 3 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'	'
Specific adjustments to impaired loans recognized	$254,000	'	'
Transfers between level 1 and 2	0	'	'
Liabilities measured at fair value on a recurring or nonrecurring basis	0	'	'
Amortized cost of Level 3 securities	'	33,951,000	50,701,000
Unrealized loss	'	$870,000	$723,000

Fair_Value_Measurements_Assets

Fair Value Measurements - Assets Measured at Fair Value (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014
Securities AFS [Member]	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'
Fair Value	$33,080
Valuation Technique	'Discounted cash flow
Unobservable Input	'Discount rate
Impaired Loans [Member]	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'
Fair Value	$1,833
Valuation Technique	'Appraisal of collateral
Unobservable Input	'Appraisal adjustments
Minimum [Member] \| Securities AFS [Member]	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'
Unobservable Input Value or Range	0.00%
Minimum [Member] \| Impaired Loans [Member]	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'
Unobservable Input Value or Range	0.00%
Maximum [Member] \| Securities AFS [Member]	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'
Unobservable Input Value or Range	1.00%
Maximum [Member] \| Impaired Loans [Member]	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'
Unobservable Input Value or Range	25.00%

Fair_Value_Measurements_Change

Fair Value Measurements - Changes in Level 3 Securities (Detail) (USD $)	3 Months Ended					3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2012
	Mar. 31, 2014	Mar. 31, 2013	Auction Rate Securities [Member]	Auction Rate Securities [Member]	Auction Rate Securities [Member]	Obligations Issued by States and Political Subdivisions [Member]	Obligations Issued by States and Political Subdivisions [Member]	Equity Securities [Member]	Equity Securities [Member]	Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'	'	'	'	'	'	'	'	'	'
Beginning Balance	$36,597	$53,782	$3,820	$3,963	$3,963	$32,487	$49,477	$290	$342	$342
Purchases	7,205	6,179	'	'	'	7,205	6,179	'	'	'
Maturities and calls	-10,717	-9,974	'	'	'	-10,717	-9,974	'	'	'
Amortization	-5	-9	'	'	'	-5	-9	'	'	'
Changes in fair value	'	'	'	'	'	'	'	'	'	'
Ending Balance	$33,080	$49,978	$3,820	$3,963	$3,963	$28,970	$45,673	$290	$342	$342

Fair_Values_of_Financial_Instr2

Fair Values of Financial Instruments - Carrying Amount and Fair Value of Company's Financial Instruments (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Financial assets:	'	'
Securities held-to-maturity	$1,478,450	$1,487,884
Loans	1,242,802	1,243,822
Financial liabilities:	'	'
Time deposits	381,199	382,224
Other borrowed funds	272,644	255,144
Subordinated debentures	36,083	36,083
Carrying Value [Member]	'	'
Financial assets:	'	'
Securities held-to-maturity	1,478,450	1,487,884
Loans	1,242,802	1,243,822
Financial liabilities:	'	'
Time deposits	381,199	382,224
Other borrowed funds	272,644	255,144
Subordinated debentures	36,083	36,083
Estimated Fair Value [Member]	'	'
Financial assets:	'	'
Securities held-to-maturity	1,468,731	1,464,449
Loans	1,219,892	1,214,192
Financial liabilities:	'	'
Time deposits	386,274	386,742
Other borrowed funds	272,343	254,736
Subordinated debentures	40,427	39,503
Fair Value Measurements, Level 1 Inputs [Member]	'	'
Financial assets:	'	'
Securities held-to-maturity	'	'
Loans	'	'
Financial liabilities:	'	'
Time deposits	'	'
Other borrowed funds	'	'
Subordinated debentures	'	'
Fair Value Measurements, Level 2 Inputs [Member]	'	'
Financial assets:	'	'
Securities held-to-maturity	1,468,731	1,464,449
Loans	'	'
Financial liabilities:	'	'
Time deposits	386,274	386,742
Other borrowed funds	272,343	254,736
Subordinated debentures	'	'
Fair Value Measurements, Level 3 Inputs [Member]	'	'
Financial assets:	'	'
Securities held-to-maturity	'	'
Loans	1,219,892	1,214,192
Financial liabilities:	'	'
Time deposits	'	'
Other borrowed funds	'	'
Subordinated debentures	$40,427	$39,503