Century Bancorp (CNBKA) 10-Q7 Aug 142014 Q2 Quarterly reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Jun. 30, 2014	Jul. 31, 2014	Jul. 31, 2014
	Jun. 30, 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	30-Jun-14	'	'
Document Fiscal Year Focus	'2014	'	'
Document Fiscal Period Focus	'Q2	'	'
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	'	3,590,429	1,967,580

Consolidated_Balance_Sheets_un

Consolidated Balance Sheets (unaudited) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Assets	'	'
Cash and due from banks	$77,565	$59,956
Federal funds sold and interest-bearing deposits in other banks	14,212	34,722
Total cash and cash equivalents	91,777	94,678
Short-term investments	2,125	4,617
Securities available-for-sale, amortized cost $495,162 and $465,943, respectively	494,309	464,245
Securities held-to-maturity, fair value $1,537,839 and $1,464,449, respectively	1,536,988	1,487,884
Federal Home Loan Bank of Boston stock, at cost	19,656	18,072
Loans, net:	'	'
Commercial and industrial	88,666	92,402
Construction and land development	25,861	33,058
Commercial real estate	766,965	713,327
Residential real estate	282,468	286,041
Home equity	140,616	130,277
Consumer and other	9,649	9,658
Total loans, net	1,314,225	1,264,763
Less: allowance for loan losses	21,722	20,941
Net loans	1,292,503	1,243,822
Bank premises and equipment	23,456	23,400
Accrued interest receivable	6,714	6,539
Goodwill	2,714	2,714
Other assets	87,392	85,183
Total assets	3,557,634	3,431,154
Deposits:	'	'
Demand deposits	504,265	475,862
Savings and NOW deposits	1,045,987	992,796
Money Market Accounts	911,897	864,957
Time deposits	388,189	382,224
Total deposits	2,850,338	2,715,839
Securities sold under agreements to repurchase	180,010	214,440
Other borrowed funds	267,500	255,144
Subordinated debentures	36,083	36,083
Due to broker	2,000	'
Other liabilities	33,442	33,176
Total liabilities	3,369,373	3,254,682
Stockholders' Equity	'	'
Preferred stock - $1.00 par value; 100,000 shares authorized; no shares issued and outstanding	0	0
Additional paid-in capital	11,935	11,932
Retained earnings	190,182	180,747
Stockholders' equity before adjustment of accumulated other comprehensive income (loss)	207,674	198,235
Unrealized losses on securities available-for-sale, net of taxes	-540	-1,045
Unrealized losses on securities transferred to held-to-maturity, net of taxes	-11,935	-13,667
Pension liability, net of taxes	-6,938	-7,051
Total accumulated other comprehensive loss, net of taxes	-19,413	-21,763
Total stockholders' equity	188,261	176,472
Total liabilities and stockholders' equity	3,557,634	3,431,154
Class A Common Stock [Member]	'	'
Stockholders' Equity	'	'
Common stock value	3,589	3,580
Total stockholders' equity	3,589	3,580
Class B Common Stock [Member]	'	'
Stockholders' Equity	'	'
Common stock value	1,968	1,976
Total stockholders' equity	$1,968	$1,976

Consolidated_Balance_Sheets_un1

Consolidated Balance Sheets (unaudited) (Parenthetical) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Amortized cost	$495,162	$465,943
Held-to-maturity securities, fair value	$1,537,839	$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	3,589,129	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	1,967,580	1,976,180

Consolidated_Statements_of_Inc

Consolidated Statements of Income (unaudited) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Interest income	'	'	'	'
Loans	$12,611	$11,997	$25,060	$23,878
Securities held-to-maturity	8,020	1,419	15,800	2,939
Securities available-for-sale	794	5,571	1,614	11,188
Federal funds sold and interest-bearing deposits in other banks	129	145	211	264
Total interest income	21,554	19,132	42,685	38,269
Interest expense	'	'	'	'
Savings and NOW deposits	660	649	1,269	1,259
Money market accounts	669	582	1,308	1,114
Time deposits	1,141	1,234	2,226	2,568
Securities sold under agreements to repurchase	93	89	194	179
Other borrowed funds and subordinated debentures	2,237	2,066	4,420	4,092
Total interest expense	4,800	4,620	9,417	9,212
Net interest income	16,754	14,512	33,268	29,057
Provision for loan losses	450	750	1,050	1,500
Net interest income after provision for loan losses	16,304	13,762	32,218	27,557
Other operating income	'	'	'	'
Service charges on deposit accounts	2,012	2,034	4,046	3,976
Lockbox fees	845	838	1,622	1,610
Net gains on sales of investments	'	781	'	1,664
Gains on sales of mortgage loans held for sale	81	821	88	991
Other income	677	747	1,329	1,414
Total other operating income	3,615	5,221	7,085	9,655
Operating expenses	'	'	'	'
Salaries and employee benefits	8,776	8,382	17,651	17,000
Occupancy	1,322	1,193	2,764	2,475
Equipment	585	610	1,157	1,192
FDIC assessments	494	450	974	850
Other	2,912	3,027	5,702	5,610
Total operating expenses	14,089	13,662	28,248	27,127
Income before income taxes	5,830	5,321	11,055	10,085
Provision for income taxes	231	295	524	583
Net income	5,599	5,026	10,531	9,502
Class A Common Stock [Member]	'	'	'	'
Operating expenses	'	'	'	'
Net income	4,394	3,935	8,259	7,437
Share data:	'	'	'	'
Weighted average number of shares outstanding, basic	3,589,125	3,574,379	3,585,773	3,571,963
Weighted average number of shares outstanding, diluted	5,558,032	5,557,354	5,558,105	5,557,655
Basic earnings per share	$1.22	$1.10	$2.30	$2.08
Diluted earnings per share	$1.01	$0.90	$1.89	$1.71
Class B Common Stock [Member]	'	'	'	'
Operating expenses	'	'	'	'
Net income	$1,205	$1,091	$2,272	$2,065
Share data:	'	'	'	'
Weighted average number of shares outstanding, basic	1,967,580	1,982,180	1,970,880	1,984,530
Weighted average number of shares outstanding, diluted	1,967,580	1,982,180	1,970,880	1,984,530
Basic earnings per share	$0.61	$0.55	$1.15	$1.04
Diluted earnings per share	$0.61	$0.55	$1.15	$1.04

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (unaudited) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement Of Income And Comprehensive Income [Abstract]	'	'	'	'
Net income	$5,599	$5,026	$10,531	$9,502
Unrealized gains (losses) on securities:	'	'	'	'
Unrealized gains (losses) arising and transferred during period	262	-18,656	505	-20,889
Less: reclassification adjustment for gains included in net income	'	-781	'	-1,664
Total unrealized gains (losses) on securities	262	-19,437	505	-22,553
Accretion of net unrealized losses transferred	808	'	1,732	'
Defined benefit pension plans:	'	'	'	'
Amortization of prior service cost and loss included in net periodic benefit cost	56	174	113	347
Other comprehensive income (loss)	1,126	-19,263	2,350	-22,206
Comprehensive income (loss)	$6,725	($14,237)	$12,881	($12,704)

Consolidated_Statements_of_Cha

Consolidated Statements of Changes in Shareholders' Equity (unaudited) (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 Income (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 Income (Loss) [Member]
Beginning balance at Dec. 31, 2012	$179,990	$3,568	$1,986	$11,891	$162,892	'	'	($347)
Net income	9,502	7,437	2,065	'	9,502	'	'	'
Other comprehensive income, net of tax:	'	'	'	'	'	'	'	'
Unrealized holding (losses) gains arising during period, net of taxes	-22,553	'	'	'	'	'	'	-22,553
Pension liability adjustment, net of taxes	347	'	'	'	'	'	'	347
Conversion of class B common stock to class A common stock	'	4	-4	'	'	'	'	'
Stock options exercised	42	2	'	40	'	'	'	'
Cash dividends	'	-857	-238	'	'	-857	-238	'
Ending balance at Jun. 30, 2013	166,233	3,574	1,982	11,931	171,299	'	'	-22,553
Beginning balance at Mar. 31, 2013	'	'	'	'	'	'	'	'
Net income	5,026	3,935	1,091	'	'	'	'	'
Other comprehensive income, net of tax:	'	'	'	'	'	'	'	'
Unrealized holding (losses) gains arising during period, net of taxes	-19,437	'	'	'	'	'	'	'
Ending balance at Jun. 30, 2013	166,233	3,574	1,982	'	'	'	'	'
Beginning balance at Dec. 31, 2013	176,472	3,580	1,976	11,932	180,747	'	'	-21,763
Net income	10,531	8,259	2,272	'	10,531	'	'	'
Other comprehensive income, net of tax:	'	'	'	'	'	'	'	'
Unrealized holding (losses) gains arising during period, net of taxes	505	'	'	'	'	'	'	505
Accretion of unrealized losses on securities transferred to held-to-maturity, net of in taxes	1,732	'	'	'	'	'	'	1,732
Pension liability adjustment, net of taxes	113	'	'	'	'	'	'	113
Conversion of class B common stock to class A common stock	'	8	-8	'	'	'	'	'
Stock options exercised	4	1	'	3	'	'	'	'
Cash dividends	'	-859	-237	'	'	-859	-237	'
Ending balance at Jun. 30, 2014	188,261	3,589	1,968	11,935	190,182	'	'	-19,413
Beginning balance at Mar. 31, 2014	'	'	'	'	'	'	'	'
Net income	5,599	4,394	1,205	'	'	'	'	'
Other comprehensive income, net of tax:	'	'	'	'	'	'	'	'
Unrealized holding (losses) gains arising during period, net of taxes	262	'	'	'	'	'	'	'
Ending balance at Jun. 30, 2014	$188,261	$3,589	$1,968	'	'	'	'	'

Consolidated_Statements_of_Cha1

Consolidated Statements of Changes in Shareholders' Equity (unaudited) (Parenthetical) (USD $)	6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Unrealized holding (losses) gains arising during period, taxes	$339	$14,372
Accretion of unrealized losses on securities transferred to held-to-maturity, taxes	1,061	'
Realized net gains	'	1,664
Pension liability adjustment, taxes	$75	$231
Conversion of class B common stock to class A common stock, shares	8,600	4,700
Stock options exercised, shares	125	1,600
Class A Common Stock [Member]	'	'
Cash dividends paid, per share	$0.24	$0.24
Class B Common Stock [Member]	'	'
Cash dividends paid, per share	$0.12	$0.12

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (unaudited) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:	'	'
Net income	$10,531	$9,502
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Mortgage loans originated for sale	-5,994	-56,001
Proceeds from mortgage loans sold	6,082	50,010
Gain on sales of mortgage loans held for sale	-88	-991
Net gain on sales of investments	'	-1,664
Provision for loan losses	1,050	1,500
Deferred income taxes	-1,547	-823
Net depreciation and amortization	1,630	3,058
Increase in accrued interest receivable	-175	-194
Increase in other assets	-2,192	-2,203
Increase in other liabilities	454	2,353
Net cash provided by operating activities	9,751	4,547
CASH FLOWS FROM INVESTING ACTIVITIES:	'	'
Proceeds from maturities of short-term investments	3,561	6,317
Purchase of short-term investments	-1,069	-8,561
Proceeds from calls/maturities of securities available-for-sale	71,155	174,303
Proceeds from sales of securities available-for-sale	'	163,593
Purchase of securities available-for-sale	-100,084	-482,373
Proceeds from calls/maturities of securities held-to-maturity	106,312	37,453
Purchase of securities held-to-maturity	-152,901	-29,825
Net increase in loans	-49,707	-45,143
Capital expenditures	-1,252	-658
Net cash used in investing activities	-123,985	-184,894
CASH FLOWS FROM FINANCING ACTIVITIES:	'	'
Net increase in time deposits	5,965	46,509
Net increase in demand, savings, money market and NOW deposits	128,534	149,613
Net proceeds from exercise of stock options	4	42
Cash dividends	-1,096	-1,095
Net (decrease) increase in securities sold under agreements to repurchase	-34,430	22,900
Net increase (decrease) in other borrowed funds	12,356	-18,000
Net cash provided by financing activities	111,333	199,969
Net (decrease) increase in cash and cash equivalents	-2,901	19,622
Cash and cash equivalents at beginning of period	94,678	152,283
Cash and cash equivalents at end of period	91,777	171,905
Cash paid during the period for:	'	'
Cash paid during the period for interest	9,421	9,317
Cash paid during the period for income taxes	1,991	1,550
Change in unrealized (losses) gains on securities available-for-sale, net of taxes	505	-22,553
Change in unrealized losses on securities transferred to held-to-maturity, net of taxes	1,732	'
Pension liability adjustment, net of taxes	113	347
Due to broker	$2,000	$10,711

Basis_of_Financial_Statement_P

Basis of Financial Statement Presentation	6 Months Ended
Basis of Financial Statement Presentation	Jun. 30, 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	6 Months Ended
Recent Market Developments	Jun. 30, 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 risk-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.

Stock_Option_Accounting

Stock Option Accounting	6 Months Ended
Stock Option Accounting	Jun. 30, 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 six months ended June 30, 2014 is as follows:


		Amount			Weighted
					Average
					Exercise
					Price
	Shares under option:
	Outstanding at beginning of year		20,225		$	31.82
	Exercised		(125	)		31.83
	Forfeited		—			—

	Outstanding at end of period		20,100		$	31.82

	Exercisable at end of period		20,100		$	31.82

	Available to be granted at end of period		225,034

	On June 30, 2014, the outstanding options to purchase 20,100 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 0.25 years. The intrinsic value of options exercisable at June 30, 2014 had an aggregate value of $70,551. The intrinsic value of options exercised at June 30, 2014 had an aggregate value of $439.
	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 six months of 2014.

Securities_AvailableforSale

Securities Available-for-Sale	6 Months Ended
Securities Available-for-Sale	Jun. 30, 2014
Text Block [Abstract]	'
Securities Available-for-Sale	'
	Note 4. Securities Available-for-Sale


			June 30, 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		$	3		$	—		$	2,001		$	1,997		$	1	$	—	$	1,998
	U.S. Government Sponsored Enterprises			—			—			—			—			9,995			9		—		10,004
	Small Business Administration			6,915			58			—			6,973			7,270			32		—		7,302
	U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities			419,732			1,039			1,146			419,625			404,103			588		1,501		403,190
	Privately Issued Residential Mortgage Backed Securities			2,122			16			11			2,127			2,294			6		23		2,277
	Obligations Issued by States and Political Subdivisions			61,768			5			871			60,902			37,578			15		870		36,723
	Other Debt Securities			2,300			—			120			2,180			2,300			—		125		2,175
	Equity Securities			327			174			—			501			406			170		—		576

	Total		$	495,162		$	1,295		$	2,148		$	494,309		$	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 $346,459,000 and $368,137,000 at June 30, 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 $34,242,000 and $12,214,000 at June 30, 2014 and December 31, 2013, respectively. There were no realized gains on sales of investments for the six months ended June 30, 2014. The Company realized gross gains of $1,664,000 from the proceeds of $163,593,000 from the sales of available-for-sale securities for the six months ended June 30, 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 June 30, 2014.


			Amortized			Fair
			Cost			Value
			( In thousands)
	Within one year		$	55,709		$	55,728
	After one but within five years			239,010			239,068
	After five but within ten years			189,203			188,968
	More than 10 years			9,413			8,664
	Non-maturing			1,827			1,881

	Total		$	495,162		$	494,309

	The weighted average remaining life of investment securities available-for-sale at June 30, 2014 was 4.6 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 June 30, 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 June 30, 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 27 and 14 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 254 holdings at June 30, 2014.


			June 30, 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			166,346			764			66,805			382			233,151			1,146
	Privately Issued Residential Mortgage Backed Securities			—			—			793			11			793			11
	Obligations Issued by States and Political Subdivisions			—			—			3,820			871			3,820			871
	Other Debt Securities			—			—			1,380			120			1,380			120

	Total temporarily impaired securities		$	166,346		$	764		$	72,798		$	1,384		$	239,144		$	2,148

	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	6 Months Ended
Investment Securities Held-to-Maturity	Jun. 30, 2014
Text Block [Abstract]	'
Investment Securities Held-to-Maturity	'
	Note 5. Investment Securities Held-to-Maturity


		June 30, 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	$	328,351	$	2,021	$	633	$	329,739	$	291,779	$	185	$	5,043	$	286,921
	U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities		1,208,637		9,516		10,053		1,208,100		1,196,105		2,239		20,816		1,177,528

	Total	$	1,536,988	$	11,537	$	10,686	$	1,537,839	$	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 $746,339,000 and $732,144,000 at June 30, 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 $494,453,000 and $510,060,000 at June 30, 2014 and December 31, 2013, respectively.
	At June 30, 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 June 30, 2014.


		Amortized		Fair
		Cost		Value
		( In thousands)
	Within one year	$	4,464	$	4,512
	After one but within five years		1,042,137		1,042,271
	After five but within ten years		489,585		490,234
	More than ten years		802		822

	Total	$	1,536,988	$	1,537,839

	The weighted average remaining life of investment securities held-to-maturity at June 30, 2014 was 4.8 years. Included in the weighted average remaining life calculation at June 30, 2014 were $260,065,000 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 June 30, 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 June 30, 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 June 30, 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 43 and 57 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 310 holdings at June 30, 2014.


		June 30, 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	$	61,736	$	232	$	29,161	$	401	$	90,897	$	633
	U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities		222,198		2,179		376,287		7,874		598,485		10,053

	Total temporarily impaired securities	$	283,934	$	2,411	$	405,448	$	8,275	$	689,382	$	10,686

	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		Unrealized		Fair Value		Unrealized
	Temporarily Impaired Investments	Fair Value		Losses		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	6 Months Ended
Allowance for Loan Losses	Jun. 30, 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								Six months ended
			June 30,								June 30,
			2014				2013				2014				2013
			(in thousands)
	Allowance for loan losses, beginning of period		$	21,259			$	19,759			$	20,941			$	19,197
	Loans charged off			(113	)			(160	)			(542	)			(533	)
	Recoveries on loans previously charged-off			126				151				273				336

	Net charge-offs			13				(9	)			(269	)			(197	)
	Provision charged to expense			450				750				1,050				1,500

	Allowance for loan losses, end of period		$	21,722			$	20,500			$	21,722			$	20,500


	Further information pertaining to the allowance for loan losses for the three months ending June 30, 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 March 31, 2014		$	1,825			$	3,090			$	11,874			$	1,873			$	425			$	902			$	1,270		$	21,259
	Charge-offs			—				(14	)			—				—				(99	)			—				—			(113	)
	Recoveries			—				24				2				15				84				1				—			126
	Provision			220				(185	)			99				39				18				12				247			450

	Ending balance at June 30, 2014		$	2,045			$	2,915			$	11,975			$	1,927			$	428			$	915			$	1,517		$	21,722

	Amount of allowance for loan losses for loans deemed to be impaired		$	273			$	353			$	359			$	160			$	—			$	93			$	—			1,238

	Amount of allowance for loan losses for loans not deemed to be impaired		$	1,772			$	2,562			$	11,616			$	1,767			$	428			$	822			$	1,517		$	20,484

	Loans:
	Ending balance		$	25,861			$	88,666			$	766,965			$	282,468			$	9,649			$	140,616			$	—		$	1,314,225

	Loans deemed to be impaired		$	356			$	1,093			$	4,775			$	1,559			$	—			$	93			$	—		$	7,876

	Loans not deemed to be impaired		$	25,505			$	87,573			$	762,190			$	280,909			$	9,649			$	140,523			$	—		$	1,306,349

	Further information pertaining to the allowance for loan losses for the six months ending June 30, 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	)			(14	)			—				—				(278	)			—				—			(542	)
	Recoveries			—				48				4				20				200				1				—			273
	Provision			121				(108	)			753				(99	)			74				(45	)			354			1,050

	Ending balance at June 30, 2014		$	2,045			$	2,915			$	11,975			$	1,927			$	428			$	915			$	1,517		$	21,722

	Amount of allowance for loan losses for loans deemed to be impaired		$	273			$	353			$	359			$	160			$	—			$	93			$	—			1,238

Amount of allowance for loan losses for loans not deemed to be impaired		$	1,772			$	2,562			$	11,616			$	1,767			$	428			$	822			$	1,517		$	20,484

Loans:
Ending balance		$	25,861			$	88,666			$	766,965			$	282,468			$	9,649			$	140,616			$	—		$	1,314,225

Loans deemed to be impaired		$	356			$	1,093			$	4,775			$	1,559			$	—			$	93			$	—		$	7,876

Loans not deemed to be impaired		$	25,505			$	87,573			$	762,190			$	280,909			$	9,649			$	140,523			$	—		$	1,306,349


Further information pertaining to the allowance for loan losses for the three months ending June 30, 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 March 31, 2013		$	3,199			$	3,523			$	8,779			$	2,071			$	357			$	833			$	997		$	19,759
Charge-offs			—				(6	)			—				—				(154	)			—				—			(160	)
Recoveries			—				56				1				1				92				1				—			151
Provision			42				(358	)			644				(42	)			68				98				298			750

Ending balance at June 30, 2013		$	3,241			$	3,215			$	9,424			$	2,030			$	363			$	932			$	1,295		$	20,500

Amount of allowance for loan losses for loans deemed to be impaired		$	1,000			$	92			$	204			$	147			$	—			$	96			$	—			1,539

Amount of allowance for loan losses for loans not deemed to be impaired		$	2,241			$	3,123			$	9,220			$	1,883			$	363			$	836			$	1,295		$	18,961

Loans:
Ending balance		$	34,919			$	101,918			$	609,462			$	283,392			$	8,123			$	125,918			$	—		$	1,163,732

Loans deemed to be impaired		$	1,500			$	1,102			$	2,365			$	1,171			$	—			$	96			$	—		$	6,234

Loans not deemed to be impaired		$	33,419			$	100,816			$	607,097			$	282,221			$	8,123			$	125,822			$	—		$	1,157,498

Further information pertaining to the allowance for loan losses for the six months ending June 30, 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			—				(234	)			—				—				(299	)			—				—			(533	)
Recoveries			—				121				4				4				206				1				—			336
Provision			200				210				355				32				123				45				535			1,500

Ending balance at June 30, 2013		$	3,241			$	3,215			$	9,424			$	2,030			$	363			$	932			$	1,295		$	20,500

Amount of allowance for loan losses for loans deemed to be impaired		$	1,000			$	92			$	204			$	147			$	—			$	96			$	—			1,539

Amount of allowance for loan losses for loans not deemed to be impaired		$	2,241			$	3,123			$	9,220			$	1,883			$	363			$	836			$	1,295		$	18,961

Loans:
Ending balance		$	34,919			$	101,918			$	609,462			$	283,392			$	8,123			$	125,918			$	—		$	1,163,732

Loans deemed to be impaired		$	1,500			$	1,102			$	2,365			$	1,171			$	—			$	96			$	—		$	6,234

Loans not deemed to be impaired		$	33,419			$	100,816			$	607,097			$	282,221			$	8,123			$	125,822			$	—		$	1,157,498


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 June 30, 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 June 30, 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 June 30, 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 June 30, 2014.


		Construction				Commercial				Commercial
		and land				and				real
		development				industrial				estate
		(Dollars in thousands)
Grade:
1-3 (Pass)		$	18,283			$	87,101			$	761,273
4 (Monitor)			7,222				472				917
5 (Substandard)			—				—				—
6 (Doubtful)			—				—				—
Impaired			356				1,093				4,775

Total		$	25,861			$	88,666			$	766,965

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 June 30, 2014 follows:


		Accruing				Non Accrual				Accrual				Total				Current				Total
		30-89								Greater				Past Due				Loans
		Days								Than
		Past Due								90 Days
		(Dollars in thousands)
Construction and land development		$	—			$	356			$	—			$	356			$	25,505			$	25,861
Commercial and industrial			1,051				450				—				1,501				87,165				88,666
Commercial real estate			2,570				610				614				3,794				763,171				766,965
Residential real estate			1,154				1,426				—				2,580				279,888				282,468
Consumer and overdrafts			1				3				—				4				9,645				9,649
Home equity			326				—				—				326				140,290				140,616

Total		$	5,102			$				$				$	8,561			$	1,305,664			$	1,314,225
Total		$	5,102			$	2,845			$	614			$	8,561			$	1,305,664			$	1,314,225

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


		Accruing				Non Accrual				Accrual				Total				Current				Total
		30-89								Greater				Past Due				Loans
		Days								Than
		Past Due								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 June 30, 2014:


		Carrying				Unpaid				Required				Average				Interest				Average				Interest
		Value				Principal				Reserve				Carrying				Income				Carrying Value				Income
						Balance								Value				Recognized				For 6 Months				Recognized
														For 3 Months				For 3 Months				Ending 6/30/14				For 6 Months
														Ending 6/30/14				Ending 6/30/14								Ending 6/30/14
		(Dollars in thousands)
With no required reserve recorded:
Construction and land development		$	—			$	—			$	—			$	188			$	—			$	321			$	—
Commercial and industrial			11				42				—				11				—				71				—
Commercial real estate			400				400				—				100				—				80				—
Residential real estate			70				70				—				31				—				104				—
Consumer			—				—				—				—				—				—				—
Home equity			—				—				—				—				—				—				—

Total		$	481			$	512			$	—			$	330			$	—			$	576			$	—

With required reserve recorded:
Construction and land development		$	356			$	3,400			$	273			$	169			$	—			$	143			$	—
Commercial and industrial			1,082				1,332				353				1,095				8				1,104				19
Commercial real estate			4,375				4,466				359				4,391				36				4,405				74
Residential real estate			1,489				1,684				160				1,106				3				1,039				5
Consumer			—				—				—				—				—				—				—
Home equity			93				93				93				94				—				94				—

Total		$	7,395			$	10,975			$	1,238			$	6,855			$	47			$	6,785			$	98


Total:
Construction and land development		$	356			$	3,400			$	273			$	357			$	—			$	465			$	—
Commercial and industrial			1,093				1,374				353				1,106				8				1,175				19
Commercial real estate			4,775				4,866				359				4,491				36				4,485				74
Residential real estate			1,559				1,754				160				1,137				3				1,143				5
Consumer			—				—				—				—				—				—				—
Home equity			93				93				93				94				—				94				—

Total		$	7,876			$	11,487			$	1,238			$	7,185			$	47			$	7,362			$	98

The following is information pertaining to impaired loans for June 30, 2013:


		Carrying				Unpaid				Required				Average Carrying				Average Carrying				Interest				Interest
		Value				Principal				Reserve				Value For 3				Value For 6				Income				Income
						Balance								Months				Months				Recognized				Recognized
														Ending 6/30/13				Ending 6/30/13				For 3 Months				For 6 Months
																						Ending 6/30/13				Ending 6/30/13
		(Dollars in thousands)
With no required reserve recorded:
Construction and land development		$	—			$	—			$	—			$	—			$	—			$	—			$	—
Commercial and industrial			206				235				—				385				451				1				1
Commercial real estate			122				122				—				113				136				—				—
Residential real estate			266				266				—				146				96				—				—
Consumer			—				—				—				—				—				—				—
Home equity			—				—				—				—				—				—				—

Total		$	594			$	623			$	—			$	644			$	683			$	1			$	1



With required reserve recorded:
Construction and land development		$	1,500			$	3,292			$	1,000			$	1,500			$	1,500			$	—			$	—
Commercial and industrial			896				1,128				92				866				856				8				17
Commercial real estate			2,243				2,330				204				2,169				2,143				20				46
Residential real estate			905				991				147				909				834				—				—
Consumer			—				—				—				—				—				—				—
Home equity			96				96				96				96				96				—				—

Total		$	5,640			$	7,837			$	1,539			$	5,540			$	5,429			$	28			$	63


Total:
Construction and land development		$	1,500			$	3,292			$	1,000			$	1,500			$	1,500			$	—			$	—
Commercial and industrial			1,102				1,363				92				1,251				1,307				9				18
Commercial real estate			2,365				2,452				204				2,282				2,279				20				46
Residential real estate			1,171				1,257				147				1,055				930				—				—
Consumer			—				—				—				—				—				—				—
Home equity			96				96				96				96				96				—				—

Total		$	6,234			$	8,460			$	1,539			$	6,184			$	6,112			$	29			$	64

There were no troubled debt restructurings occurring during the six month periods ended June 30, 2014 or June 30, 2013.

Reclassifications_Out_of_Accum

Reclassifications Out of Accumulated Other Comprehensive Income	6 Months Ended
	Jun. 30, 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		June 30, 2014				June 30, 2013				in the Statement
	Income Components										Where Net Income
											is Presented
			(in thousands)

	Unrealized gains and losses on available-for-sale securities
			$	—			$	781			Net gains on sales of investments
				—				(302	)		Provision for income taxes

			$	—			$	479			Net income


	Accretion of unrealized losses transferred
				$1,286			$	—			Securities held-to-maturity
				-478				—			Provision for income taxes

			$	808			$	—			Net income


	Amortization of defined benefit pension items

	Prior-service costs		$	(3	)(b)		$	(3	)		Salaries and employee benefits
	Actuarial gains (losses)			(91	)(b)			(287	)		Salaries and employee benefits

	Total before tax			(94	)			(290	)		Income before taxes
	Tax (expense) or benefit			38				116			Provision for income taxes

	Net of tax		$	(56	)		$	(174	)		Net income

	Total reclassifications for the period		$	752			$	305			Net income, net of tax



	Details about Accumulated		Six Months Ended				Six Months Ended				Affected Line Item
	Other Comprehensive		June 30, 2014				June 30, 2013				in the Statement
	Income Components										Where Net Income
											is Presented
			(in thousands)

	Unrealized gains and losses on available-for-sale securities
			$	—			$	1,664			Net gains on sales of investments
				—				(652	)		Provision for income taxes

			$	—			$	1,012			Net income


	Accretion of unrealized losses transferred
				$2,793			$	—			Securities held-to-maturity
				-1,061				—			Provision for income taxes

			$	1,732			$	—			Net income


	Amortization of defined benefit pension items

	Prior-service costs		$	(5	)(b)		$	(6	)		Salaries and employee benefits
	Actuarial gains (losses)			(183	)(b)			(574	)		Salaries and employee benefits

Total before tax			(188	)			(580	)		Income before taxes
Tax (expense) or benefit			75				233			Provision for income taxes

Net of tax		$	(113	)		$	(347	)		Net income

Total reclassifications for the period		$	1,619			$	665			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")	6 Months Ended
Earnings per Share ("EPS")	Jun. 30, 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 1,452 and 1,162 shares, respectively.

	The following table is a reconciliation of basic EPS and diluted EPS for the three and six months ended June 30,


		Three Months Ended				Six Months Ended
		June 30,				June 30,
		2014		2013		2014		2013
	(in thousands except share and per share data)
	Basic EPS Computation:
	Numerator:
	Net income, Class A	$	4,394	$	3,935	$	8,259	$	7,437
	Net income, Class B		1,205		1,091		2,272		2,065
	Denominator:
	Weighted average shares outstanding, Class A		3,589,125		3,574,379		3,585,773		3,571,963
	Weighted average shares outstanding, Class B		1,967,580		1,982,180		1,970,880		1,984,530
	Basic EPS, Class A	$	1.22	$	1.1	$	2.3	$	2.08
	Basic EPS, Class B		0.61		0.55		1.15		1.04
	Diluted EPS Computation:
	Numerator:
	Net income, Class A	$	4,394	$	3,935	$	8,259	$	7,437
	Net income, Class B		1,205		1,091		2,272		2,065

	Total net income, for diluted EPS, Class A computation		5,599		5,026		10,531		9,502
	Denominator:
	Weighted average shares outstanding, basic, Class A		3,589,125		3,574,379		3,585,773		3,571,963
	Weighted average shares outstanding, Class B		1,967,580		1,982,180		1,970,880		1,984,530
	Dilutive effect of Class A stock options		1,327		795		1,452		1,162

	Weighted average shares outstanding diluted, Class A		5,558,032		5,557,354		5,558,105		5,557,655
	Weighted average shares outstanding, Class B		1,967,580		1,982,180		1,970,880		1,984,530
	Diluted EPS, Class A	$	1.01	$	0.9	$	1.89	$	1.71
	Diluted EPS, Class B		0.61		0.55		1.15		1.04

Employee_Benefits

Employee Benefits	6 Months Ended
Employee Benefits	Jun. 30, 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 June 30,


		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


	Components of Net Periodic Benefit Cost (Credit) for the Six Months Ended June 30,


		Pension Benefits						Supplemental Insurance/
		Pension Benefits						Retirement Plan
		2014			2013			2014		2013
		(In thousands)
	Service cost	$	516		$	598		$	778	$	763
	Interest		734			628			662		534
	Expected return on plan assets		(1,272	)		(940	)		—		—
	Recognized prior service cost (benefit)		(52	)		(52	)		58		58
	Recognized net actuarial losses		6			316			176		258

	Net periodic benefit (credit) cost	$	(68	)	$	550		$	1,674	$	1,613

	Contributions
	As of June 30, 2014, $920,000 has been contributed. The Company does not anticipate making any additional contributions.

Fair_Value_Measurements

Fair Value Measurements	6 Months Ended
Fair Value Measurements	Jun. 30, 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 June 30, 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		$	2,001		$	—			$	2,001			$	—
	U.S. Government Sponsored Enterprises			—			—				—				—
	SBA Backed Securities			6,973			—				6,973				—
	U.S. Government Agency and Sponsored Mortgage Backed Securities			419,625			—				419,625				—
	Privately Issued Residential Mortgage Backed Securities			2,127			—				2,127				—
	Obligations Issued by States and Political Subdivisions			60,902			—				408				60,494
	Other Debt Securities			2,180			—				2,180				—
	Equity Securities			501			290				—				211

	Total		$	494,309		$	290			$	433,314			$	60,705

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


	Impaired Loans			2,539		—				—					2,539
	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 and six-month periods ended June 30, 2014 amounted to $276,000 and $530,000, respectively.
	There were no transfers between level 1 and 2 for the three months ended June 30, 2014. There were no liabilities measured at fair value on a recurring or nonrecurring basis during the six month period ended June 30, 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			Valuation Technique		Unobservable Input		Unobservable Input
	Asset		Value			Valuation Technique		Unobservable Input		Value or Range
	Securities AFS (4)		$	60,705		Discounted cash flow		Discount rate		0% -1% (3)
	Impaired Loans			2,539		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 six-month period ended June 30, 2014 are shown in the table below:


			Auction			Obligations				Equity				Total
			Rate			Issued by				Securities
			Securities			States &
						Political
						Subdivisions
						(In thousands)
	Balance at December 31, 2013		$	3,820			32,487			$	290			$	36,597
	Purchases			—			51,471				—				51,471
	Maturities and calls			—			(27,282	)			(79	)			(27,361	)
	Amortization			—			(2	)			—				(2	)
	Changes in fair value			—			—				—				—

Balance at June 30, 2014		$	3,820		$	56,674			$	211			$	60,705

The amortized cost of Level 3 securities was $61,577,000 at June 30, 2014 with an unrealized loss of $872,000. 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 six-month period ended June 30, 2013, are shown in the table below:


		Auction			Obligations				Equity				Total
		Rate			Issued by				Securities
		Securities			States &
					Political
					Subdivisions
					(In thousands)
Balance at December 31, 2012		$	3,963		$	49,477			$	342			$	53,782
Purchases			—			29,370				—				29,370
Maturities and calls			—			(30,830	)			(10	)			(30,840	)
Amortization			—			(18	)			—				(18	)
Changes in fair value			—			—				—				—

Balance at June 30, 2013		$	3,963		$	47,999			$	332			$	52,294

The amortized cost of Level 3 securities was $53,018,000 at June 30, 2013 with an unrealized loss of $724,000. 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	6 Months Ended
Fair Values of Financial Instruments	Jun. 30, 2014
Investments All Other Investments [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 June 30, 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
	June 30, 2014		Carrying Amount		Estimated		Level 1		Level 2		Level 3
	June 30, 2014		Carrying Amount		Fair Value		Inputs		Inputs		Inputs
	(in thousands)
	Financial assets:
	Securities held-to-maturity		$	1,536,988	$	1,537,839	$	—	$	1,537,839	$	—
	Loans (1)			1,292,503		1,269,530		—		—		1,269,530
	Financial liabilities:
	Time deposits			388,189		393,502		—		393,502		—
	Other borrowed funds			267,500		270,576		—		270,576		—
	Subordinated debentures			36,083		41,036		—		—		41,036

	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	6 Months Ended
Recent Accounting Developments	Jun. 30, 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)	6 Months Ended
Fair Value Measurements (Policies)	Jun. 30, 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	'
	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)	6 Months Ended
Stock Option Accounting (Tables)	Jun. 30, 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 six months ended June 30, 2014 is as follows:


		Amount			Weighted
					Average
					Exercise
					Price
	Shares under option:
	Outstanding at beginning of year		20,225		$	31.82
	Exercised		(125	)		31.83
	Forfeited		—			—

	Outstanding at end of period		20,100		$	31.82

	Exercisable at end of period		20,100		$	31.82

	Available to be granted at end of period		225,034

Securities_AvailableforSale_Ta

Securities Available-for-Sale (Tables)	6 Months Ended
Securities Available-for-Sale (Tables)	Jun. 30, 2014
Text Block [Abstract]	'
Summary of Securities Available-for-Sale	'

		June 30, 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	$	3	$	—	$	2,001	$	1,997	$	1	$	—	$	1,998
	U.S. Government Sponsored Enterprises		—		—		—		—		9,995		9		—		10,004
	Small Business Administration		6,915		58		—		6,973		7,270		32		—		7,302
	U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities		419,732		1,039		1,146		419,625		404,103		588		1,501		403,190
	Privately Issued Residential Mortgage Backed Securities		2,122		16		11		2,127		2,294		6		23		2,277
	Obligations Issued by States and Political Subdivisions		61,768		5		871		60,902		37,578		15		870		36,723
	Other Debt Securities		2,300		—		120		2,180		2,300		—		125		2,175
	Equity Securities		327		174		—		501		406		170		—		576

	Total	$	495,162	$	1,295	$	2,148	$	494,309	$	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 June 30, 2014.


		Amortized		Fair
		Cost		Value
		( In thousands)
	Within one year	$	55,709	$	55,728
	After one but within five years		239,010		239,068
	After five but within ten years		189,203		188,968
	More than 10 years		9,413		8,664
	Non-maturing		1,827		1,881

	Total	$	495,162	$	494,309

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 June 30, 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 27 and 14 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 254 holdings at June 30, 2014.


		June 30, 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		166,346		764		66,805		382		233,151		1,146
	Privately Issued Residential Mortgage Backed Securities		—		—		793		11		793		11
	Obligations Issued by States and Political Subdivisions		—		—		3,820		871		3,820		871
	Other Debt Securities		—		—		1,380		120		1,380		120

	Total temporarily impaired securities	$	166,346	$	764	$	72,798	$	1,384	$	239,144	$	2,148

	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)	6 Months Ended
Investment Securities Held-to-Maturity (Tables)	Jun. 30, 2014
Text Block [Abstract]	'
Summary of Held-to-Maturity Securities	'

		June 30, 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	$	328,351	$	2,021	$	633	$	329,739	$	291,779	$	185	$	5,043	$	286,921
	U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities		1,208,637		9,516		10,053		1,208,100		1,196,105		2,239		20,816		1,177,528

	Total	$	1,536,988	$	11,537	$	10,686	$	1,537,839	$	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 June 30, 2014.


		Amortized		Fair
		Cost		Value
		( In thousands)
	Within one year	$	4,464	$	4,512
	After one but within five years		1,042,137		1,042,271
	After five but within ten years		489,585		490,234
	More than ten years		802		822

	Total	$	1,536,988	$	1,537,839

Unrealized Market Loss of Securities	'
	The following table shows the temporarily impaired securities of the Company’s held-to-maturity portfolio at June 30, 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 43 and 57 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 310 holdings at June 30, 2014.


		June 30, 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	$	61,736	$	232	$	29,161	$	401	$	90,897	$	633
	U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities		222,198		2,179		376,287		7,874		598,485		10,053

	Total temporarily impaired securities	$	283,934	$	2,411	$	405,448	$	8,275	$	689,382	$	10,686

	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		Unrealized		Fair Value		Unrealized
	Temporarily Impaired Investments	Fair Value		Losses		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)	6 Months Ended
Allowance for Loan Losses (Tables)	Jun. 30, 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								Six months ended
			June 30,								June 30,
			2014				2013				2014				2013
			(in thousands)
	Allowance for loan losses, beginning of period		$	21,259			$	19,759			$	20,941			$	19,197
	Loans charged off			(113	)			(160	)			(542	)			(533	)
	Recoveries on loans previously charged-off			126				151				273				336

	Net charge-offs			13				(9	)			(269	)			(197	)
	Provision charged to expense			450				750				1,050				1,500

	Allowance for loan losses, end of period		$	21,722			$	20,500			$	21,722			$	20,500

Summary of Allowance for Loan Losses	'
	Further information pertaining to the allowance for loan losses for the three months ending June 30, 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 March 31, 2014		$	1,825			$	3,090			$	11,874			$	1,873			$	425			$	902			$	1,270		$	21,259
	Charge-offs			—				(14	)			—				—				(99	)			—				—			(113	)
	Recoveries			—				24				2				15				84				1				—			126
	Provision			220				(185	)			99				39				18				12				247			450

	Ending balance at June 30, 2014		$	2,045			$	2,915			$	11,975			$	1,927			$	428			$	915			$	1,517		$	21,722

	Amount of allowance for loan losses for loans deemed to be impaired		$	273			$	353			$	359			$	160			$	—			$	93			$	—			1,238

	Amount of allowance for loan losses for loans not deemed to be impaired		$	1,772			$	2,562			$	11,616			$	1,767			$	428			$	822			$	1,517		$	20,484

	Loans:
	Ending balance		$	25,861			$	88,666			$	766,965			$	282,468			$	9,649			$	140,616			$	—		$	1,314,225

	Loans deemed to be impaired		$	356			$	1,093			$	4,775			$	1,559			$	—			$	93			$	—		$	7,876

	Loans not deemed to be impaired		$	25,505			$	87,573			$	762,190			$	280,909			$	9,649			$	140,523			$	—		$	1,306,349

	Further information pertaining to the allowance for loan losses for the six months ending June 30, 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	)			(14	)			—				—				(278	)			—				—			(542	)
	Recoveries			—				48				4				20				200				1				—			273
	Provision			121				(108	)			753				(99	)			74				(45	)			354			1,050

	Ending balance at June 30, 2014		$	2,045			$	2,915			$	11,975			$	1,927			$	428			$	915			$	1,517		$	21,722

	Amount of allowance for loan losses for loans deemed to be impaired		$	273			$	353			$	359			$	160			$	—			$	93			$	—			1,238

	Amount of allowance for loan losses for loans not deemed to be impaired		$	1,772			$	2,562			$	11,616			$	1,767			$	428			$	822			$	1,517		$	20,484

	Loans:
	Ending balance		$	25,861			$	88,666			$	766,965			$	282,468			$	9,649			$	140,616			$	—		$	1,314,225

	Loans deemed to be impaired		$	356			$	1,093			$	4,775			$	1,559			$	—			$	93			$	—		$	7,876

	Loans not deemed to be impaired		$	25,505			$	87,573			$	762,190			$	280,909			$	9,649			$	140,523			$	—		$	1,306,349


	Further information pertaining to the allowance for loan losses for the three months ending June 30, 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 March 31, 2013		$	3,199			$	3,523			$	8,779			$	2,071			$	357			$	833			$	997		$	19,759
	Charge-offs			—				(6	)			—				—				(154	)			—				—			(160	)
Recoveries			—				56				1				1				92				1				—			151
Provision			42				(358	)			644				(42	)			68				98				298			750

Ending balance at June 30, 2013		$	3,241			$	3,215			$	9,424			$	2,030			$	363			$	932			$	1,295		$	20,500

Amount of allowance for loan losses for loans deemed to be impaired		$	1,000			$	92			$	204			$	147			$	—			$	96			$	—			1,539

Amount of allowance for loan losses for loans not deemed to be impaired		$	2,241			$	3,123			$	9,220			$	1,883			$	363			$	836			$	1,295		$	18,961

Loans:
Ending balance		$	34,919			$	101,918			$	609,462			$	283,392			$	8,123			$	125,918			$	—		$	1,163,732

Loans deemed to be impaired		$	1,500			$	1,102			$	2,365			$	1,171			$	—			$	96			$	—		$	6,234

Loans not deemed to be impaired		$	33,419			$	100,816			$	607,097			$	282,221			$	8,123			$	125,822			$	—		$	1,157,498

Further information pertaining to the allowance for loan losses for the six months ending June 30, 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			—				(234	)			—				—				(299	)			—				—			(533	)
Recoveries			—				121				4				4				206				1				—			336
Provision			200				210				355				32				123				45				535			1,500

Ending balance at June 30, 2013		$	3,241			$	3,215			$	9,424			$	2,030			$	363			$	932			$	1,295		$	20,500

Amount of allowance for loan losses for loans deemed to be impaired		$	1,000			$	92			$	204			$	147			$	—			$	96			$	—			1,539

Amount of allowance for loan losses for loans not deemed to be impaired		$	2,241			$	3,123			$	9,220			$	1,883			$	363			$	836			$	1,295		$	18,961

Loans:
Ending balance		$	34,919			$	101,918			$	609,462			$	283,392			$	8,123			$	125,918			$	—		$	1,163,732

Loans deemed to be impaired		$	1,500			$	1,102			$	2,365			$	1,171			$	—			$	96			$	—		$	6,234

Loans not deemed to be impaired		$	33,419			$	100,816			$	607,097			$	282,221			$	8,123			$	125,822			$	—		$	1,157,498

Loans by Risk Rating	'
	The following table presents the Company’s loans by risk rating at June 30, 2014.


			Construction				Commercial				Commercial
			and land				and				real
			development				industrial				estate
			(Dollars in thousands)
	Grade:
	1-3 (Pass)		$	18,283			$	87,101			$	761,273
	4 (Monitor)			7,222				472				917
	5 (Substandard)			—				—				—
	6 (Doubtful)			—				—				—
	Impaired			356				1,093				4,775

	Total		$	25,861			$	88,666			$	766,965

	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 June 30, 2014 follows:


			Accruing				Non Accrual				Accrual				Total				Current				Total
			30-89								Greater				Past Due				Loans
			Days								Than
			Past Due								90 Days
			(Dollars in thousands)
	Construction and land development		$	—			$	356			$	—			$	356			$	25,505			$	25,861
	Commercial and industrial			1,051				450				—				1,501				87,165				88,666
	Commercial real estate			2,570				610				614				3,794				763,171				766,965
	Residential real estate			1,154				1,426				—				2,580				279,888				282,468
	Consumer and overdrafts			1				3				—				4				9,645				9,649
	Home equity			326				—				—				326				140,290				140,616

	Total		$	5,102			$				$				$	8,561			$	1,305,664			$	1,314,225
	Total		$	5,102			$	2,845			$	614			$	8,561			$	1,305,664			$	1,314,225

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


			Accruing				Non Accrual				Accrual				Total				Current				Total
			30-89								Greater				Past Due				Loans
			Days								Than
			Past Due								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 June 30, 2014:


			Carrying				Unpaid				Required				Average				Interest				Average				Interest
			Value				Principal				Reserve				Carrying				Income				Carrying Value				Income
							Balance								Value				Recognized				For 6 Months				Recognized
															For 3 Months				For 3 Months				Ending 6/30/14				For 6 Months
															Ending 6/30/14				Ending 6/30/14								Ending 6/30/14
			(Dollars in thousands)
	With no required reserve recorded:
	Construction and land development		$	—			$	—			$	—			$	188			$	—			$	321			$	—
	Commercial and industrial			11				42				—				11				—				71				—
	Commercial real estate			400				400				—				100				—				80				—
	Residential real estate			70				70				—				31				—				104				—
	Consumer			—				—				—				—				—				—				—
	Home equity			—				—				—				—				—				—				—

	Total		$	481			$	512			$	—			$	330			$	—			$	576			$	—

	With required reserve recorded:
	Construction and land development		$	356			$	3,400			$	273			$	169			$	—			$	143			$	—
	Commercial and industrial			1,082				1,332				353				1,095				8				1,104				19
	Commercial real estate			4,375				4,466				359				4,391				36				4,405				74
	Residential real estate			1,489				1,684				160				1,106				3				1,039				5
	Consumer			—				—				—				—				—				—				—
	Home equity			93				93				93				94				—				94				—

	Total		$	7,395			$	10,975			$	1,238			$	6,855			$	47			$	6,785			$	98


	Total:
	Construction and land development		$	356			$	3,400			$	273			$	357			$	—			$	465			$	—
	Commercial and industrial			1,093				1,374				353				1,106				8				1,175				19
	Commercial real estate			4,775				4,866				359				4,491				36				4,485				74
	Residential real estate			1,559				1,754				160				1,137				3				1,143				5
	Consumer			—				—				—				—				—				—				—
	Home equity			93				93				93				94				—				94				—

	Total		$	7,876			$	11,487			$	1,238			$	7,185			$	47			$	7,362			$	98

	The following is information pertaining to impaired loans for June 30, 2013:


			Carrying				Unpaid				Required				Average Carrying				Average Carrying				Interest				Interest
			Value				Principal				Reserve				Value For 3				Value For 6				Income				Income
							Balance								Months				Months				Recognized				Recognized
															Ending 6/30/13				Ending 6/30/13				For 3 Months				For 6 Months
																							Ending 6/30/13				Ending 6/30/13
			(Dollars in thousands)
	With no required reserve recorded:
	Construction and land development		$	—			$	—			$	—			$	—			$	—			$	—			$	—
	Commercial and industrial			206				235				—				385				451				1				1
	Commercial real estate			122				122				—				113				136				—				—
	Residential real estate			266				266				—				146				96				—				—
	Consumer			—				—				—				—				—				—				—
	Home equity			—				—				—				—				—				—				—

	Total		$	594			$	623			$	—			$	644			$	683			$	1			$	1



	With required reserve recorded:
	Construction and land development		$	1,500			$	3,292			$	1,000			$	1,500			$	1,500			$	—			$	—
Commercial and industrial			896				1,128				92				866				856				8				17
Commercial real estate			2,243				2,330				204				2,169				2,143				20				46
Residential real estate			905				991				147				909				834				—				—
Consumer			—				—				—				—				—				—				—
Home equity			96				96				96				96				96				—				—

Total		$	5,640			$	7,837			$	1,539			$	5,540			$	5,429			$	28			$	63


Total:
Construction and land development		$	1,500			$	3,292			$	1,000			$	1,500			$	1,500			$	—			$	—
Commercial and industrial			1,102				1,363				92				1,251				1,307				9				18
Commercial real estate			2,365				2,452				204				2,282				2,279				20				46
Residential real estate			1,171				1,257				147				1,055				930				—				—
Consumer			—				—				—				—				—				—				—
Home equity			96				96				96				96				96				—				—

Total		$	6,234			$	8,460			$	1,539			$	6,184			$	6,112			$	29			$	64

Reclassifications_Out_of_Accum1

Reclassifications Out of Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 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		June 30, 2014				June 30, 2013				in the Statement
	Income Components										Where Net Income
											is Presented
			(in thousands)

	Unrealized gains and losses on available-for-sale securities
			$	—			$	781			Net gains on sales of investments
				—				(302	)		Provision for income taxes

			$	—			$	479			Net income


	Accretion of unrealized losses transferred
				$1,286			$	—			Securities held-to-maturity
				-478				—			Provision for income taxes

			$	808			$	—			Net income


	Amortization of defined benefit pension items

	Prior-service costs		$	(3	)(b)		$	(3	)		Salaries and employee benefits
	Actuarial gains (losses)			(91	)(b)			(287	)		Salaries and employee benefits

	Total before tax			(94	)			(290	)		Income before taxes
	Tax (expense) or benefit			38				116			Provision for income taxes

	Net of tax		$	(56	)		$	(174	)		Net income

	Total reclassifications for the period		$	752			$	305			Net income, net of tax



	Details about Accumulated		Six Months Ended				Six Months Ended				Affected Line Item
	Other Comprehensive		June 30, 2014				June 30, 2013				in the Statement
	Income Components										Where Net Income
											is Presented
			(in thousands)

	Unrealized gains and losses on available-for-sale securities
			$	—			$	1,664			Net gains on sales of investments
				—				(652	)		Provision for income taxes

			$	—			$	1,012			Net income


	Accretion of unrealized losses transferred
				$2,793			$	—			Securities held-to-maturity
				-1,061				—			Provision for income taxes

			$	1,732			$	—			Net income


	Amortization of defined benefit pension items

	Prior-service costs		$	(5	)(b)		$	(6	)		Salaries and employee benefits
	Actuarial gains (losses)			(183	)(b)			(574	)		Salaries and employee benefits

	Total before tax			(188	)			(580	)		Income before taxes
Tax (expense) or benefit			75				233			Provision for income taxes

Net of tax		$	(113	)		$	(347	)		Net income

Total reclassifications for the period		$	1,619			$	665			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)	6 Months Ended
Earnings per Share ("EPS") (Tables)	Jun. 30, 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 and six months ended June 30,


		Three Months Ended				Six Months Ended
		June 30,				June 30,
		2014		2013		2014		2013
	(in thousands except share and per share data)
	Basic EPS Computation:
	Numerator:
	Net income, Class A	$	4,394	$	3,935	$	8,259	$	7,437
	Net income, Class B		1,205		1,091		2,272		2,065
	Denominator:
	Weighted average shares outstanding, Class A		3,589,125		3,574,379		3,585,773		3,571,963
	Weighted average shares outstanding, Class B		1,967,580		1,982,180		1,970,880		1,984,530
	Basic EPS, Class A	$	1.22	$	1.1	$	2.3	$	2.08
	Basic EPS, Class B		0.61		0.55		1.15		1.04
	Diluted EPS Computation:
	Numerator:
	Net income, Class A	$	4,394	$	3,935	$	8,259	$	7,437
	Net income, Class B		1,205		1,091		2,272		2,065

	Total net income, for diluted EPS, Class A computation		5,599		5,026		10,531		9,502
	Denominator:
	Weighted average shares outstanding, basic, Class A		3,589,125		3,574,379		3,585,773		3,571,963
	Weighted average shares outstanding, Class B		1,967,580		1,982,180		1,970,880		1,984,530
	Dilutive effect of Class A stock options		1,327		795		1,452		1,162

	Weighted average shares outstanding diluted, Class A		5,558,032		5,557,354		5,558,105		5,557,655
	Weighted average shares outstanding, Class B		1,967,580		1,982,180		1,970,880		1,984,530
	Diluted EPS, Class A	$	1.01	$	0.9	$	1.89	$	1.71
	Diluted EPS, Class B		0.61		0.55		1.15		1.04

Employee_Benefits_Tables

Employee Benefits (Tables)	6 Months Ended
Employee Benefits (Tables)	Jun. 30, 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 June 30,


		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


	Components of Net Periodic Benefit Cost (Credit) for the Six Months Ended June 30,


		Pension Benefits						Supplemental Insurance/
		Pension Benefits						Retirement Plan
		2014			2013			2014		2013
		(In thousands)
	Service cost	$	516		$	598		$	778	$	763
	Interest		734			628			662		534
	Expected return on plan assets		(1,272	)		(940	)		—		—
	Recognized prior service cost (benefit)		(52	)		(52	)		58		58
	Recognized net actuarial losses		6			316			176		258

	Net periodic benefit (credit) cost	$	(68	)	$	550		$	1,674	$	1,613

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	6 Months Ended
Fair Value Measurements (Tables)	Jun. 30, 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 June 30, 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		$	2,001	$	—		$	2,001		$	—
	U.S. Government Sponsored Enterprises			—		—			—			—
	SBA Backed Securities			6,973		—			6,973			—
	U.S. Government Agency and Sponsored Mortgage Backed Securities			419,625		—			419,625			—
	Privately Issued Residential Mortgage Backed Securities			2,127		—			2,127			—
	Obligations Issued by States and Political Subdivisions			60,902		—			408			60,494
	Other Debt Securities			2,180		—			2,180			—
	Equity Securities			501		290			—			211

	Total		$	494,309	$	290		$	433,314		$	60,705


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

	Impaired Loans			2,539		—			—			2,539
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		Valuation Technique		Unobservable Input	Unobservable Input
	Asset		Value		Valuation Technique		Unobservable Input	Value or Range
	Securities AFS (4)		$	60,705	Discounted cash flow		Discount rate	0% -1% (3)
	Impaired Loans			2,539	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 six-month period ended June 30, 2014 are shown in the table below:


			Auction		Obligations			Equity			Total
			Rate		Issued by			Securities
			Securities		States &
					Political
					Subdivisions
					(In thousands)
	Balance at December 31, 2013		$	3,820		32,487		$	290		$	36,597
	Purchases			—		51,471			—			51,471
	Maturities and calls			—		(27,282	)		(79	)		(27,361	)
	Amortization			—		(2	)		—			(2	)
	Changes in fair value			—		—			—			—

	Balance at June 30, 2014		$	3,820	$	56,674		$	211		$	60,705


	The changes in Level 3 securities for the six-month period ended June 30, 2013, are shown in the table below:


			Auction		Obligations			Equity			Total
			Rate		Issued by			Securities
			Securities		States &
					Political
					Subdivisions
					(In thousands)
	Balance at December 31, 2012		$	3,963	$	49,477		$	342		$	53,782
	Purchases			—		29,370			—			29,370
	Maturities and calls			—		(30,830	)		(10	)		(30,840	)
	Amortization			—		(18	)		—			(18	)
	Changes in fair value			—		—			—			—

	Balance at June 30, 2013		$	3,963	$	47,999		$	332		$	52,294

Fair_Values_of_Financial_Instr1

Fair Values of Financial Instruments (Tables)	6 Months Ended
Fair Values of Financial Instruments (Tables)	Jun. 30, 2014
Investments All Other Investments [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 June 30, 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
	June 30, 2014		Carrying Amount		Estimated		Level 1		Level 2		Level 3
	June 30, 2014		Carrying Amount		Fair Value		Inputs		Inputs		Inputs
	(in thousands)
	Financial assets:
	Securities held-to-maturity		$	1,536,988	$	1,537,839	$	—	$	1,537,839	$	—
	Loans (1)			1,292,503		1,269,530		—		—		1,269,530
	Financial liabilities:
	Time deposits			388,189		393,502		—		393,502		—
	Other borrowed funds			267,500		270,576		—		270,576		—
	Subordinated debentures			36,083		41,036		—		—		41,036

	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)	6 Months Ended
	Jun. 30, 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	6 Months Ended
	Nov. 02, 2009	Jun. 30, 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 $)	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Shares under option:	'	'
Outstanding at beginning of year, Amount	20,225	'
Exercised, Amount	-125	-1,600
Outstanding at end of period, Amount	20,100	'
Exercisable at end of period, Amount	20,100	'
Available to be granted at end of period, Amount	225,034	'
Outstanding at beginning of year, Weighted Average Exercise Price	$31.82	'
Exercised, Weighted Average Exercise Price	$31.83	'
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 $)	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Number of outstanding options	20,100	20,225
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	20,100	'
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	'3 months	'
Intrinsic value of options exercisable	$70,551	'
Intrinsic value of options exercised	$439	'

Securities_AvailableforSale_Su

Securities Available-for-Sale - Summary of Securities Available-for-Sale (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	$495,162	$465,943
Gross Unrealized Gains	1,295	821
Gross Unrealized Losses	2,148	2,519
Total, Fair Value	494,309	464,245
U.S. Treasury [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	1,998	1,997
Gross Unrealized Gains	3	1
Total, Fair Value	2,001	1,998
U.S. Government Sponsored Enterprises [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	'	9,995
Gross Unrealized Gains	'	9
Total, Fair Value	'	10,004
SBA Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	6,915	7,270
Gross Unrealized Gains	58	32
Total, Fair Value	6,973	7,302
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	419,732	404,103
Gross Unrealized Gains	1,039	588
Gross Unrealized Losses	1,146	1,501
Total, Fair Value	419,625	403,190
Privately Issued Residential Mortgage Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	2,122	2,294
Gross Unrealized Gains	16	6
Gross Unrealized Losses	11	23
Total, Fair Value	2,127	2,277
Obligations Issued by States and Political Subdivisions [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	61,768	37,578
Gross Unrealized Gains	5	15
Gross Unrealized Losses	871	870
Total, Fair Value	60,902	36,723
Other Debt Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	2,300	2,300
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	327	406
Gross Unrealized Gains	174	170
Total, Fair Value	$501	$576

Securities_AvailableforSale_Ad

Securities Available-for-Sale - Additional Information (Detail) (USD $)	0 Months Ended	3 Months Ended		6 Months Ended			6 Months Ended
	Jun. 30, 2014	Sep. 30, 2013	Jun. 30, 2013	Jun. 30, 2013	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014	Dec. 31, 2013
					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]	Securities AFS [Member]	Securities AFS [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	'	'	'	'	346,459,000	368,137,000	'	'	'	'
Securities available-for-sale are securities pledged for borrowing	'	'	'	'	'	'	34,242,000	12,214,000	'	'
Realized gains on sales of investments	'	'	'	'	'	'	0	'	'	'
Realized gross gain	'	'	781,000	1,664,000	'	'	'	'	'	'
Proceeds from sales of securities available-for-sale	'	'	'	$163,593,000	'	'	'	'	'	'
Weighted average remaining life of investment securities available-for-sale	'4 years 7 months 6 days	'	'	'	'	'	'	'	'	'
Number of securities, temporarily impaired for less than 12 months	'	'	'	'	'	'	'	'	27	20
Number of securities, temporarily impaired for 12 months or longer	'	'	'	'	'	'	'	'	14	7
Number of securities, temporarily impaired, total	'	'	'	'	'	'	'	'	254	458

Securities_AvailableforSale_Ma

Securities Available-for-Sale - Maturity Distribution of Securities Available-for-Sale (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Investments Debt And Equity Securities [Abstract]	'	'
Within one year, Amortized Cost	$55,709	'
After one but within five years, Amortized Cost	239,010	'
After five but within ten years, Amortized Cost	189,203	'
More than 10 years, Amortized Cost	9,413	'
Non-maturing, Amortized Cost	1,827	'
Total, Amortized Cost	495,162	465,943
Within one year, Fair Value	55,728	'
After one but within five years, Fair Value	239,068	'
After five but within ten years, Fair Value	188,968	'
More than 10 years, Fair Value	8,664	'
Non-maturing, Fair Value	1,881	'
Total, Fair Value	$494,309	$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 $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than 12 months, Fair Value	$166,346	$291,195
Less than 12 months, Unrealized Losses	764	1,375
12 months or longer, Fair Value	72,798	29,753
12 months or longer, Unrealized Losses	1,384	1,144
Total, Fair Value	239,144	320,948
Total, Unrealized Losses	2,148	2,519
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than 12 months, Fair Value	166,346	289,709
Less than 12 months, Unrealized Losses	764	1,352
12 months or longer, Fair Value	66,805	24,557
12 months or longer, Unrealized Losses	382	149
Total, Fair Value	233,151	314,266
Total, Unrealized Losses	1,146	1,501
Privately Issued Residential Mortgage Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than 12 months, Fair Value	'	1,486
Less than 12 months, Unrealized Losses	'	23
12 months or longer, Fair Value	793	'
12 months or longer, Unrealized Losses	11	'
Total, Fair Value	793	1,486
Total, Unrealized Losses	11	23
Obligations Issued by States and Political Subdivisions [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
12 months or longer, Fair Value	3,820	3,820
12 months or longer, Unrealized Losses	871	870
Total, Fair Value	3,820	3,820
Total, Unrealized Losses	871	870
Other Debt Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
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 $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	$1,536,988	$1,487,884
Gross Unrealized Gains	11,537	2,424
Gross Unrealized Losses	10,686	25,859
Estimated Fair Value	1,537,839	1,464,449
U.S. Government Sponsored Enterprises [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	328,351	291,779
Gross Unrealized Gains	2,021	185
Gross Unrealized Losses	633	5,043
Estimated Fair Value	329,739	286,921
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	1,208,637	1,196,105
Gross Unrealized Gains	9,516	2,239
Gross Unrealized Losses	10,053	20,816
Estimated Fair Value	$1,208,100	$1,177,528

Investment_Securities_HeldtoMa3

Investment Securities Held-to-Maturity - Additional Information (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Schedule of Held-to-maturity Securities [Line Items]	'	'
Securities pledged for borrowing at the Federal Home Loan Bank of Boston	$1,537,839,000	$1,464,449,000
Weighted average remaining life of investment securities held-to-maturity	'4 years 9 months 18 days	'
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	494,453,000	510,060,000
Held-to-Maturity Securities [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Number of securities, temporarily impaired for less than 12 months	43	3
Number of securities, temporarily impaired for 12 months or longer	57	1
Number of securities, temporarily impaired, total	310	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	746,339,000	732,144,000
Securities pledged for borrowing at the Federal Home Loan Bank of Boston	329,739,000	286,921,000
Weighted average remaining life	$260,065,000	'

Investment_Securities_HeldtoMa4

Investment Securities Held-to-Maturity - Company's Securities Held-to-Maturity (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Investments Debt And Equity Securities [Abstract]	'	'
Within one year, Amortized Cost	$4,464	'
After one but within five years, Amortized Cost	1,042,137	'
After five but within ten years, Amortized Cost	489,585	'
More than ten years, Amortized Cost	802	'
Total, Amortized Cost	1,536,988	1,487,884
Within one year, Fair Value	4,512	'
After one but within five years, Fair Value	1,042,271	'
After five but within ten years, Fair Value	490,234	'
More than ten years, Fair Value	822	'
Estimated Fair Value	$1,537,839	$1,464,449

Investment_Securities_HeldtoMa5

Investment Securities Held-to-Maturity - Unrealized Market Loss of Securities (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Held-to-maturity Securities [Line Items]	'	'
Less Than 12 Months, Fair Value	$283,934	$1,163,715
Less Than 12 Months, Unrealized Losses	2,411	23,697
12 Months or Longer, Fair Value	405,448	80,362
12 Months or Longer, Unrealized Losses	8,275	2,162
Total, Fair Value	689,382	1,244,077
Total, Unrealized Losses	10,686	25,859
U.S. Government Sponsored Enterprises [Member]	'	'
Schedule of Held-to-maturity Securities [Line Items]	'	'
Less Than 12 Months, Fair Value	61,736	232,535
Less Than 12 Months, Unrealized Losses	232	5,043
12 Months or Longer, Fair Value	29,161	'
12 Months or Longer, Unrealized Losses	401	'
Total, Fair Value	90,897	232,535
Total, Unrealized Losses	633	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	222,198	931,180
Less Than 12 Months, Unrealized Losses	2,179	18,654
12 Months or Longer, Fair Value	376,287	80,362
12 Months or Longer, Unrealized Losses	7,874	2,162
Total, Fair Value	598,485	1,011,542
Total, Unrealized Losses	$10,053	$20,816

Allowance_for_Loan_Losses_Summ

Allowance for Loan Losses - Summary of Changes in Allowance for Loan Losses (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Receivables [Abstract]	'	'	'	'
Allowance for loan losses, beginning of period	$21,259	$19,759	$20,941	$19,197
Loans charged off	-113	-160	-542	-533
Recoveries on loans previously charged-off	126	151	273	336
Net charge-offs	13	-9	-269	-197
Provision charged to expense	450	750	1,050	1,500
Allowance for loan losses, end of period	$21,722	$20,500	$21,722	$20,500

Allowance_for_Loan_Losses_Summ1

Allowance for Loan Losses - Summary of Allowance for Loan Losses (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Allowance for loan losses:	'	'	'	'	'
Allowance for loan losses, beginning of period	$21,259	$19,759	$20,941	$19,197	'
Charge-offs	-113	-160	-542	-533	'
Recoveries	126	151	273	336	'
Provision	450	750	1,050	1,500	'
Allowance for loan losses, end of period	21,722	20,500	21,722	20,500	'
Amount of allowance for loan losses for loans deemed to be impaired	1,238	1,539	1,238	1,539	'
Amount of allowance for loan losses for loans not deemed to be impaired	20,484	18,961	20,484	18,961	'
Loans:	'	'	'	'	'
Total loans, net	1,314,225	1,163,732	1,314,225	1,163,732	1,264,763
Loans deemed to be impaired	7,876	6,234	7,876	6,234	'
Loans not deemed to be impaired	1,306,349	1,157,498	1,306,349	1,157,498	'
Construction and Land Development [Member]	'	'	'	'	'
Allowance for loan losses:	'	'	'	'	'
Allowance for loan losses, beginning of period	1,825	3,199	2,174	3,041	'
Charge-offs	'	'	-250	'	'
Provision	220	42	121	200	'
Allowance for loan losses, end of period	2,045	3,241	2,045	3,241	'
Amount of allowance for loan losses for loans deemed to be impaired	273	1,000	273	1,000	'
Amount of allowance for loan losses for loans not deemed to be impaired	1,772	2,241	1,772	2,241	'
Loans:	'	'	'	'	'
Total loans, net	25,861	34,919	25,861	34,919	33,058
Loans deemed to be impaired	356	1,500	356	1,500	'
Loans not deemed to be impaired	25,505	33,419	25,505	33,419	'
Commercial and Industrial [Member]	'	'	'	'	'
Allowance for loan losses:	'	'	'	'	'
Allowance for loan losses, beginning of period	3,090	3,523	2,989	3,118	'
Charge-offs	-14	-6	-14	-234	'
Recoveries	24	56	48	121	'
Provision	-185	-358	-108	210	'
Allowance for loan losses, end of period	2,915	3,215	2,915	3,215	'
Amount of allowance for loan losses for loans deemed to be impaired	353	92	353	92	'
Amount of allowance for loan losses for loans not deemed to be impaired	2,562	3,123	2,562	3,123	'
Loans:	'	'	'	'	'
Total loans, net	88,666	101,918	88,666	101,918	92,402
Loans deemed to be impaired	1,093	1,102	1,093	1,102	'
Loans not deemed to be impaired	87,573	100,816	87,573	100,816	'
Commercial Real Estate [Member]	'	'	'	'	'
Allowance for loan losses:	'	'	'	'	'
Allowance for loan losses, beginning of period	11,874	8,779	11,218	9,065	'
Recoveries	2	1	4	4	'
Provision	99	644	753	355	'
Allowance for loan losses, end of period	11,975	9,424	11,975	9,424	'
Amount of allowance for loan losses for loans deemed to be impaired	359	204	359	204	'
Amount of allowance for loan losses for loans not deemed to be impaired	11,616	9,220	11,616	9,220	'
Loans:	'	'	'	'	'
Total loans, net	766,965	609,462	766,965	609,462	713,327
Loans deemed to be impaired	4,775	2,365	4,775	2,365	'
Loans not deemed to be impaired	762,190	607,097	762,190	607,097	'
Residential Real Estate [Member]	'	'	'	'	'
Allowance for loan losses:	'	'	'	'	'
Allowance for loan losses, beginning of period	1,873	2,071	2,006	1,994	'
Recoveries	15	1	20	4	'
Provision	39	-42	-99	32	'
Allowance for loan losses, end of period	1,927	2,030	1,927	2,030	'
Amount of allowance for loan losses for loans deemed to be impaired	160	147	160	147	'
Amount of allowance for loan losses for loans not deemed to be impaired	1,767	1,883	1,767	1,883	'
Loans:	'	'	'	'	'
Total loans, net	282,468	283,392	282,468	283,392	286,041
Loans deemed to be impaired	1,559	1,171	1,559	1,171	'
Loans not deemed to be impaired	280,909	282,221	280,909	282,221	'
Consumer [Member]	'	'	'	'	'
Allowance for loan losses:	'	'	'	'	'
Allowance for loan losses, beginning of period	425	357	432	333	'
Charge-offs	-99	-154	-278	-299	'
Recoveries	84	92	200	206	'
Provision	18	68	74	123	'
Allowance for loan losses, end of period	428	363	428	363	'
Amount of allowance for loan losses for loans not deemed to be impaired	428	363	428	363	'
Loans:	'	'	'	'	'
Total loans, net	9,649	8,123	9,649	8,123	9,658
Loans not deemed to be impaired	9,649	8,123	9,649	8,123	'
Home Equity [Member]	'	'	'	'	'
Allowance for loan losses:	'	'	'	'	'
Allowance for loan losses, beginning of period	902	833	959	886	'
Recoveries	1	1	1	1	'
Provision	12	98	-45	45	'
Allowance for loan losses, end of period	915	932	915	932	'
Amount of allowance for loan losses for loans deemed to be impaired	93	96	93	96	'
Amount of allowance for loan losses for loans not deemed to be impaired	822	836	822	836	'
Loans:	'	'	'	'	'
Total loans, net	140,616	125,918	140,616	125,918	130,277
Loans deemed to be impaired	93	96	93	96	'
Loans not deemed to be impaired	140,523	125,822	140,523	125,822	'
Unallocated [Member]	'	'	'	'	'
Allowance for loan losses:	'	'	'	'	'
Allowance for loan losses, beginning of period	1,270	997	1,163	760	'
Provision	247	298	354	535	'
Allowance for loan losses, end of period	1,517	1,295	1,517	1,295	'
Amount of allowance for loan losses for loans not deemed to be impaired	$1,517	$1,295	$1,517	$1,295	'

Allowance_for_Loan_Losses_Loan

Allowance for Loan Losses - Loans by Risk Rating (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
Loans by risk rating	'	'	'
Financing Receivable, Net	$1,314,225	$1,264,763	$1,163,732
Construction and Land Development [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	25,861	33,058	34,919
Construction and Land Development [Member] \| 1-3 (Pass) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	18,283	25,138	'
Construction and Land Development [Member] \| 4 (Monitor) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	7,222	7,312	'
Construction and Land Development [Member] \| Impaired [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	356	608	'
Commercial and Industrial [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	88,666	92,402	101,918
Commercial and Industrial [Member] \| 1-3 (Pass) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	87,101	90,563	'
Commercial and Industrial [Member] \| 4 (Monitor) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	472	472	'
Commercial and Industrial [Member] \| Impaired [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	1,093	1,367	'
Commercial Real Estate [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	766,965	713,327	609,462
Commercial Real Estate [Member] \| 1-3 (Pass) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	761,273	707,461	'
Commercial Real Estate [Member] \| 4 (Monitor) [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	917	1,346	'
Commercial Real Estate [Member] \| Impaired [Member]	'	'	'
Loans by risk rating	'	'	'
Financing Receivable, Net	$4,775	$4,520	'

Allowance_for_Loan_Losses_Agin

Allowance for Loan Losses - Aging of Past Due Loan Losses (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Accruing 30-89 Days Past Due	$5,102	$5,561	'
Non Accrual	2,845	2,549	'
Accrual Greater Than 90 Days	614	'	'
Total Past Due	8,561	8,110	'
Current Loans	1,305,664	1,256,653	'
Total loans, net	1,314,225	1,264,763	1,163,732
Construction and Land Development [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Non Accrual	356	500	'
Total Past Due	356	500	'
Current Loans	25,505	32,558	'
Total loans, net	25,861	33,058	34,919
Commercial and Industrial [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Accruing 30-89 Days Past Due	1,051	112	'
Non Accrual	450	706	'
Total Past Due	1,501	818	'
Current Loans	87,165	91,584	'
Total loans, net	88,666	92,402	101,918
Commercial Real Estate [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Accruing 30-89 Days Past Due	2,570	1,496	'
Non Accrual	610	306	'
Accrual Greater Than 90 Days	614	'	'
Total Past Due	3,794	1,802	'
Current Loans	763,171	711,525	'
Total loans, net	766,965	713,327	609,462
Residential Real Estate [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Accruing 30-89 Days Past Due	1,154	2,232	'
Non Accrual	1,426	1,034	'
Total Past Due	2,580	3,266	'
Current Loans	279,888	282,775	'
Total loans, net	282,468	286,041	283,392
Consumer [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Accruing 30-89 Days Past Due	1	11	'
Non Accrual	3	3	'
Total Past Due	4	14	'
Current Loans	9,645	9,644	'
Total loans, net	9,649	9,658	8,123
Home Equity [Member]	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'
Accruing 30-89 Days Past Due	326	1,710	'
Total Past Due	326	1,710	'
Current Loans	140,290	128,567	'
Total loans, net	$140,616	$130,277	$125,918

Allowance_for_Loan_Losses_Info

Allowance for Loan Losses - Information Pertaining to Impaired Loans (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'	'
With no required reserve recorded, Carrying Value	$481	$594	$481	$594
With no required reserve recorded, Unpaid Balance Principal	512	623	512	623
With no required reserve recorded, Required Reserve	'	'	'	'
With no required reserve recorded, Average Carrying Value	330	644	576	683
With no required reserve recorded, Interest Income Recognized	'	1	'	1
With required reserve recorded, Carrying Value	7,395	5,640	7,395	5,640
With required reserve recorded, Unpaid Balance Principal	10,975	7,837	10,975	7,837
With required reserve recorded, Required Reserve	1,238	1,539	1,238	1,539
With required reserve recorded, Average Carrying Value	6,855	5,540	6,785	5,429
With required reserve recorded, Interest Income Recognized	47	28	98	63
Carrying Value	7,876	6,234	7,876	6,234
Unpaid Principal Balance	11,487	8,460	11,487	8,460
With required reserve recorded, Required Reserve	1,238	1,539	1,238	1,539
Average Carrying Value	7,185	6,184	7,362	6,112
Interest Income Recognized	47	29	98	64
Construction and Land Development [Member]	'	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'	'
With no required reserve recorded, Required Reserve	'	'	'	'
With no required reserve recorded, Average Carrying Value	188	'	321	'
With required reserve recorded, Carrying Value	356	1,500	356	1,500
With required reserve recorded, Unpaid Balance Principal	3,400	3,292	3,400	3,292
With required reserve recorded, Required Reserve	273	1,000	273	1,000
With required reserve recorded, Average Carrying Value	169	1,500	143	1,500
Carrying Value	356	1,500	356	1,500
Unpaid Principal Balance	3,400	3,292	3,400	3,292
With required reserve recorded, Required Reserve	273	1,000	273	1,000
Average Carrying Value	357	1,500	465	1,500
Commercial and Industrial [Member]	'	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'	'
With no required reserve recorded, Carrying Value	11	206	11	206
With no required reserve recorded, Unpaid Balance Principal	42	235	42	235
With no required reserve recorded, Required Reserve	'	'	'	'
With no required reserve recorded, Average Carrying Value	11	385	71	451
With no required reserve recorded, Interest Income Recognized	'	1	'	1
With required reserve recorded, Carrying Value	1,082	896	1,082	896
With required reserve recorded, Unpaid Balance Principal	1,332	1,128	1,332	1,128
With required reserve recorded, Required Reserve	353	92	353	92
With required reserve recorded, Average Carrying Value	1,095	866	1,104	856
With required reserve recorded, Interest Income Recognized	8	8	19	17
Carrying Value	1,093	1,102	1,093	1,102
Unpaid Principal Balance	1,374	1,363	1,374	1,363
With required reserve recorded, Required Reserve	353	92	353	92
Average Carrying Value	1,106	1,251	1,175	1,307
Interest Income Recognized	8	9	19	18
Commercial Real Estate [Member]	'	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'	'
With no required reserve recorded, Carrying Value	400	122	400	122
With no required reserve recorded, Unpaid Balance Principal	400	122	400	122
With no required reserve recorded, Required Reserve	'	'	'	'
With no required reserve recorded, Average Carrying Value	100	113	80	136
With required reserve recorded, Carrying Value	4,375	2,243	4,375	2,243
With required reserve recorded, Unpaid Balance Principal	4,466	2,330	4,466	2,330
With required reserve recorded, Required Reserve	359	204	359	204
With required reserve recorded, Average Carrying Value	4,391	2,169	4,405	2,143
With required reserve recorded, Interest Income Recognized	36	20	74	46
Carrying Value	4,775	2,365	4,775	2,365
Unpaid Principal Balance	4,866	2,452	4,866	2,452
With required reserve recorded, Required Reserve	359	204	359	204
Average Carrying Value	4,491	2,282	4,485	2,279
Interest Income Recognized	36	20	74	46
Residential Real Estate [Member]	'	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'	'
With no required reserve recorded, Carrying Value	70	266	70	266
With no required reserve recorded, Unpaid Balance Principal	70	266	70	266
With no required reserve recorded, Required Reserve	'	'	'	'
With no required reserve recorded, Average Carrying Value	31	146	104	96
With required reserve recorded, Carrying Value	1,489	905	1,489	905
With required reserve recorded, Unpaid Balance Principal	1,684	991	1,684	991
With required reserve recorded, Required Reserve	160	147	160	147
With required reserve recorded, Average Carrying Value	1,106	909	1,039	834
With required reserve recorded, Interest Income Recognized	3	'	5	'
Carrying Value	1,559	1,171	1,559	1,171
Unpaid Principal Balance	1,754	1,257	1,754	1,257
With required reserve recorded, Required Reserve	160	147	160	147
Average Carrying Value	1,137	1,055	1,143	930
Interest Income Recognized	3	'	5	'
Consumer [Member]	'	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'	'
With no required reserve recorded, Required Reserve	'	'	'	'
Home Equity [Member]	'	'	'	'
Financing Receivable, Allowance for Credit Losses [Line Items]	'	'	'	'
With no required reserve recorded, Required Reserve	'	'	'	'
With required reserve recorded, Carrying Value	93	96	93	96
With required reserve recorded, Unpaid Balance Principal	93	96	93	96
With required reserve recorded, Required Reserve	93	96	93	96
With required reserve recorded, Average Carrying Value	94	96	94	96
Carrying Value	93	96	93	96
Unpaid Principal Balance	93	96	93	96
With required reserve recorded, Required Reserve	93	96	93	96
Average Carrying Value	$94	$96	$94	$96

Allowance_for_Loan_Losses_Addi

Allowance for Loan Losses - Additional Information (Detail) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 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		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Net gains on sales of investments	'	$781	'	$1,664
Securities held-to-maturity	8,020	1,419	15,800	2,939
Provision for income taxes	-231	-295	-524	-583
Net income	5,599	5,026	10,531	9,502
Salaries and employee benefits	-8,776	-8,382	-17,651	-17,000
Reclassification Out of Accumulated Other Comprehensive Income [Member]	'	'	'	'
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]	'	'	'	'
Net income	752	305	1,619	665
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	'	781	'	1,664
Provision for income taxes	'	-302	'	-652
Net income	'	479	'	1,012
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	1,286	'	2,793	'
Provision for income taxes	-478	'	-1,061	'
Net income	808	'	1,732	'
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	-5	-6
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	-91	-287	-183	-574
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	-94	-290	-188	-580
Provision for income taxes	38	116	75	233
Net income	($56)	($174)	($113)	($347)

Earnings_Per_Share_EPS_Additio

Earnings Per Share ("EPS") - Additional Information (Detail) (Class A Common Stock [Member])	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]	'	'	'	'
Dilutive effect of stock options, increment in shares	1,327	795	1,452	1,162
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		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]	'	'	'	'
Net income	$5,599	$5,026	$10,531	$9,502
Class A Common Stock [Member]	'	'	'	'
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]	'	'	'	'
Net income	4,394	3,935	8,259	7,437
Weighted average shares outstanding, basic	3,589,125	3,574,379	3,585,773	3,571,963
Basic earnings per share	$1.22	$1.10	$2.30	$2.08
Dilutive effect of Class A stock options	1,327	795	1,452	1,162
Weighted average shares outstanding, diluted	5,558,032	5,557,354	5,558,105	5,557,655
Diluted earnings per share	$1.01	$0.90	$1.89	$1.71
Class B Common Stock [Member]	'	'	'	'
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]	'	'	'	'
Net income	$1,205	$1,091	$2,272	$2,065
Weighted average shares outstanding, basic	1,967,580	1,982,180	1,970,880	1,984,530
Basic earnings per share	$0.61	$0.55	$1.15	$1.04
Weighted average shares outstanding, diluted	1,967,580	1,982,180	1,970,880	1,984,530
Diluted earnings per share	$0.61	$0.55	$1.15	$1.04

Employee_Benefits_Additional_I

Employee Benefits - Additional Information (Detail) (USD $)	6 Months Ended
Employee Benefits - Additional Information (Detail) (USD $)	Jun. 30, 2014
Compensation And Retirement Disclosure [Abstract]	'
Number of years service to participate in supplemental plan	'1 year
Current fiscal year contribution to pension plan	$920,000
Additional contributions to pension plan in remainder of current fiscal year	$0

Employee_Benefits_Components_o

Employee Benefits - Components of Net Periodic Benefit Cost (Credit) (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Pension Benefits [Member]	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	$258	$299	$516	$598
Interest	367	314	734	628
Expected return on plan assets	-636	-470	-1,272	-940
Recognized prior service cost (benefit)	-26	-26	-52	-52
Recognized net actuarial losses	3	158	6	316
Net periodic benefit (credit) cost	-34	275	-68	550
Supplemental Insurance/ Retirement Plan [Member]	'	'	'	'
Defined Benefit Plan Disclosure [Line Items]	'	'	'	'
Service cost	389	381	778	763
Interest	331	267	662	534
Recognized prior service cost (benefit)	29	29	58	58
Recognized net actuarial losses	88	129	176	258
Net periodic benefit (credit) cost	$837	$806	$1,674	$1,613

Fair_Value_Measurements_Financ

Fair Value Measurements - Financial Instruments Measured at Fair Value on a Recurring and Non-recurring Basis (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	$494,309	$464,245
Fair Value Measurements, Level 1 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	290	'
Fair Value Measurements, Level 2 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	433,314	'
Fair Value Measurements, Level 3 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	60,705	'
U.S. Treasury [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	2,001	1,998
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	2,001	'
SBA Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	6,973	7,302
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	6,973	'
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	419,625	403,190
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	419,625	'
Privately Issued Residential Mortgage Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	2,127	2,277
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	2,127	'
Obligations Issued by States and Political Subdivisions [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	60,902	36,723
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	408	'
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	60,494	'
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 2 Inputs [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	2,180	'
Equity Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	501	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	290	'
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	211	'
Impaired Loans [Member] \| Fair Value Measurements, Level 3 Inputs [Member]	'	'
Financial Instruments Measured at Fair Value on a Non-recurring Basis	'	'
Impaired Loans	2,539	'
Carrying Value [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	494,309	'
Carrying Value [Member] \| U.S. Treasury [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	2,001	'
Carrying Value [Member] \| SBA Backed Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities AFS	6,973	'
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	419,625	'
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	2,127	'
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	60,902	'
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	501	'
Carrying Value [Member] \| Impaired Loans [Member]	'	'
Financial Instruments Measured at Fair Value on a Non-recurring Basis	'	'
Impaired Loans	$2,539	'

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2013
	Jun. 30, 2014	Jun. 30, 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	$276,000	$530,000	'	'
Transfers between level 1 and 2	0	0	'	'
Liabilities measured at fair value on a recurring or nonrecurring basis	0	0	'	'
Amortized cost of Level 3 securities	'	'	61,577,000	53,018,000
Unrealized loss	'	'	$872,000	$724,000

Fair_Value_Measurements_Assets

Fair Value Measurements - Assets Measured at Fair Value (Detail) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014
Securities AFS [Member]	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'
Fair Value	$60,705
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	$2,539
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_Assets1

Fair Value Measurements - Assets Measured at Fair Value (Parenthetical) (Detail) (Municipal Notes [Member])	6 Months Ended
	Jun. 30, 2014
Municipal Notes [Member]	'
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]	'
Securities maturity period	'one year or less

Fair_Value_Measurements_Change

Fair Value Measurements - Changes in Level 3 Securities (Detail) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'	'
Beginning Balance	$36,597	$53,782
Purchases	51,471	29,370
Maturities and calls	-27,361	-30,840
Amortization	-2	-18
Changes in fair value	'	'
Ending Balance	60,705	52,294
Auction Rate Securities [Member]	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'	'
Beginning Balance	3,820	3,963
Changes in fair value	'	'
Ending Balance	3,820	3,963
Obligations Issued by States and Political Subdivisions [Member]	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'	'
Beginning Balance	32,487	49,477
Purchases	51,471	29,370
Maturities and calls	-27,282	-30,830
Amortization	-2	-18
Changes in fair value	'	'
Ending Balance	56,674	47,999
Equity Securities [Member]	'	'
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]	'	'
Beginning Balance	290	342
Maturities and calls	-79	-10
Changes in fair value	'	'
Ending Balance	$211	$332

Fair_Values_of_Financial_Instr2

Fair Values of Financial Instruments - Carrying Amount and Fair Value of Company's Financial Instruments (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financial assets:	'	'
Securities held-to-maturity	$1,536,988	$1,487,884
Loans	1,292,503	1,243,822
Financial liabilities:	'	'
Time deposits	388,189	382,224
Other borrowed funds	267,500	255,144
Subordinated debentures	36,083	36,083
Carrying Value [Member]	'	'
Financial assets:	'	'
Securities held-to-maturity	1,536,988	1,487,884
Loans	1,292,503	1,243,822
Financial liabilities:	'	'
Time deposits	388,189	382,224
Other borrowed funds	267,500	255,144
Subordinated debentures	36,083	36,083
Estimated Fair Value [Member]	'	'
Financial assets:	'	'
Securities held-to-maturity	1,537,839	1,464,449
Loans	1,269,530	1,214,192
Financial liabilities:	'	'
Time deposits	393,502	386,742
Other borrowed funds	270,576	254,736
Subordinated debentures	41,036	39,503
Fair Value Measurements, Level 2 Inputs [Member]	'	'
Financial assets:	'	'
Securities held-to-maturity	1,537,839	1,464,449
Financial liabilities:	'	'
Time deposits	393,502	386,742
Other borrowed funds	270,576	254,736
Fair Value Measurements, Level 3 Inputs [Member]	'	'
Financial assets:	'	'
Loans	1,269,530	1,214,192
Financial liabilities:	'	'
Subordinated debentures	$41,036	$39,503