Century Bancorp (CNBKA) 10-Q 10 May 16 2016 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2016	Apr. 30, 2016
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1
Trading Symbol	CNBKA
Entity Registrant Name	CENTURY BANCORP INC
Entity Central Index Key	812,348
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Class A Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		3,600,729
Class B Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		1,967,180

Consolidated Balance Sheets (un

Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Assets
Cash and due from banks	$ 71,655	$ 52,877
Federal funds sold and interest-bearing deposits in other banks	232,995	167,847
Total cash and cash equivalents	304,650	220,724
Short-term investments	3,241	3,233
Securities available-for-sale, amortized cost $380,219 and $404,977, respectively	380,349	404,623
Securities held-to-maturity, fair value $1,437,205 and $1,438,960, respectively	1,412,702	1,438,903
Federal Home Loan Bank of Boston stock, at cost	23,909	28,807
Loans Held-for-Sale	48,180
Loans, net:
Commercial and industrial	529,168	452,235
Municipal	85,227	85,685
Construction and land development	26,572	27,421
Commercial real estate	715,248	721,506
Residential real estate	215,040	255,346
Home equity	178,377	178,020
Consumer and other	12,826	11,323
Total loans, net	1,762,458	1,731,536
Less: allowance for loan losses	23,544	23,075
Net loans	1,738,914	1,708,461
Bank premises and equipment	23,797	24,106
Accrued interest receivable	7,524	8,002
Goodwill	2,714	2,714
Other assets	108,817	107,868
Total assets	4,054,797	3,947,441
Deposits:
Demand deposits	577,842	541,955
Savings and NOW deposits	1,197,257	1,070,585
Money market accounts	944,621	989,094
Time deposits	446,185	473,426
Total deposits	3,165,905	3,075,060
Securities sold under agreements to repurchase	218,230	197,850
Other borrowed funds	356,000	368,000
Subordinated debentures	36,083	36,083
Due to broker	1,741	405
Other liabilities	55,997	55,499
Total liabilities	$ 3,833,956	$ 3,732,897
Stockholders' Equity
Preferred stock - $1.00 par value; 100,000 shares authorized; no shares issued and outstanding
Additional paid-in capital	$ 12,292	$ 12,292
Retained earnings	225,989	221,232
Stockholders' equity before adjustment of accumulated other comprehensive income (loss)	243,849	239,092
Unrealized gains (losses) on securities available-for-sale, net of taxes	68	(246)
Unrealized losses on securities transferred to held-to-maturity, net of taxes	(5,912)	(6,896)
Pension liability, net of taxes	(17,164)	(17,406)
Total accumulated other comprehensive loss, net of taxes	(23,008)	(24,548)
Total stockholders' equity	220,841	214,544
Total liabilities and stockholders' equity	4,054,797	3,947,441
Class A Common Stock [Member]
Stockholders' Equity
Common stock value	3,601	3,601
Total stockholders' equity	3,601	3,601
Class B Common Stock [Member]
Stockholders' Equity
Common stock value	1,967	1,967
Total stockholders' equity	$ 1,967	$ 1,967

Consolidated Balance Sheets (u3

Consolidated Balance Sheets (unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Amortized cost	$ 380,219	$ 404,977
Held-to-maturity securities, fair value	$ 1,437,205	$ 1,438,960
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	3,600,729	3,600,729
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	1,967,180	1,976,180

Consolidated Statements of Inco

Consolidated Statements of Income (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Interest income
Loans	$ 14,172	$ 12,076
Securities held-to-maturity	7,812	8,168
Securities available-for-sale	964	732
Federal funds sold and interest-bearing deposits in other banks	315	196
Total interest income	23,263	21,172
Interest expense
Savings and NOW deposits	838	628
Money market accounts	795	782
Time deposits	1,358	1,156
Securities sold under agreements to repurchase	115	114
Other borrowed funds and subordinated debentures	2,307	2,085
Total interest expense	5,413	4,765
Net interest income	17,850	16,407
Provision for loan losses	450	200
Net interest income after provision for loan losses	17,400	16,207
Other operating income
Service charges on deposit accounts	1,937	1,913
Lockbox fees	789	788
Gains on sales of mortgage loans		99
Other income	928	705
Total other operating income	3,654	3,505
Operating expenses
Salaries and employee benefits	9,776	9,134
Occupancy	1,579	1,605
Equipment	636	593
FDIC assessments	568	503
Other	3,124	2,703
Total operating expenses	15,683	14,538
Income before income taxes	5,371	5,174
Provision for income taxes	64	215
Net income	5,307	4,959
Class A Common Stock [Member]
Operating expenses
Net income	$ 4,168	$ 3,895
Share data:
Weighted average number of shares outstanding, basic	3,600,729	3,600,729
Weighted average number of shares outstanding, diluted	5,567,909	5,567,909
Basic earnings per share	$ 1.16	$ 1.08
Diluted earnings per share	$ 0.95	$ 0.89
Class B Common Stock [Member]
Operating expenses
Net income	$ 1,139	$ 1,064
Share data:
Weighted average number of shares outstanding, basic	1,967,180	1,967,180
Weighted average number of shares outstanding, diluted	1,967,180	1,967,180
Basic earnings per share	$ 0.58	$ 0.54
Diluted earnings per share	$ 0.58	$ 0.54

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 5,307	$ 4,959
Unrealized gains (losses) on securities:
Unrealized (losses) gains arising during period	314	(30)
Less: reclassification adjustment for gains included in net income	0	0
Total unrealized (losses) gains on securities	314	(30)
Accretion of net unrealized losses transferred	984	735
Defined benefit pension plans:
Amortization of prior service cost and loss included in net periodic benefit cost	242	213
Other comprehensive income	1,540	918
Comprehensive income	$ 6,847	$ 5,877

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity (unaudited) - USD ($) $ in Thousands	Total	Class A Common Stock [Member]	Class B Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Retained Earnings [Member]Class A Common Stock [Member]	Retained Earnings [Member]Class B Common Stock [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning balance at Dec. 31, 2014	$ 192,500	$ 3,601	$ 1,967	$ 12,292	$ 200,411			$ (25,771)
Net income	4,959	3,895	1,064		4,959
Other comprehensive income, net of tax:
Unrealized holding (losses) gains arising during period, net of taxes	(30)							(30)
Accretion of unrealized losses on securities transferred to held-to-maturity net of taxes	735							735
Pension liability adjustment, net of taxes	213							213
Cash dividends	(432)					$ (432)	$ (117)
Ending balance at Mar. 31, 2015	197,828	3,601	1,967	12,292	204,821			(24,853)
Beginning balance at Dec. 31, 2015	214,544	3,601	1,967	12,292	221,232			(24,548)
Net income	5,307	4,168	1,139		5,307
Other comprehensive income, net of tax:
Unrealized holding (losses) gains arising during period, net of taxes	314							314
Accretion of unrealized losses on securities transferred to held-to-maturity net of taxes	984							984
Pension liability adjustment, net of taxes	242							242
Cash dividends	(433)					$ (433)	$ (117)
Ending balance at Mar. 31, 2016	$ 220,841	$ 3,601	$ 1,967	$ 12,292	$ 225,989			$ (23,008)

Consolidated Statements of Cha7

Consolidated Statements of Changes in Stockholders' Equity (unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Unrealized holding (losses) gains arising during period, taxes	$ 170	$ 19
Accretion of net unrealized losses transferred during the period, taxes	527	394
Pension liability adjustment, taxes	$ 161	$ 142
Class A Common Stock [Member]
Cash dividends, per share	$ 0.12	$ 0.12
Class B Common Stock [Member]
Cash dividends, per share	$ 0.06	$ 0.06

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 5,307	$ 4,959
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Gain on sales of mortgage loans		(99)
Provision for loan losses	450	200
Deferred income taxes	(1,098)	(175)
Net depreciation and amortization	729	696
Decrease (increase) in accrued interest receivable	478	(672)
Increase in other assets	(744)	(4,621)
Increase (decrease) in other liabilities	901	(904)
Net cash provided by (used in) operating activities	6,023	(616)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of short-term investments	(8)	(8)
Proceeds from redemptions of Federal Home Loan Bank of Boston stock	4,898
Proceeds from calls/maturities of securities available-for-sale	47,099	34,265
Purchase of securities available-for-sale	(21,095)	(34,767)
Proceeds from calls/maturities of securities held-to-maturity	113,454	50,467
Purchase of securities held-to-maturity	(85,654)	(416,137)
Net increase in loans	(79,070)	(14,903)
Proceeds from sales of portfolio loans		5,061
Capital expenditures	(396)	(621)
Net cash used in investing activities	(20,772)	(376,643)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net decrease in time deposits	(27,241)	(689)
Net increase in demand, savings, money market and NOW deposits	118,086	178,593
Cash dividends	(550)	(549)
Net increase in securities sold under agreements to repurchase	20,380	48,030
Net decrease in other borrowed funds	(12,000)	(87,858)
Net cash provided by financing activities	98,675	137,527
Net (decrease) increase in cash and cash equivalents	83,926	(239,732)
Cash and cash equivalents at beginning of period	220,724	305,357
Cash and cash equivalents at end of period	304,650	65,625
Cash paid during the period for:
Interest	5,405	4,668
Income taxes	210	210
Change in unrealized gains (losses) on securities available-for-sale, net of taxes	314	(30)
Change in unrealized losses on securities transferred to held-to-maturity, net of taxes	984	735
Pension liability adjustment, net of taxes	242	213
Change in due to (from) to broker	1,336	$ 7,142
Transfer of loans to Loans Held-for-Sale	$ 48,180

Basis of Financial Statement Pr

Basis of Financial Statement Presentation	3 Months Ended
	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [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, 2015, 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.

Securities Available-for-Sale

Securities Available-for-Sale	3 Months Ended
	Mar. 31, 2016
Text Block [Abstract]
Securities Available-for-Sale	Note 2. Securities Available-for-Sale March 31, 2016 December 31, 2015 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) U.S. Treasury $ 1,999 $ — $ 2 $ 1,997 $ 1,999 $ — $ 10 $ 1,989 U.S. Government Sponsored Enterprises 5,000 8 — 5,008 — — — — SBA Backed Securities 5,925 10 4 5,931 5,983 8 2 5,989 U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities 225,727 759 193 226,293 232,967 859 300 233,526 Privately Issued Residential Mortgage Backed Securities 1,362 2 19 1,345 1,437 10 13 1,434 Obligations Issued by States and Political Subdivisions 135,490 — 401 135,089 157,838 — 878 156,960 Other Debt Securities 4,600 — 131 4,469 4,600 3 130 4,473 Equity Securities 116 101 — 217 153 99 — 252 Total $ 380,219 $ 880 $ 750 $ 380,349 $ 404,977 $ 979 $ 1,333 $ 404,623 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 $213,639,000 and $220,482,000 at March 31, 2016 and December 31, 2015, respectively. Also included in securities available-for-sale are securities pledged for borrowing at the Federal Home Loan Bank of Boston amounting to $19,103,000 and $20,056,000 at March 31, 2016 and December 31, 2015, respectively. There were no realized gains on sales of investments for the three months ended March 31, 2016 and March 31, 2015, respectively. Debt securities of Government Sponsored Enterprises primarily refer to debt securities of Fannie Mae and Freddie Mac. The following table shows the maturity distribution of the Company’s securities available-for-sale at March 31, 2016. Amortized Cost Fair Value (in thousands) Within one year $ 129,038 $ 129,037 After one but within five years 160,638 161,034 After five but within ten years 83,228 83,391 More than 10 years 5,699 5,283 Non-maturing 1,616 1,604 Total $ 380,219 $ 380,349 The weighted average remaining life of investment securities available-for-sale at March 31, 2016 was 3.3 years. Included in the weighted average remaining life calculation at March 31, 2016 were $5,000,000 of U.S. Government Sponsored Enterprises obligations that are callable at the discretion of the issuer. The contractual maturities, which were used in the table above, of mortgage-backed securities, will differ from the actual maturities, due to the ability of the issuers to prepay underlying obligations. As of March 31, 2016 and December 31, 2015, 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 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. Treasury, SBA Backed Securities, and U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities, related primarily to interest rates and not credit quality and because the Company has the ability and intent to hold these investments until recovery of fair value, which may be maturity. The Company does not consider these investments to be other-than-temporarily impaired. In evaluating the underlying credit quality of a security, management considers several factors such as the credit rating of the obligor and the issuer, if applicable. Internal reviews of issuer financial statements are performed as deemed necessary. In the case of privately issued mortgage-backed securities, the performance of the underlying loans is analyzed as deemed necessary to determine the estimated future cash flows of the securities. Factors considered include the level of subordination, current and estimated future default rates, current and estimated prepayment rates, estimated loss severity rates, geographic concentrations and origination dates of underlying loans. In the case of marketable equity securities, the severity of the unrealized loss, the length of time the unrealized loss has existed, and the issuer’s financial performance are considered. The following table shows the temporarily impaired securities of the Company’s available-for-sale portfolio at March 31, 2016. 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 10 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 267 holdings at March 31, 2016. March 31, 2016 Less than 12 months 12 months or longer Total Temporarily Impaired Investments Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized (in thousands) U.S. Treasury $ — $ — $ 1,997 $ 2 $ 1,997 $ 2 Small Business Administration 1,799 4 — — 1,799 4 U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities 46,435 113 29,009 80 75,444 193 Privately Issued Residential Mortgage Backed Securities 429 2 471 17 900 19 Obligations Issued by States and Political Subdivisions — — 4,298 401 4,298 401 Other Debt Securities 1,184 17 1,685 114 2,869 131 Total temporarily impaired securities $ 49,847 $ 136 $ 37,460 $ 614 $ 87,307 $ 750 The following table shows the temporarily impaired securities of the Company’s available-for-sale portfolio at December 31, 2015. 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 14 and 11 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 290 holdings at December 31, 2015. December 31, 2015 Less than 12 months 12 months or longer Total Temporarily Impaired Investments Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized (in thousands) U.S. Treasury $ 1,989 $ 10 $ — $ — $ 1,989 $ 10 SBA Backed Securities 1,031 2 — — 1,031 2 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 26,519 52 49,341 248 75,860 300 Privately Issued Residential Mortgage-Backed Securities — — 490 13 490 13 Obligations Issued by States and Political Subdivisions — — 3,820 878 3,820 878 Other Debt Securities 497 3 1,373 127 1,870 130 $ 30,036 $ 67 $ 55,024 $ 1,266 $ 85,060 $ 1,333

Investment Securities Held-to-M

Investment Securities Held-to-Maturity	3 Months Ended
	Mar. 31, 2016
Text Block [Abstract]
Investment Securities Held-to-Maturity	Note 3. Investment Securities Held-to-Maturity March 31, 2016 December 31, 2015 Amortized Gross Gross Estimated Value Amortized Gross Gross Estimated (in thousands) U.S. Government Sponsored Enterprises $ 152,732 $ 3,033 $ 11 $ 155,754 $ 186,734 $ 2,234 $ 141 $ 188,827 U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities 1,259,970 22,843 1,362 1,281,451 1,252,169 7,547 9,583 1,250,133 Total $ 1,412,702 $ 25,876 $ 1,373 $ 1,437,205 $ 1,438,903 $ 9,781 $ 9,724 $ 1,438,960 Included in U.S. Government and Agency Securities are securities pledged to secure public deposits and repurchase agreements at fair value amounting to $1,001,953,000 and $1,004,743,000 at March 31, 2016 and December 31, 2015, respectively. Also included are securities pledged for borrowing at the Federal Home Loan Bank of Boston at fair value amounting to $368,956,000 and $432,965,000 at March 31, 2016 and December 31, 2015, respectively. At March 31, 2016 and December 31, 2015, all mortgage-backed securities are obligations of U.S. Government Agencies and Government Sponsored Enterprises. Government Sponsored Enterprises primarily refer to debt securities of Fannie Mae and Freddie Mac. The following table shows the maturity distribution of the Company’s securities held-to-maturity at March 31, 2016. Amortized Fair Value (in thousands) Within one year $ 9,242 $ 9,343 After one but within five years 1,205,411 1,223,805 After five but within ten years 193,283 199,272 More than ten years 4,766 4,785 Total $ 1,412,702 $ 1,437,205 The weighted average remaining life of investment securities held-to-maturity at March 31, 2016 was 3.9 years. Included in the weighted average remaining life calculation at March 31, 2016 were $54,658,000 of U.S. Government Sponsored Enterprises obligations that are callable at the discretion of the issuer. The actual maturities, which were used in the table above, of mortgage-backed securities, will differ from the contractual maturities, due to the ability of the issuers to prepay underlying obligations. As of March 31, 2016 and December 31, 2015, 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 Sponsored Enterprises and U.S. Government Agency and Sponsored Enterprises Mortgage-Backed Securities related primarily to interest rates and not credit quality, and because the Company does not intend to sell any of these securities and it is not likely that it will be required to sell these securities before the anticipated recovery of the remaining amortized cost, the Company does not consider these investments to be other-than-temporarily impaired at March 31, 2016 and December 31, 2015. In evaluating the underlying credit quality of a security, management considers several factors such as the credit rating of the obligor and the issuer, if applicable. Internal reviews of issuer financial statements are performed as deemed necessary. The following table shows the temporarily impaired securities of the Company’s held-to-maturity portfolio at March 31, 2016. 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 24 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 326 holdings at March 31, 2016. March 31, 2016 Less Than 12 Months 12 Months or Longer Total Temporarily Impaired Investments Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized (in thousands) U.S. Government Sponsored Enterprises $ 19,990 $ 11 $ — $ — $ 19,990 $ 11 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 91,770 379 120,167 983 211,937 1,362 Total temporarily impaired securities $ 111,760 $ 390 $ 120,167 $ 983 $ 231,927 $ 1,373 The following table shows the temporarily impaired securities of the Company’s held-to-maturity portfolio at December 31, 2015. 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 101 and 26 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 322 holdings at December 31, 2015. December 31, 2015 Less Than 12 Months 12 Months or Longer Total Temporarily Impaired Investments Fair Value Unrealized Fair Unrealized Fair Value Unrealized (in thousands) U.S. Government Sponsored Enterprises $ 9,859 $ 141 $ — $ — $ 9,859 $ 141 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 626,218 6,657 123,864 2,926 750,082 9,583 Total temporarily impaired securities $ 636,077 $ 6,798 $ 123,864 $ 2,926 $ 759,941 $ 9,724

Allowance for Loan Losses

Allowance for Loan Losses	3 Months Ended
	Mar. 31, 2016
Receivables [Abstract]
Allowance for Loan Losses	Note 4. 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, 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 2016 2015 (in thousands) Allowance for loan losses, beginning of period $ 23,075 $ 22,318 Loans charged off (69 ) (81 ) Recoveries on loans previously charged-off 88 92 Net recoveries (charge-offs) 19 11 Provision charged to expense 450 200 Allowance for loan losses, end of period $ 23,544 $ 22,529 Further information pertaining to the allowance for loan losses for the three months ending March 31, 2016 follows: Construction Commercial Municipal Commercial Estate Residential Consumer Home Unallocated Total (in thousands) Allowance for loan losses: Balance at $ 2,041 $ 5,899 $ 994 $ 10,589 $ 1,320 $ 644 $ 1,077 $ 511 $ 23,075 Charge-offs — — — — — (69 ) — — (69 ) Recoveries — 35 — — 2 51 — — 88 Provision (68 ) 759 (4 ) (56 ) (73 ) 67 108 (283 ) 450 Ending balance at March 31, 2016 $ 1,973 $ 6,693 $ 990 $ 10,533 $ 1,249 $ 693 $ 1,185 $ 228 $ 23,544 Amount of allowance for loan losses for loans deemed to be $ 7 $ 17 $ — $ 89 $ 27 $ — $ 89 $ — 229 Amount of allowance for loan losses for loans not deemed to be impaired $ 1,966 $ 6,676 $ 990 $ 10,444 $ 1,222 $ 693 $ 1,096 $ 228 $ 23,315 Loans: Ending balance $ 26,572 $ 529,168 $ 85,227 $ 715,248 $ 215,040 $ 12,826 $ 178,377 $ — $ 1,762,458 Loans deemed to be impaired $ 98 $ 429 $ — $ 1,665 $ 905 $ — $ 89 $ — $ 3,186 Loans not deemed to be impaired $ 26,474 $ 528,739 $ 85,227 $ 713,583 $ 214,135 $ 12,826 $ 178,288 $ — $ 1,759,272 Further information pertaining to the allowance for loan losses for the three months ending March 31, 2015 follows: Construction Commercial Municipal Commercial Residential Consumer Home Unallocated Total (in thousands) Allowance for loan losses: Balance at December 31, 2014 $ 1,592 $ 4,758 $ 1,488 $ 11,199 $ 775 $ 810 $ 599 $ 1,097 $ 22,318 Charge-offs — — — — — (81 ) — — (81 ) Recoveries — 15 — 2 2 73 — — 92 Provision 292 (128 ) (115 ) (74 ) 22 (88 ) 15 276 200 Ending balance at March 31, 2015 $ 1,884 $ 4,645 $ 1,373 $ 11,127 $ 799 $ 714 $ 614 $ 1,373 $ 22,529 Amount of allowance for loan losses for loans deemed to be impaired $ 20 $ 96 $ — $ 631 $ 90 $ — $ 92 $ — 929 Amount of allowance for loan losses for loans not deemed to be impaired $ 1,864 $ 4,549 $ 1,373 $ 10,496 $ 709 $ 714 $ 522 $ 1,373 $ 21,600 Loans: Ending balance $ 25,347 $ 157,637 $ 41,406 $ 691,811 $ 258,558 $ 10,508 $ 156,063 $ — $ 1,341,330 Loans deemed to be impaired $ 102 $ 871 $ — $ 4,304 $ 952 $ — $ 92 $ — $ 6,321 Loans not deemed to be impaired $ 25,245 $ 156,766 $ 41,406 $ 687,507 $ 257,606 $ 10,508 $ 155,971 $ — $ 1,335,009 The Company utilizes a six grade internal loan rating system for commercial real estate, construction and commercial loans as follows: Loans rated 1-3 (Pass): Loans in this category are considered “pass” rated loans with low to average risk. Loans rated 4 (Monitor): These loans represent classified loans that management is closely monitoring for credit quality. These loans have had or may have minor credit quality deterioration as of March 31, 2016 and December 31, 2015. Loans rated 5 (Substandard): Substandard loans represent classified loans that management is closely monitoring for credit quality. These loans have had more significant credit quality deterioration as of March 31, 2016 and December 31, 2015. Loans rated 6 (Doubtful): Doubtful loans represent classified loans that management is closely monitoring for credit quality. These loans had more significant credit quality deterioration as of March 31, 2016 and December 31, 2015 and are doubtful for full collection. Impaired: Impaired loans represent classified loans that management is closely monitoring for credit quality. A loan is classified as impaired when it is probable that the Company will be unable to collect all amounts due. The following table presents the Company’s loans by risk rating at March 31, 2016. Construction Commercial Municipal Commercial Estate (in thousands) Grade: 1-3 (Pass) $ 19,492 $ 528,721 $ 85,227 $ 712,671 4 (Monitor) 6,982 18 — 912 5 (Substandard) — — — — 6 (Doubtful) — — — — Impaired 98 429 — 1,665 Total $ 26,572 $ 529,168 $ 85,227 $ 715,248 The following table presents the Company’s loans by risk rating at December 31, 2015. Construction Commercial Municipal Commercial (in thousands) Grade: 1-3 (Pass) $ 20,281 $ 451,774 $ 85,685 $ 718,911 4 (Monitor) 7,042 18 — 917 5 (Substandard) — — — — 6 (Doubtful) — — — — Impaired 98 443 — 1,678 Total $ 27,421 $ 452,235 $ 85,685 $ 721,506 The Company has increased its exposure to larger loans to large institutions with publically available credit ratings beginning in 2015. These ratings are tracked as a credit quality indicator for these loans. Credit ratings issued by national organizations were utilized as credit quality indicators as presented in the following table at March 31, 2016. Commercial Municipal Commercial Estate Total (in thousands) Credit Rating: Aaa – Aa3 $ 281,922 $ 63,407 $ 7,311 $ 352,640 A1 – A3 167,389 7,400 130,512 305,301 Baa1 – Baa3 — 8,890 166,796 175,686 Ba2 — 4,480 — 4,480 Total $ 449,311 $ 84,177 $ 304,619 838,107 The Company has increased its exposure to larger loans to large institutions with publically available credit ratings beginning in 2015. These ratings are tracked as a credit quality indicator for these loans. Credit ratings issued by national organizations were utilized as credit quality indicators as presented in the following table at December 31, 2015. Commercial Municipal Commercial Total (in thousands) Credit Rating: Aaa – Aa3 $ 234,733 $ 63,865 $ 7,547 $ 306,145 A1 – A3 140,419 7,400 130,872 278,691 Baa1 – Baa3 — 8,890 167,489 176,379 Ba2 — 4,480 — 4,480 Total $ 375,152 $ 84,635 $ 305,908 $ 765,695 The Company utilized payment performance as credit quality indicators for the loan types listed below. The indicators are depicted in the table “aging of past due loans,” below. Further information pertaining to the allowance for loan losses at March 31, 2016 follows: Accruing 30-89 Days Non Accrual Accruing 90 Days Total Current Total (in thousands) Construction and land development $ — $ 98 $ — $ 98 $ 26,474 $ 26,572 Commercial and industrial 226 56 — 282 528,886 529,168 Municipal — — — — 85,227 85,227 Commercial real estate 2,290 168 — 2,458 712,790 715,248 Residential real estate 1,037 1,036 — 2,073 212,967 215,040 Consumer and overdrafts 1 6 — 7 12,819 12,826 Home equity 539 126 — 665 177,712 178,377 Total $ 4,093 $ 1,490 $ — $ 5,583 $ 1,756,875 $ 1,762,458 Further information pertaining to the allowance for loan losses at December 31, 2015 follows: Accruing 30-89 Days Non Accrual Accruing Total Current Loans Total (in thousands) Construction and land development $ — $ 99 $ — $ 99 $ 27,322 $ 27,421 Commercial and industrial — 60 — 60 452,175 452,235 Municipal — — — — 85,685 85,685 Commercial real estate 1,462 174 — 1,636 719,870 721,506 Residential real estate 596 1,559 — 2,155 253,191 255,346 Consumer and overdrafts 6 — — 6 11,317 11,323 Home equity 628 444 — 1,072 176,948 178,020 Total $ 2,692 $ 2,336 $ — $ 5,028 $ 1,726,508 $ 1,731,536 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, 2015. The following is information pertaining to impaired loans for March 31, 2016: Carrying Value Unpaid Required Average Interest (in thousands) With no required reserve recorded: Construction and land development $ — $ — $ — $ — $ — Commercial and industrial 56 243 — 58 — Municipal — — — — — Commercial real estate — — — — — Residential real estate 109 195 — 111 2 Consumer — — — — — Home equity — — — — — Total $ 165 $ 438 $ — $ 169 $ 2 With required reserve recorded: Construction and land development $ 98 $ 108 $ 7 $ 98 $ — Commercial and industrial 373 388 17 378 5 Municipal — — — — — Commercial real estate 1,665 1,763 89 1,671 15 Residential real estate 796 797 27 799 — Consumer — — — — — Home equity 89 89 89 90 — Total $ 3,021 $ 3,145 $ 229 $ 3,036 $ 20 Total: Construction and land development $ 98 $ 108 $ 7 $ 98 $ — Commercial and industrial 429 631 17 436 5 Municipal — — — — — Commercial real estate 1,665 1,763 89 1,671 15 Residential real estate 905 992 27 910 2 Consumer — — — — — Home equity 89 89 89 90 — Total $ 3,186 $ 3,583 $ 229 $ 3,205 $ 22 The following is information pertaining to impaired loans for March 31, 2015: Carrying Value Unpaid Required Average Carrying Interest (in thousands) With no required reserve recorded: Construction and land development $ — $ — $ — $ — $ — Commercial and industrial 63 105 — 39 — Municipal — — — — — Commercial real estate 392 396 — 393 — Residential real estate 132 215 — 134 2 Consumer — — — — — Home equity — — — — — Total $ 587 $ 716 $ — $ 566 $ 2 With required reserve recorded: Construction and land development $ 102 $ 108 $ 20 $ 103 $ — Commercial and industrial 808 1,010 96 821 11 Municipal — — — — — Commercial real estate 3,912 4,006 631 3,918 16 Residential real estate 820 820 90 823 6 Consumer — — — — — Home equity 92 92 92 92 — Total $ 5,734 $ 6,036 $ 929 $ 5,757 $ 33 Total: Construction and land development $ 102 $ 108 $ 20 $ 103 $ — Commercial and industrial 871 1,115 96 860 11 Municipal — — — — — Commercial real estate 4,304 4,402 631 4,311 16 Residential real estate 952 1,035 90 957 8 Consumer — — — — — Home equity 92 92 92 92 — Total $ 6,321 $ 6,752 $ 929 $ 6,323 $ 35 There were no troubled debt restructurings occurring during the three month periods ended March 31, 2016 or March 31, 2015.

Reclassifications Out of Accumu

Reclassifications Out of Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2016
Text Block [Abstract]
Reclassifications Out of Accumulated Other Comprehensive Income	Note 5. Reclassifications Out of Accumulated Other Comprehensive Income (a) Amount Reclassified from Accumulated Other Comprehensive Income Details about Accumulated Other Three Months Ended March 31, 2016 Three Months Ended Affected Line Item (in thousands) Accretion of unrealized losses transferred $ (1,511 ) $ (1,129 ) Interest on securities held-to- Tax (expense) or benefit 527 394 Provision for income taxes Net of tax $ (984 ) $ (735 ) Net income Amortization of defined benefit pension items Prior-service costs $ (2 )(b) $ (3 )(b) Salaries and employee benefits Actuarial gains (losses) (401 )(b) (352 )(b) Salaries and employee benefits Total before tax (403 ) (355 ) Income before taxes Tax (expense) or benefit 161 142 Provision for income taxes Net of tax $ (242 ) $ (213 ) Net income Total reclassifications for the period $ (1,226 ) $ (948 ) Net income, net of tax (a) Amount in parentheses indicates reductions to net income. (b) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see employee benefits footnote (Note 7) for additional details).

Earnings per Share ("EPS")

Earnings per Share ("EPS")	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
Earnings per Share ("EPS")	Note 6. 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 Company had no common stock equivalents outstanding for the periods ended March 31, 2015 and 2016. The following table is a reconciliation of basic EPS and diluted EPS for the three months ended March 31, Three Months Ended March 31, (in thousands except share and per share data) 2016 2015 Basic EPS Computation: Numerator: Net income, Class A $ 4,168 $ 3,895 Net income, Class B 1,139 1,064 Denominator: Weighted average shares outstanding, Class A 3,600,729 3,600,729 Weighted average shares outstanding, Class B 1,967,180 1,967,180 Basic EPS, Class A $ 1.16 $ 1.08 Basic EPS, Class B 0.58 0.54 Diluted EPS Computation: Numerator: Net income, Class A $ 4,168 $ 3,895 Net income, Class B 1,139 1,064 Total net income, for diluted EPS, Class A computation 5,307 4,959 Denominator: Weighted average shares outstanding, basic, Class A 3,600,729 3,600,729 Weighted average shares outstanding, Class B 1,967,180 1,967,180 Weighted average shares outstanding diluted, 5,567,909 5,567,909 Weighted average shares outstanding, Class B 1,967,180 1,967,180 Diluted EPS, Class A $ 0.95 $ 0.89 Diluted EPS, Class B 0.58 0.54

Employee Benefits

Employee Benefits	3 Months Ended
	Mar. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Employee Benefits	Note 7. 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. Effective January 1, 2016, the Company changed its estimate of the service and interest components of the net periodic benefit cost. Previously, the Company estimated the service and interest cost components utilizing a single weighted-average discount rate derived from the yield curve used to measure the benefit obligation. The new estimate utilizes a full yield curve approach in the estimation of these components by applying the specific spot rates along the yield curve used in the determination of the benefit obligation to their underlying projected cash flows. The new estimate provided a more precise measurement of service and interests costs by improving the correlation between projected benefit cash flows and their corresponding spot rates. The change does not affect the measurement of the Company’s benefit obligations and it is accounted for as a change in accounting estimate, which is applied prospectively. Components of Net Periodic Benefit Cost (Credit) for the Three Months Ended March 31, Pension Benefits Supplemental Insurance/ Retirement Plan 2016 2015 2016 2015 (in thousands) Service cost $ 318 $ 336 $ 455 $ 397 Interest 340 394 334 341 Expected return on plan assets (694 ) (688 ) — — Recognized prior service cost (benefit) (26 ) (26 ) 29 29 Recognized net actuarial losses 200 203 200 150 Net periodic benefit (credit) cost $ 138 $ 219 $ 1,018 $ 917 Contributions The company intends to contribute $2,075,000 to the Pension Plan in 2016. As of March 31, 2016, $1,325,000 has been contributed.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 8. Fair Value Measurements The Company follows FASB ASC 820-10, Fair Value Measurements and Disclosures 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 and municipal bonds. 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, and distressed debt and non-investment grade residual interests in securitizations. The results of the fair value hierarchy as of March 31, 2016, are as follows: Financial Instruments Measured at Fair Value on a Recurring Basis: Securities AFS Fair Value Measurements Using Carrying Quoted Prices (Level 1) Significant Significant (Level 3) (in thousands) U.S. Treasury $ 1,997 $ — $ 1,997 $ — U.S. Government Sponsored Enterprises 5,008 — 5,008 — SBA Backed Securities 5,931 — 5,931 — U.S. Government Agency and Sponsored Mortgage Backed Securities 226,293 — 226,293 — Privately Issued Residential Mortgage Backed Securities 1,345 — 1,345 — Obligations Issued by States and Political Subdivisions 135,089 — — 135,089 Other Debt Securities 4,469 — 4,469 — Equity Securities 217 217 — — Total $ 380,349 $ 217 $ 245,043 $ 135,089 Financial Instruments Measured at Fair Value on a Non-recurring Basis: Impaired Loans 1,044 — — 1,044 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, appraisal of collateral or other type of real estate tax assessment. The types of adjustments that are made to specific provisions (credits) relate to impaired loans recognized for the three month period ended March 31, 2016 amounted to ($14,000). There were no transfers between level 1, 2 and 3 for the three months ended March 31, 2016. There were no liabilities measured at fair value on a recurring or nonrecurring basis during the three month period ended March 31, 2016. The following table presents additional information about assets measured at fair value on a recurring and nonrecurring basis for which the Company has utilized Level 3 inputs to determine fair value (dollars in thousands). Management continues to monitor the assumptions used to value the assets listed below. Asset Fair Value Valuation Technique Unobservable Input Unobservable Input Securities AFS (4) $ 135,089 Discounted cash flow Discount rate 0%-1% (3) Impaired Loans 1,044 Appraisal of collateral (1) Appraisal adjustments (2) 0%-30% discount (1) Fair value is generally determined through independent appraisals of the underlying collateral, which generally include various Level 3 inputs which are not identifiable. (2) Appraisals may be adjusted by management for qualitative factors such as economic conditions and estimated expenses. (3) Weighted averages. (4) Municipal securities generally have maturities of one year or less and, therefore, the amortized cost equates to the fair value. The changes in Level 3 securities for the three-month period ended March 31, 2016 are shown in the table below: Auction Rate Securities Obligations Issued by States & Political Subdivisions Equity Securities Total (in thousands) Balance at December 31, 2015 $ 3,820 $ 153,140 $ 37 $ 156,997 Purchases — 15,935 — 15,935 Maturities and calls — (38,251 ) (37 ) (38,288 ) Amortization — (33 ) — (33 ) Changes in fair value 478 — — 478 Balance at March 31, 2016 $ 4,298 $ 130,791 $ — $ 135,089 The amortized cost of Level 3 securities was $135,490,000 at March 31, 2016 with an unrealized loss of $401,000. The securities in this category are generally equity investments, municipal securities with no readily determinable fair value or failed auction rate securities. Management evaluated the fair value of these securities based on an evaluation of the underlying issuer, prevailing rates and market liquidity. The changes in Level 3 securities for the three-month period ended March 31, 2015, are shown in the table below: Auction Rate Obligations Equity Total (in thousands) Balance at December 31, 2014 $ 3,820 $ 92,964 $ 102 $ 96.886 Purchases — 41,909 — 41,909 Maturities and calls — (19,914 ) — (19,914 ) Amortization — (6 ) — (6 ) Changes in fair value — — — — Balance at March 31, 2015 $ 3,820 $ 114,953 $ 102 $ 118,875 The amortized cost of Level 3 securities was $119,750,000 at March 31, 2015 with an unrealized loss of $875,000. 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 results of the fair value hierarchy as of December 31, 2015, are as follows: Financial Instruments Measured at Fair Value on a Recurring Basis: Securities AFS Fair Value Measurements Using Carrying Quoted Prices Significant Significant (in thousands) U.S. Treasury $ 1,989 $ — $ 1,989 $ — U.S. Government Sponsored Enterprises — — — — SBA Backed Securities 5,989 — 5,989 — U.S. Government Agency and Sponsored Mortgage Backed Securities 233,526 — 233,526 — Privately Issued Residential Mortgage Backed Securities 1,434 — 1,434 — Obligations Issued by States and Political Subdivisions 156,960 — — 156,960 Other Debt Securities 4,473 — 4,473 — Equity Securities 252 215 — 37 Total $ 404,623 $ 215 $ 247,411 $ 156,997 Financial Instruments Measured at Fair Value on a Non-recurring Basis: Impaired Loans $ 1,056 $ — $ — $ 1,056 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, appraisal of collateral 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 period ended 2015 for the estimated credit loss amounted to $165,000. There were no transfers between level 1, 2 and 3 for the year ended December 31, 2015. There were no liabilities measured at fair value on a recurring or nonrecurring basis during the year ended December 31, 2015. The following table presents additional information about assets measured at fair value on a recurring and nonrecurring basis for which the Company has utilized Level 3 inputs to determine fair value (dollars in thousands). Management continues to monitor the assumptions used to value the assets listed below. Asset Fair Value Valuation Technique Unobservable Input Unobservable Input Securities AFS (4) $ 156,997 Discounted cash flow Discount rate 0%-1% (3) Impaired Loans 1,056 Appraisal of collateral (1) Appraisal adjustments (2) 0%-30% 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.

Fair Values of Financial Instru

Fair Values of Financial Instruments	3 Months Ended
	Mar. 31, 2016
Investments, All Other Investments [Abstract]
Fair Values of Financial Instruments	Note 9. 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 Held-for-Sale: Fair value is measured using quoted market prices when available. These assets are typically categorized as Level 1. If quoted market prices are not available, comparable market values may be utilized. These assets are typically categorized as Level 2. Loans: For variable-rate loans, that reprice frequently and with no significant change in credit risk, fair values are based on carrying amounts. The fair value of other loans is estimated using discounted cash flow analysis, based on interest rates currently being offered for loans with similar terms to borrowers of similar credit quality. Incremental credit risk for nonperforming loans has been considered. Time deposits: The fair value of time deposits was estimated using a discounted cash flow approach that applies prevailing market interest rates for similar maturity instruments. The fair values of the Company’s time deposit liabilities do not take into consideration the value of the Company’s long-term relationships with depositors, which may have significant value. Other borrowed funds: The fair value of other borrowed funds is based on the discounted value of contractual cash flows. The discount rate used is estimated based on the rates currently offered for other borrowed funds of similar remaining maturities. Subordinated debentures: The fair value of subordinated debentures is based on the discounted value of contractual cash flows. The discount rate used is estimated based on the rates currently offered for other subordinated debentures of similar remaining maturities. The following presents (in thousands) the carrying amount, estimated fair value, and placement in the fair value hierarchy of the Company’s financial instruments as of March 31, 2016 and December 31, 2015. 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. Carrying Amount Estimated Fair Value Fair Value Measurements Level 1 Inputs Level 2 Inputs Level 3 Inputs March 31, 2016 (in thousands) Financial assets: Securities held-to-maturity $ 1,412,702 $ 1,437,205 $ — $ 1,437,205 $ — Loans Held-for-Sale 48,180 48,958 48,958 Loans (1) 1,738,914 1,750,498 — — 1,750,498 Financial liabilities: Time deposits 446,185 448,690 — 448,690 — Other borrowed funds 356,000 365,342 — 365,342 — Subordinated debentures 36,083 36,083 — — 36,083 December 31, 2015 Financial assets: Securities held-to-maturity 1,438,903 1,438,960 — 1,438,960 — Loans (1) 1,708,461 1,677,270 — — 1,677,270 Financial liabilities: Time deposits 473,426 474,046 — 474,046 — Other borrowed funds 368,000 372,209 — 372,209 — Subordinated debentures 36,083 36,083 — — 36,083 (1) Comprised of loans (including collateral dependent impaired loans), net of deferred loan costs and the allowance for loan losses.

Recent Accounting Developments

Recent Accounting Developments	3 Months Ended
	Mar. 31, 2016
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Developments	Note 10. Recent Accounting Developments In January 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-1, Recognition and Measurement of Financial Assets and Financial Liabilities In February 2016, the FASB issued ASU 2016-02, Leases. In March 2016, the FASB issued ASU 2016-07, Investments—Equity Method and Joint Ventures Simplifying the Transition to the Equity Method of Accounting

Securities Available-for-Sale (

Securities Available-for-Sale (Tables)	3 Months Ended
	Mar. 31, 2016
Text Block [Abstract]
Summary of Securities Available-for-Sale	March 31, 2016 December 31, 2015 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value (in thousands) U.S. Treasury $ 1,999 $ — $ 2 $ 1,997 $ 1,999 $ — $ 10 $ 1,989 U.S. Government Sponsored Enterprises 5,000 8 — 5,008 — — — — SBA Backed Securities 5,925 10 4 5,931 5,983 8 2 5,989 U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities 225,727 759 193 226,293 232,967 859 300 233,526 Privately Issued Residential Mortgage Backed Securities 1,362 2 19 1,345 1,437 10 13 1,434 Obligations Issued by States and Political Subdivisions 135,490 — 401 135,089 157,838 — 878 156,960 Other Debt Securities 4,600 — 131 4,469 4,600 3 130 4,473 Equity Securities 116 101 — 217 153 99 — 252 Total $ 380,219 $ 880 $ 750 $ 380,349 $ 404,977 $ 979 $ 1,333 $ 404,623
Maturity Distribution of Securities Available-for-Sale	The following table shows the maturity distribution of the Company’s securities available-for-sale at March 31, 2016. Amortized Cost Fair Value (in thousands) Within one year $ 129,038 $ 129,037 After one but within five years 160,638 161,034 After five but within ten years 83,228 83,391 More than 10 years 5,699 5,283 Non-maturing 1,616 1,604 Total $ 380,219 $ 380,349
Continuous Unrealized Loss Position for 12 Months or Less and 12 Months or Longer	The following table shows the temporarily impaired securities of the Company’s available-for-sale portfolio at March 31, 2016. 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 10 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 267 holdings at March 31, 2016. March 31, 2016 Less than 12 months 12 months or longer Total Temporarily Impaired Investments Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized (in thousands) U.S. Treasury $ — $ — $ 1,997 $ 2 $ 1,997 $ 2 Small Business Administration 1,799 4 — — 1,799 4 U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities 46,435 113 29,009 80 75,444 193 Privately Issued Residential Mortgage Backed Securities 429 2 471 17 900 19 Obligations Issued by States and Political Subdivisions — — 4,298 401 4,298 401 Other Debt Securities 1,184 17 1,685 114 2,869 131 Total temporarily impaired securities $ 49,847 $ 136 $ 37,460 $ 614 $ 87,307 $ 750 The following table shows the temporarily impaired securities of the Company’s available-for-sale portfolio at December 31, 2015. 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 14 and 11 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 290 holdings at December 31, 2015. December 31, 2015 Less than 12 months 12 months or longer Total Temporarily Impaired Investments Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized (in thousands) U.S. Treasury $ 1,989 $ 10 $ — $ — $ 1,989 $ 10 SBA Backed Securities 1,031 2 — — 1,031 2 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 26,519 52 49,341 248 75,860 300 Privately Issued Residential Mortgage-Backed Securities — — 490 13 490 13 Obligations Issued by States and Political Subdivisions — — 3,820 878 3,820 878 Other Debt Securities 497 3 1,373 127 1,870 130 $ 30,036 $ 67 $ 55,024 $ 1,266 $ 85,060 $ 1,333

Investment Securities Held-to20

Investment Securities Held-to-Maturity (Tables)	3 Months Ended
	Mar. 31, 2016
Text Block [Abstract]
Summary of Held-to-Maturity Securities	March 31, 2016 December 31, 2015 Amortized Gross Gross Estimated Value Amortized Gross Gross Estimated (in thousands) U.S. Government Sponsored Enterprises $ 152,732 $ 3,033 $ 11 $ 155,754 $ 186,734 $ 2,234 $ 141 $ 188,827 U.S. Government Agency and Sponsored Enterprises Mortgage Backed Securities 1,259,970 22,843 1,362 1,281,451 1,252,169 7,547 9,583 1,250,133 Total $ 1,412,702 $ 25,876 $ 1,373 $ 1,437,205 $ 1,438,903 $ 9,781 $ 9,724 $ 1,438,960
Company's Securities Held-to-Maturity	The following table shows the maturity distribution of the Company’s securities held-to-maturity at March 31, 2016. Amortized Fair Value (in thousands) Within one year $ 9,242 $ 9,343 After one but within five years 1,205,411 1,223,805 After five but within ten years 193,283 199,272 More than ten years 4,766 4,785 Total $ 1,412,702 $ 1,437,205
Unrealized Market Loss of Securities	The following table shows the temporarily impaired securities of the Company’s held-to-maturity portfolio at March 31, 2016. 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 24 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 326 holdings at March 31, 2016. March 31, 2016 Less Than 12 Months 12 Months or Longer Total Temporarily Impaired Investments Fair Value Unrealized Fair Value Unrealized Fair Value Unrealized (in thousands) U.S. Government Sponsored Enterprises $ 19,990 $ 11 $ — $ — $ 19,990 $ 11 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 91,770 379 120,167 983 211,937 1,362 Total temporarily impaired securities $ 111,760 $ 390 $ 120,167 $ 983 $ 231,927 $ 1,373 The following table shows the temporarily impaired securities of the Company’s held-to-maturity portfolio at December 31, 2015. 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 101 and 26 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 322 holdings at December 31, 2015. December 31, 2015 Less Than 12 Months 12 Months or Longer Total Temporarily Impaired Investments Fair Value Unrealized Fair Unrealized Fair Value Unrealized (in thousands) U.S. Government Sponsored Enterprises $ 9,859 $ 141 $ — $ — $ 9,859 $ 141 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 626,218 6,657 123,864 2,926 750,082 9,583 Total temporarily impaired securities $ 636,077 $ 6,798 $ 123,864 $ 2,926 $ 759,941 $ 9,724

Allowance for Loan Losses (Tabl

Allowance for Loan Losses (Tables)	3 Months Ended
	Mar. 31, 2016
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 2016 2015 (in thousands) Allowance for loan losses, beginning of period $ 23,075 $ 22,318 Loans charged off (69 ) (81 ) Recoveries on loans previously charged-off 88 92 Net recoveries (charge-offs) 19 11 Provision charged to expense 450 200 Allowance for loan losses, end of period $ 23,544 $ 22,529
Summary of Allowance for Loan Losses	Further information pertaining to the allowance for loan losses for the three months ending March 31, 2016 follows: Construction Commercial Municipal Commercial Estate Residential Consumer Home Unallocated Total (in thousands) Allowance for loan losses: Balance at $ 2,041 $ 5,899 $ 994 $ 10,589 $ 1,320 $ 644 $ 1,077 $ 511 $ 23,075 Charge-offs — — — — — (69 ) — — (69 ) Recoveries — 35 — — 2 51 — — 88 Provision (68 ) 759 (4 ) (56 ) (73 ) 67 108 (283 ) 450 Ending balance at March 31, 2016 $ 1,973 $ 6,693 $ 990 $ 10,533 $ 1,249 $ 693 $ 1,185 $ 228 $ 23,544 Amount of allowance for loan losses for loans deemed to be $ 7 $ 17 $ — $ 89 $ 27 $ — $ 89 $ — 229 Amount of allowance for loan losses for loans not deemed to be impaired $ 1,966 $ 6,676 $ 990 $ 10,444 $ 1,222 $ 693 $ 1,096 $ 228 $ 23,315 Loans: Ending balance $ 26,572 $ 529,168 $ 85,227 $ 715,248 $ 215,040 $ 12,826 $ 178,377 $ — $ 1,762,458 Loans deemed to be impaired $ 98 $ 429 $ — $ 1,665 $ 905 $ — $ 89 $ — $ 3,186 Loans not deemed to be impaired $ 26,474 $ 528,739 $ 85,227 $ 713,583 $ 214,135 $ 12,826 $ 178,288 $ — $ 1,759,272 Further information pertaining to the allowance for loan losses for the three months ending March 31, 2015 follows: Construction Commercial Municipal Commercial Residential Consumer Home Unallocated Total (in thousands) Allowance for loan losses: Balance at December 31, 2014 $ 1,592 $ 4,758 $ 1,488 $ 11,199 $ 775 $ 810 $ 599 $ 1,097 $ 22,318 Charge-offs — — — — — (81 ) — — (81 ) Recoveries — 15 — 2 2 73 — — 92 Provision 292 (128 ) (115 ) (74 ) 22 (88 ) 15 276 200 Ending balance at March 31, 2015 $ 1,884 $ 4,645 $ 1,373 $ 11,127 $ 799 $ 714 $ 614 $ 1,373 $ 22,529 Amount of allowance for loan losses for loans deemed to be impaired $ 20 $ 96 $ — $ 631 $ 90 $ — $ 92 $ — 929 Amount of allowance for loan losses for loans not deemed to be impaired $ 1,864 $ 4,549 $ 1,373 $ 10,496 $ 709 $ 714 $ 522 $ 1,373 $ 21,600 Loans: Ending balance $ 25,347 $ 157,637 $ 41,406 $ 691,811 $ 258,558 $ 10,508 $ 156,063 $ — $ 1,341,330 Loans deemed to be impaired $ 102 $ 871 $ — $ 4,304 $ 952 $ — $ 92 $ — $ 6,321 Loans not deemed to be impaired $ 25,245 $ 156,766 $ 41,406 $ 687,507 $ 257,606 $ 10,508 $ 155,971 $ — $ 1,335,009
Loans by Risk Rating	The following table presents the Company’s loans by risk rating at March 31, 2016. Construction Commercial Municipal Commercial Estate (in thousands) Grade: 1-3 (Pass) $ 19,492 $ 528,721 $ 85,227 $ 712,671 4 (Monitor) 6,982 18 — 912 5 (Substandard) — — — — 6 (Doubtful) — — — — Impaired 98 429 — 1,665 Total $ 26,572 $ 529,168 $ 85,227 $ 715,248 The following table presents the Company’s loans by risk rating at December 31, 2015. Construction Commercial Municipal Commercial (in thousands) Grade: 1-3 (Pass) $ 20,281 $ 451,774 $ 85,685 $ 718,911 4 (Monitor) 7,042 18 — 917 5 (Substandard) — — — — 6 (Doubtful) — — — — Impaired 98 443 — 1,678 Total $ 27,421 $ 452,235 $ 85,685 $ 721,506
Loans by Credit Ratings Issued by National Organizations	Credit ratings issued by national organizations were utilized as credit quality indicators as presented in the following table at March 31, 2016. Commercial Municipal Commercial Estate Total (in thousands) Credit Rating: Aaa – Aa3 $ 281,922 $ 63,407 $ 7,311 $ 352,640 A1 – A3 167,389 7,400 130,512 305,301 Baa1 – Baa3 — 8,890 166,796 175,686 Ba2 — 4,480 — 4,480 Total $ 449,311 $ 84,177 $ 304,619 838,107 Credit ratings issued by national organizations were utilized as credit quality indicators as presented in the following table at December 31, 2015. Commercial Municipal Commercial Total (in thousands) Credit Rating: Aaa – Aa3 $ 234,733 $ 63,865 $ 7,547 $ 306,145 A1 – A3 140,419 7,400 130,872 278,691 Baa1 – Baa3 — 8,890 167,489 176,379 Ba2 — 4,480 — 4,480 Total $ 375,152 $ 84,635 $ 305,908 $ 765,695
Aging of Past Due Loan Losses	Further information pertaining to the allowance for loan losses at March 31, 2016 follows: Accruing 30-89 Days Non Accrual Accruing 90 Days Total Current Total (in thousands) Construction and land development $ — $ 98 $ — $ 98 $ 26,474 $ 26,572 Commercial and industrial 226 56 — 282 528,886 529,168 Municipal — — — — 85,227 85,227 Commercial real estate 2,290 168 — 2,458 712,790 715,248 Residential real estate 1,037 1,036 — 2,073 212,967 215,040 Consumer and overdrafts 1 6 — 7 12,819 12,826 Home equity 539 126 — 665 177,712 178,377 Total $ 4,093 $ 1,490 $ — $ 5,583 $ 1,756,875 $ 1,762,458 Further information pertaining to the allowance for loan losses at December 31, 2015 follows: Accruing 30-89 Days Non Accrual Accruing Total Current Loans Total (in thousands) Construction and land development $ — $ 99 $ — $ 99 $ 27,322 $ 27,421 Commercial and industrial — 60 — 60 452,175 452,235 Municipal — — — — 85,685 85,685 Commercial real estate 1,462 174 — 1,636 719,870 721,506 Residential real estate 596 1,559 — 2,155 253,191 255,346 Consumer and overdrafts 6 — — 6 11,317 11,323 Home equity 628 444 — 1,072 176,948 178,020 Total $ 2,692 $ 2,336 $ — $ 5,028 $ 1,726,508 $ 1,731,536
Information Pertaining to Impaired Loans	The following is information pertaining to impaired loans for March 31, 2016: Carrying Value Unpaid Required Average Interest (in thousands) With no required reserve recorded: Construction and land development $ — $ — $ — $ — $ — Commercial and industrial 56 243 — 58 — Municipal — — — — — Commercial real estate — — — — — Residential real estate 109 195 — 111 2 Consumer — — — — — Home equity — — — — — Total $ 165 $ 438 $ — $ 169 $ 2 With required reserve recorded: Construction and land development $ 98 $ 108 $ 7 $ 98 $ — Commercial and industrial 373 388 17 378 5 Municipal — — — — — Commercial real estate 1,665 1,763 89 1,671 15 Residential real estate 796 797 27 799 — Consumer — — — — — Home equity 89 89 89 90 — Total $ 3,021 $ 3,145 $ 229 $ 3,036 $ 20 Total: Construction and land development $ 98 $ 108 $ 7 $ 98 $ — Commercial and industrial 429 631 17 436 5 Municipal — — — — — Commercial real estate 1,665 1,763 89 1,671 15 Residential real estate 905 992 27 910 2 Consumer — — — — — Home equity 89 89 89 90 — Total $ 3,186 $ 3,583 $ 229 $ 3,205 $ 22 The following is information pertaining to impaired loans for March 31, 2015: Carrying Value Unpaid Required Average Carrying Interest (in thousands) With no required reserve recorded: Construction and land development $ — $ — $ — $ — $ — Commercial and industrial 63 105 — 39 — Municipal — — — — — Commercial real estate 392 396 — 393 — Residential real estate 132 215 — 134 2 Consumer — — — — — Home equity — — — — — Total $ 587 $ 716 $ — $ 566 $ 2 With required reserve recorded: Construction and land development $ 102 $ 108 $ 20 $ 103 $ — Commercial and industrial 808 1,010 96 821 11 Municipal — — — — — Commercial real estate 3,912 4,006 631 3,918 16 Residential real estate 820 820 90 823 6 Consumer — — — — — Home equity 92 92 92 92 — Total $ 5,734 $ 6,036 $ 929 $ 5,757 $ 33 Total: Construction and land development $ 102 $ 108 $ 20 $ 103 $ — Commercial and industrial 871 1,115 96 860 11 Municipal — — — — — Commercial real estate 4,304 4,402 631 4,311 16 Residential real estate 952 1,035 90 957 8 Consumer — — — — — Home equity 92 92 92 92 — Total $ 6,321 $ 6,752 $ 929 $ 6,323 $ 35

Reclassifications Out of Accu22

Reclassifications Out of Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2016
Text Block [Abstract]
Reclassifications Out of Accumulated Other Comprehensive Income	Amount Reclassified from Accumulated Other Comprehensive Income Details about Accumulated Other Three Months Ended March 31, 2016 Three Months Ended Affected Line Item (in thousands) Accretion of unrealized losses transferred $ (1,511 ) $ (1,129 ) Interest on securities held-to- Tax (expense) or benefit 527 394 Provision for income taxes Net of tax $ (984 ) $ (735 ) Net income Amortization of defined benefit pension items Prior-service costs $ (2 )(b) $ (3 )(b) Salaries and employee benefits Actuarial gains (losses) (401 )(b) (352 )(b) Salaries and employee benefits Total before tax (403 ) (355 ) Income before taxes Tax (expense) or benefit 161 142 Provision for income taxes Net of tax $ (242 ) $ (213 ) Net income Total reclassifications for the period $ (1,226 ) $ (948 ) Net income, net of tax (a) Amount in parentheses indicates reductions to net income. (b) These accumulated other comprehensive income components are included in the computation of net periodic pension cost (see employee benefits footnote (Note 7) for additional details).

Earnings per Share ("EPS") (Tab

Earnings per Share ("EPS") (Tables)	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
Reconciliation of Basic EPS and Diluted EPS	The following table is a reconciliation of basic EPS and diluted EPS for the three months ended March 31, Three Months Ended March 31, (in thousands except share and per share data) 2016 2015 Basic EPS Computation: Numerator: Net income, Class A $ 4,168 $ 3,895 Net income, Class B 1,139 1,064 Denominator: Weighted average shares outstanding, Class A 3,600,729 3,600,729 Weighted average shares outstanding, Class B 1,967,180 1,967,180 Basic EPS, Class A $ 1.16 $ 1.08 Basic EPS, Class B 0.58 0.54 Diluted EPS Computation: Numerator: Net income, Class A $ 4,168 $ 3,895 Net income, Class B 1,139 1,064 Total net income, for diluted EPS, Class A computation 5,307 4,959 Denominator: Weighted average shares outstanding, basic, Class A 3,600,729 3,600,729 Weighted average shares outstanding, Class B 1,967,180 1,967,180 Weighted average shares outstanding diluted, 5,567,909 5,567,909 Weighted average shares outstanding, Class B 1,967,180 1,967,180 Diluted EPS, Class A $ 0.95 $ 0.89 Diluted EPS, Class B 0.58 0.54

Employee Benefits (Tables)

Employee Benefits (Tables)	3 Months Ended
	Mar. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Components of Net Periodic Benefit Cost (Credit)	Components of Net Periodic Benefit Cost (Credit) for the Three Months Ended March 31, Pension Benefits Supplemental Insurance/ Retirement Plan 2016 2015 2016 2015 (in thousands) Service cost $ 318 $ 336 $ 455 $ 397 Interest 340 394 334 341 Expected return on plan assets (694 ) (688 ) — — Recognized prior service cost (benefit) (26 ) (26 ) 29 29 Recognized net actuarial losses 200 203 200 150 Net periodic benefit (credit) cost $ 138 $ 219 $ 1,018 $ 917

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2016
Fair Value Disclosures [Abstract]
Financial Instruments Measured at Fair Value on a Recurring and Non-recurring Basis	The results of the fair value hierarchy as of March 31, 2016, are as follows: Financial Instruments Measured at Fair Value on a Recurring Basis: Securities AFS Fair Value Measurements Using Carrying Quoted Prices (Level 1) Significant Significant (Level 3) (in thousands) U.S. Treasury $ 1,997 $ — $ 1,997 $ — U.S. Government Sponsored Enterprises 5,008 — 5,008 — SBA Backed Securities 5,931 — 5,931 — U.S. Government Agency and Sponsored Mortgage Backed Securities 226,293 — 226,293 — Privately Issued Residential Mortgage Backed Securities 1,345 — 1,345 — Obligations Issued by States and Political Subdivisions 135,089 — — 135,089 Other Debt Securities 4,469 — 4,469 — Equity Securities 217 217 — — Total $ 380,349 $ 217 $ 245,043 $ 135,089 Financial Instruments Measured at Fair Value on a Non-recurring Basis: Impaired Loans 1,044 — — 1,044 The results of the fair value hierarchy as of December 31, 2015, are as follows: Financial Instruments Measured at Fair Value on a Recurring Basis: Securities AFS Fair Value Measurements Using Carrying Quoted Prices Significant Significant (in thousands) U.S. Treasury $ 1,989 $ — $ 1,989 $ — U.S. Government Sponsored Enterprises — — — — SBA Backed Securities 5,989 — 5,989 — U.S. Government Agency and Sponsored Mortgage Backed Securities 233,526 — 233,526 — Privately Issued Residential Mortgage Backed Securities 1,434 — 1,434 — Obligations Issued by States and Political Subdivisions 156,960 — — 156,960 Other Debt Securities 4,473 — 4,473 — Equity Securities 252 215 — 37 Total $ 404,623 $ 215 $ 247,411 $ 156,997 Financial Instruments Measured at Fair Value on a Non-recurring Basis: Impaired Loans $ 1,056 $ — $ — $ 1,056
Assets Measured at Fair Value	The following table presents additional information about assets measured at fair value on a recurring and nonrecurring basis for which the Company has utilized Level 3 inputs to determine fair value (dollars in thousands). Management continues to monitor the assumptions used to value the assets listed below. Asset Fair Value Valuation Technique Unobservable Input Unobservable Input Securities AFS (4) $ 135,089 Discounted cash flow Discount rate 0%-1% (3) Impaired Loans 1,044 Appraisal of collateral (1) Appraisal adjustments (2) 0%-30% 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 following table presents additional information about assets measured at fair value on a recurring and nonrecurring basis for which the Company has utilized Level 3 inputs to determine fair value (dollars in thousands). Management continues to monitor the assumptions used to value the assets listed below. Asset Fair Value Valuation Technique Unobservable Input Unobservable Input Securities AFS (4) $ 156,997 Discounted cash flow Discount rate 0%-1% (3) Impaired Loans 1,056 Appraisal of collateral (1) Appraisal adjustments (2) 0%-30% discount (1) Fair value is generally determined through independent appraisals of the underlying collateral, which generally include various Level 3 inputs which are not identifiable. (2) Appraisals may be adjusted by management for qualitative factors such as economic conditions and estimated expenses. (3) Weighted averages (4) Municipal securities generally have maturities of one year or less and, therefore, the amortized cost equates to the fair value.
Changes in Level 3 Securities	The changes in Level 3 securities for the three-month period ended March 31, 2016 are shown in the table below: Auction Rate Securities Obligations Issued by States & Political Subdivisions Equity Securities Total (in thousands) Balance at December 31, 2015 $ 3,820 $ 153,140 $ 37 $ 156,997 Purchases — 15,935 — 15,935 Maturities and calls — (38,251 ) (37 ) (38,288 ) Amortization — (33 ) — (33 ) Changes in fair value 478 — — 478 Balance at March 31, 2016 $ 4,298 $ 130,791 $ — $ 135,089 The changes in Level 3 securities for the three-month period ended March 31, 2015, are shown in the table below: Auction Rate Obligations Equity Total (in thousands) Balance at December 31, 2014 $ 3,820 $ 92,964 $ 102 $ 96.886 Purchases — 41,909 — 41,909 Maturities and calls — (19,914 ) — (19,914 ) Amortization — (6 ) — (6 ) Changes in fair value — — — — Balance at March 31, 2015 $ 3,820 $ 114,953 $ 102 $ 118,875

Fair Values of Financial Inst26

Fair Values of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2016
Investments, All Other Investments [Abstract]
Carrying Amounts and Fair Values of Company's Financial Instruments	The following presents (in thousands) the carrying amount, estimated fair value, and placement in the fair value hierarchy of the Company’s financial instruments as of March 31, 2016 and December 31, 2015. 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. Carrying Amount Estimated Fair Value Fair Value Measurements Level 1 Inputs Level 2 Inputs Level 3 Inputs March 31, 2016 (in thousands) Financial assets: Securities held-to-maturity $ 1,412,702 $ 1,437,205 $ — $ 1,437,205 $ — Loans Held-for-Sale 48,180 48,958 48,958 Loans (1) 1,738,914 1,750,498 — — 1,750,498 Financial liabilities: Time deposits 446,185 448,690 — 448,690 — Other borrowed funds 356,000 365,342 — 365,342 — Subordinated debentures 36,083 36,083 — — 36,083 December 31, 2015 Financial assets: Securities held-to-maturity 1,438,903 1,438,960 — 1,438,960 — Loans (1) 1,708,461 1,677,270 — — 1,677,270 Financial liabilities: Time deposits 473,426 474,046 — 474,046 — Other borrowed funds 368,000 372,209 — 372,209 — Subordinated debentures 36,083 36,083 — — 36,083 (1) Comprised of loans (including collateral dependent impaired loans), net of deferred loan costs and the allowance for loan losses.

Basis of Financial Statement 27

Basis of Financial Statement Presentation - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2016Segment
Basis Of Presentation [Line Items]
Number of reportable segments	1
Century Bancorp Capital Trust II [Member]
Basis Of Presentation [Line Items]
Equity ownership interest	100.00%

Securities Available-for-Sale -

Securities Available-for-Sale - Summary of Securities Available-for-Sale (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 380,219	$ 404,977
Gross Unrealized Gains	880	979
Gross Unrealized Losses	750	1,333
Total, Fair Value	380,349	404,623
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,999	1,999
Gross Unrealized Losses	2	10
Total, Fair Value	1,997	1,989
U.S. Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,000
Gross Unrealized Gains	8
Total, Fair Value	5,008
Small Business Administration [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,925	5,983
Gross Unrealized Gains	10	8
Gross Unrealized Losses	4	2
Total, Fair Value	5,931	5,989
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	225,727	232,967
Gross Unrealized Gains	759	859
Gross Unrealized Losses	193	300
Total, Fair Value	226,293	233,526
Privately Issued Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,362	1,437
Gross Unrealized Gains	2	10
Gross Unrealized Losses	19	13
Total, Fair Value	1,345	1,434
Obligations Issued by States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	135,490	157,838
Gross Unrealized Losses	401	878
Total, Fair Value	135,089	156,960
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,600	4,600
Gross Unrealized Gains		3
Gross Unrealized Losses	131	130
Total, Fair Value	4,469	4,473
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	116	153
Gross Unrealized Gains	101	99
Total, Fair Value	$ 217	$ 252

Securities Available-for-Sale29

Securities Available-for-Sale - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2016USD ($)Security	Mar. 31, 2015USD ($)	Dec. 31, 2015USD ($)Security
Schedule of Available-for-sale Securities [Line Items]
Securities at fair value pledged to secure public deposits and repurchase agreements	$ 1,001,953,000		$ 1,004,743,000
Securities available-for-sale are securities pledged for borrowing	$ 19,103,000		$ 20,056,000
Securities AFS [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted average remaining life of investment securities available-for-sale	3 years 3 months 18 days
Number of securities, temporarily impaired for less than 12 months | Security	20		14
Number of securities, temporarily impaired for 12 months or longer | Security	10		11
Number of securities, temporarily impaired, total | Security	267		290
Federal Home Loan Bank Boston [Member]
Schedule of Available-for-sale Securities [Line Items]
Net gains on sales of securities	$ 0	$ 0
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities at fair value pledged to secure public deposits and repurchase agreements	213,639,000		$ 220,482,000
U.S. Government Sponsored Enterprises [Member] | Securities AFS [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted average remaining life	$ 5,000,000

Securities Available-for-Sale30

Securities Available-for-Sale - Maturity Distribution of Securities Available-for-Sale (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Within one year, Amortized Cost	$ 129,038
After one but within five years, Amortized Cost	160,638
After five but within ten years, Amortized Cost	83,228
More than ten years, Amortized Cost	5,699
Non-maturing, Amortized Cost	1,616
Amortized Cost	380,219	$ 404,977
Within one year, Fair Value	129,037
After one but within five years, Fair Value	161,034
After five but within ten years, Fair Value	83,391
More than ten years, Fair Value	5,283
Non-maturing, Fair Value	1,604
Total, Fair Value	$ 380,349	$ 404,623

Securities Available-for-Sale31

Securities Available-for-Sale - Continuous Unrealized Loss Position for 12 Months or Less and 12 Months or Longer (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	$ 49,847	$ 30,036
Less Than 12 Months, Unrealized Losses	136	67
12 Months or Longer, Fair Value	37,460	55,024
12 Months or Longer, Unrealized Losses	614	1,266
Total, Fair Value	87,307	85,060
Total, Unrealized Losses	750	1,333
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value		1,989
Less Than 12 Months, Unrealized Losses		10
12 Months or Longer, Fair Value	1,997
12 Months or Longer, Unrealized Losses	2
Total, Fair Value	1,997	1,989
Total, Unrealized Losses	2	10
Small Business Administration [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	1,799	1,031
Less Than 12 Months, Unrealized Losses	4	2
Total, Fair Value	1,799	1,031
Total, Unrealized Losses	4	2
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	46,435	26,519
Less Than 12 Months, Unrealized Losses	113	52
12 Months or Longer, Fair Value	29,009	49,341
12 Months or Longer, Unrealized Losses	80	248
Total, Fair Value	75,444	75,860
Total, Unrealized Losses	193	300
Privately Issued Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	429
Less Than 12 Months, Unrealized Losses	2
12 Months or Longer, Fair Value	471	490
12 Months or Longer, Unrealized Losses	17	13
Total, Fair Value	900	490
Total, Unrealized Losses	19	13
Obligations Issued by States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
12 Months or Longer, Fair Value	4,298	3,820
12 Months or Longer, Unrealized Losses	401	878
Total, Fair Value	4,298	3,820
Total, Unrealized Losses	401	878
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	1,184	497
Less Than 12 Months, Unrealized Losses	17	3
12 Months or Longer, Fair Value	1,685	1,373
12 Months or Longer, Unrealized Losses	114	127
Total, Fair Value	2,869	1,870
Total, Unrealized Losses	$ 131	$ 130

Investment Securities Held-to32

Investment Securities Held-to-Maturity - Summary of Held-to-Maturity Securities (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 1,412,702	$ 1,438,903
Gross Unrealized Gains	25,876	9,781
Gross Unrealized Losses	1,373	9,724
Estimated Fair Value	1,437,205	1,438,960
U.S. Government Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	152,732	186,734
Gross Unrealized Gains	3,033	2,234
Gross Unrealized Losses	11	141
Estimated Fair Value	155,754	188,827
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,259,970	1,252,169
Gross Unrealized Gains	22,843	7,547
Gross Unrealized Losses	1,362	9,583
Estimated Fair Value	$ 1,281,451	$ 1,250,133

Investment Securities Held-to33

Investment Securities Held-to-Maturity - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2016USD ($)Security	Dec. 31, 2015USD ($)Security
Schedule of Held-to-maturity Securities [Line Items]
Securities at fair value pledged to secure public deposits and repurchase agreements | $	$ 1,001,953,000	$ 1,004,743,000
Held-to-Maturity Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Weighted average remaining life of investment securities held-to-maturity	3 years 10 months 24 days
Number of securities, temporarily impaired for less than 12 months | Security	20	101
Number of securities, temporarily impaired for 12 months or longer | Security	24	26
Number of securities, temporarily impaired, total | Security	326	322
Held-to-Maturity Securities [Member] | U.S. Government Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Weighted average remaining life | $	$ 54,658,000
Federal Home Loan Bank Boston [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities pledged for borrowing at the Federal Home Loan Bank | $	$ 368,956,000	$ 432,965,000

Investment Securities Held-to34

Investment Securities Held-to-Maturity - Company's Securities Held-to-Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Within one year, Amortized Cost	$ 9,242
After one but within five years, Amortized Cost	1,205,411
After five but within ten years, Amortized Cost	193,283
More than ten years, Amortized Cost	4,766
Amortized Cost	1,412,702	$ 1,438,903
Within one year, Fair Value	9,343
After one but within five years, Fair Value	1,223,805
After five but within ten years, Fair Value	199,272
More than ten years, Fair Value	4,785
Estimated Fair Value	$ 1,437,205	$ 1,438,960

Investment Securities Held-to35

Investment Securities Held-to-Maturity - Unrealized Market Loss of Securities (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Held-to-maturity Securities [Line Items]
Less Than 12 Months, Fair Value	$ 111,760	$ 636,077
Less Than 12 Months, Unrealized Losses	390	6,798
12 Months or Longer, Fair Value	120,167	123,864
12 Months or Longer, Unrealized Losses	983	2,926
Total, Fair Value	231,927	759,941
Total, Unrealized Losses	1,373	9,724
U.S. Government Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Less Than 12 Months, Fair Value	19,990	9,859
Less Than 12 Months, Unrealized Losses	11	141
Total, Fair Value	19,990	9,859
Total, Unrealized Losses	11	141
U.S. Government Agency and Sponsored Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Less Than 12 Months, Fair Value	91,770	626,218
Less Than 12 Months, Unrealized Losses	379	6,657
12 Months or Longer, Fair Value	120,167	123,864
12 Months or Longer, Unrealized Losses	983	2,926
Total, Fair Value	211,937	750,082
Total, Unrealized Losses	$ 1,362	$ 9,583

Allowance for Loan Losses - Sum

Allowance for Loan Losses - Summary of Changes in Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Receivables [Abstract]
Allowance for loan losses, beginning of period	$ 23,075	$ 22,318
Loans charged off	(69)	(81)
Recoveries on loans previously charged-off	88	92
Net recoveries (charge-offs)	19	11
Provision charged to expense	450	200
Allowance for loan losses, end of period	$ 23,544	$ 22,529

Allowance for Loan Losses - S37

Allowance for Loan Losses - Summary of Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Allowance for loan losses:
Allowance for loan losses, beginning of period	$ 23,075	$ 22,318
Charge-offs	(69)	(81)
Recoveries	88	92
Provision	450	200
Allowance for loan losses, end of period	23,544	22,529
Amount of allowance for loan losses for loans deemed to be impaired	229	929
Amount of allowance for loan losses for loans not deemed to be impaired	23,315	21,600
Loans:
Total loans, net	1,762,458	1,341,330	$ 1,731,536
Loans deemed to be impaired	3,186	6,321
Loans not deemed to be impaired	1,759,272	1,335,009
Construction and Land Development [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	2,041	1,592
Provision	(68)	292
Allowance for loan losses, end of period	1,973	1,884
Amount of allowance for loan losses for loans deemed to be impaired	7	20
Amount of allowance for loan losses for loans not deemed to be impaired	1,966	1,864
Loans:
Total loans, net	26,572	25,347	27,421
Loans deemed to be impaired	98	102
Loans not deemed to be impaired	26,474	25,245
Commercial and Industrial [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	5,899	4,758
Recoveries	35	15
Provision	759	(128)
Allowance for loan losses, end of period	6,693	4,645
Amount of allowance for loan losses for loans deemed to be impaired	17	96
Amount of allowance for loan losses for loans not deemed to be impaired	6,676	4,549
Loans:
Total loans, net	529,168	157,637	452,235
Loans deemed to be impaired	429	871
Loans not deemed to be impaired	528,739	156,766
Municipal [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	994	1,488
Provision	(4)	(115)
Allowance for loan losses, end of period	990	1,373
Amount of allowance for loan losses for loans not deemed to be impaired	990	1,373
Loans:
Total loans, net	85,227	41,406	85,685
Loans not deemed to be impaired	85,227	41,406
Commercial Real Estate [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	10,589	11,199
Recoveries		2
Provision	(56)	(74)
Allowance for loan losses, end of period	10,533	11,127
Amount of allowance for loan losses for loans deemed to be impaired	89	631
Amount of allowance for loan losses for loans not deemed to be impaired	10,444	10,496
Loans:
Total loans, net	715,248	691,811	721,506
Loans deemed to be impaired	1,665	4,304
Loans not deemed to be impaired	713,583	687,507
Residential Real Estate [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	1,320	775
Recoveries	2	2
Provision	(73)	22
Allowance for loan losses, end of period	1,249	799
Amount of allowance for loan losses for loans deemed to be impaired	27	90
Amount of allowance for loan losses for loans not deemed to be impaired	1,222	709
Loans:
Total loans, net	215,040	258,558	255,346
Loans deemed to be impaired	905	952
Loans not deemed to be impaired	214,135	257,606
Consumer [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	644	810
Charge-offs	(69)	(81)
Recoveries	51	73
Provision	67	(88)
Allowance for loan losses, end of period	693	714
Amount of allowance for loan losses for loans not deemed to be impaired	693	714
Loans:
Total loans, net	12,826	10,508	11,323
Loans not deemed to be impaired	12,826	10,508
Home Equity [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	1,077	599
Provision	108	15
Allowance for loan losses, end of period	1,185	614
Amount of allowance for loan losses for loans deemed to be impaired	89	92
Amount of allowance for loan losses for loans not deemed to be impaired	1,096	522
Loans:
Total loans, net	178,377	156,063	$ 178,020
Loans deemed to be impaired	89	92
Loans not deemed to be impaired	178,288	155,971
Unallocated [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	511	1,097
Provision	(283)	276
Allowance for loan losses, end of period	228	1,373
Amount of allowance for loan losses for loans not deemed to be impaired	$ 228	$ 1,373

Allowance for Loan Losses - Loa

Allowance for Loan Losses - Loans by Risk Rating (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Loans by risk rating
Financing Receivable, Net	$ 1,762,458	$ 1,731,536	$ 1,341,330
Construction and Land Development [Member]
Loans by risk rating
Financing Receivable, Net	26,572	27,421	25,347
Construction and Land Development [Member] | 1-3 (Pass) [Member]
Loans by risk rating
Financing Receivable, Net	19,492	20,281
Construction and Land Development [Member] | 4 (Monitor) [Member]
Loans by risk rating
Financing Receivable, Net	6,982	7,042
Construction and Land Development [Member] | Impaired [Member]
Loans by risk rating
Financing Receivable, Net	98	98
Commercial and Industrial [Member]
Loans by risk rating
Financing Receivable, Net	529,168	452,235	157,637
Commercial and Industrial [Member] | 1-3 (Pass) [Member]
Loans by risk rating
Financing Receivable, Net	528,721	451,774
Commercial and Industrial [Member] | 4 (Monitor) [Member]
Loans by risk rating
Financing Receivable, Net	18	18
Commercial and Industrial [Member] | Impaired [Member]
Loans by risk rating
Financing Receivable, Net	429	443
Municipal [Member]
Loans by risk rating
Financing Receivable, Net	85,227	85,685	41,406
Municipal [Member] | 1-3 (Pass) [Member]
Loans by risk rating
Financing Receivable, Net	85,227	85,685
Commercial Real Estate [Member]
Loans by risk rating
Financing Receivable, Net	715,248	721,506	$ 691,811
Commercial Real Estate [Member] | 1-3 (Pass) [Member]
Loans by risk rating
Financing Receivable, Net	712,671	718,911
Commercial Real Estate [Member] | 4 (Monitor) [Member]
Loans by risk rating
Financing Receivable, Net	912	917
Commercial Real Estate [Member] | Impaired [Member]
Loans by risk rating
Financing Receivable, Net	$ 1,665	$ 1,678

Allowance for Loan Losses - L39

Allowance for Loan Losses - Loans by Credit Ratings Issued by National Organizations (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	$ 838,107	$ 765,695
Aaa - Aa3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	352,640	306,145
A1 - A3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	305,301	278,691
Baa1 - Baa3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	175,686	176,379
Ba2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	4,480	4,480
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	449,311	375,152
Commercial and Industrial [Member] | Aaa - Aa3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	281,922	234,733
Commercial and Industrial [Member] | A1 - A3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	167,389	140,419
Municipal [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	84,177	84,635
Municipal [Member] | Aaa - Aa3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	63,407	63,865
Municipal [Member] | A1 - A3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	7,400	7,400
Municipal [Member] | Baa1 - Baa3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	8,890	8,890
Municipal [Member] | Ba2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	4,480	4,480
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	304,619	305,908
Commercial Real Estate [Member] | Aaa - Aa3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	7,311	7,547
Commercial Real Estate [Member] | A1 - A3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	130,512	130,872
Commercial Real Estate [Member] | Baa1 - Baa3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	$ 166,796	$ 167,489

Allowance for Loan Losses - Agi

Allowance for Loan Losses - Aging of Past Due Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Accruing 30-89 Days Past Due	$ 4,093	$ 2,692
Non Accrual	1,490	2,336
Total Past Due	5,583	5,028
Current Loans	1,756,875	1,726,508
Total loans, net	1,762,458	1,731,536	$ 1,341,330
Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Non Accrual	98	99
Total Past Due	98	99
Current Loans	26,474	27,322
Total loans, net	26,572	27,421	25,347
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Accruing 30-89 Days Past Due	226
Non Accrual	56	60
Total Past Due	282	60
Current Loans	528,886	452,175
Total loans, net	529,168	452,235	157,637
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current Loans	85,227	85,685
Total loans, net	85,227	85,685	41,406
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Accruing 30-89 Days Past Due	2,290	1,462
Non Accrual	168	174
Total Past Due	2,458	1,636
Current Loans	712,790	719,870
Total loans, net	715,248	721,506	691,811
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Accruing 30-89 Days Past Due	1,037	596
Non Accrual	1,036	1,559
Total Past Due	2,073	2,155
Current Loans	212,967	253,191
Total loans, net	215,040	255,346	258,558
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Accruing 30-89 Days Past Due	1	6
Non Accrual	6
Total Past Due	7	6
Current Loans	12,819	11,317
Total loans, net	12,826	11,323	10,508
Home Equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Accruing 30-89 Days Past Due	539	628
Non Accrual	126	444
Total Past Due	665	1,072
Current Loans	177,712	176,948
Total loans, net	$ 178,377	$ 178,020	$ 156,063

Allowance for Loan Losses - Inf

Allowance for Loan Losses - Information Pertaining to Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Carrying Value	$ 165	$ 587
With no required reserve recorded, Unpaid Principal Balance	438	716
With no required reserve recorded, Required Reserve	0	0
With no required reserve recorded, Average Carrying Value Recognized	169	566
With no required reserve recorded, Interest Income	2	2
With required reserve recorded, Carrying Value	3,021	5,734
With required reserve recorded, Unpaid Principal Balance	3,145	6,036
With required reserve recorded, Required Reserve	229	929
With required reserve recorded, Average Carrying Value Recognized	3,036	5,757
With required reserve recorded, Interest Income	20	33
Carrying Value	3,186	6,321
Unpaid Principal Balance	3,583	6,752
With required reserve recorded, Required Reserve	229	929
Average Carrying Value Recognized	3,205	6,323
Interest Income	22	35
Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Required Reserve	0	0
With required reserve recorded, Carrying Value	98	102
With required reserve recorded, Unpaid Principal Balance	108	108
With required reserve recorded, Required Reserve	7	20
With required reserve recorded, Average Carrying Value Recognized	98	103
Carrying Value	98	102
Unpaid Principal Balance	108	108
With required reserve recorded, Required Reserve	7	20
Average Carrying Value Recognized	98	103
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Carrying Value	56	63
With no required reserve recorded, Unpaid Principal Balance	243	105
With no required reserve recorded, Required Reserve	0	0
With no required reserve recorded, Average Carrying Value Recognized	58	39
With required reserve recorded, Carrying Value	373	808
With required reserve recorded, Unpaid Principal Balance	388	1,010
With required reserve recorded, Required Reserve	17	96
With required reserve recorded, Average Carrying Value Recognized	378	821
With required reserve recorded, Interest Income	5	11
Carrying Value	429	871
Unpaid Principal Balance	631	1,115
With required reserve recorded, Required Reserve	17	96
Average Carrying Value Recognized	436	860
Interest Income	5	11
Municipal [Member] | Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Required Reserve	0	0
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Carrying Value		392
With no required reserve recorded, Unpaid Principal Balance		396
With no required reserve recorded, Required Reserve	0	0
With no required reserve recorded, Average Carrying Value Recognized		393
With required reserve recorded, Carrying Value	1,665	3,912
With required reserve recorded, Unpaid Principal Balance	1,763	4,006
With required reserve recorded, Required Reserve	89	631
With required reserve recorded, Average Carrying Value Recognized	1,671	3,918
With required reserve recorded, Interest Income	15	16
Carrying Value	1,665	4,304
Unpaid Principal Balance	1,763	4,402
With required reserve recorded, Required Reserve	89	631
Average Carrying Value Recognized	1,671	4,311
Interest Income	15	16
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Carrying Value	109	132
With no required reserve recorded, Unpaid Principal Balance	195	215
With no required reserve recorded, Required Reserve	0	0
With no required reserve recorded, Average Carrying Value Recognized	111	134
With no required reserve recorded, Interest Income	2	2
With required reserve recorded, Carrying Value	796	820
With required reserve recorded, Unpaid Principal Balance	797	820
With required reserve recorded, Required Reserve	27	90
With required reserve recorded, Average Carrying Value Recognized	799	823
With required reserve recorded, Interest Income		6
Carrying Value	905	952
Unpaid Principal Balance	992	1,035
With required reserve recorded, Required Reserve	27	90
Average Carrying Value Recognized	910	957
Interest Income	2	8
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Required Reserve	0	0
Home Equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Required Reserve	0	0
With required reserve recorded, Carrying Value	89	92
With required reserve recorded, Unpaid Principal Balance	89	92
With required reserve recorded, Required Reserve	89	92
With required reserve recorded, Average Carrying Value Recognized	90	92
Carrying Value	89	92
Unpaid Principal Balance	89	92
With required reserve recorded, Required Reserve	89	92
Average Carrying Value Recognized	$ 90	$ 92

Allowance for Loan Losses - Add

Allowance for Loan Losses - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Receivables [Abstract]
Troubled debt restructurings, subsequently defaulted	$ 0	$ 0

Reclassifications Out of Accu43

Reclassifications Out of Accumulated Other Comprehensive Income - Reclassifications Out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Provision for income taxes	$ (64)	$ (215)
Net income	5,307	4,959
Salaries and employee benefits	(9,776)	(9,134)
Reclassification Out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income	(1,226)	(948)
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 securities	(1,511)	(1,129)
Provision for income taxes	527	394
Net income	(984)	(735)
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	(2)	(3)
Reclassification Out of Accumulated Other Comprehensive Income [Member] | Actuarial Gains (Losses) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	(401)	(352)
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	(403)	(355)
Provision for income taxes	161	142
Net income	$ (242)	$ (213)

Earnings per Share ("EPS") - Ad

Earnings per Share ("EPS") - Additional Information (Detail) - Class A Common Stock [Member] - shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Number of Stock options outstanding	0	0
Minimum [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Class A common stock entitled dividend per share percent in comparison to Class B common stock	200.00%

Earnings Per Share ("EPS") - Re

Earnings Per Share ("EPS") - Reconciliation of Basic EPS and Diluted EPS (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 5,307	$ 4,959
Class A Common Stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 4,168	$ 3,895
Weighted average shares outstanding, basic	3,600,729	3,600,729
Basic earnings per share	$ 1.16	$ 1.08
Weighted average shares outstanding, diluted	5,567,909	5,567,909
Diluted earnings per share	$ 0.95	$ 0.89
Class B Common Stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 1,139	$ 1,064
Weighted average shares outstanding, basic	1,967,180	1,967,180
Basic earnings per share	$ 0.58	$ 0.54
Weighted average shares outstanding, diluted	1,967,180	1,967,180
Diluted earnings per share	$ 0.58	$ 0.54

Employee Benefits - Additional

Employee Benefits - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2016USD ($)
Compensation and Retirement Disclosure [Abstract]
Number of years service to participate in supplemental plan	1 year
Current fiscal year contribution to pension plan	$ 1,325,000
Employer expected contribution to Pension Plan in 2015	$ 2,075,000

Employee Benefits - Components

Employee Benefits - Components of Net Periodic Benefit Cost (Credit) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 318	$ 336
Interest	340	394
Expected return on plan assets	(694)	(688)
Recognized prior service cost (benefit)	(26)	(26)
Recognized net actuarial losses	200	203
Net periodic benefit (credit) cost	138	219
Supplemental Insurance/ Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	455	397
Interest	334	341
Recognized prior service cost (benefit)	29	29
Recognized net actuarial losses	200	150
Net periodic benefit (credit) cost	$ 1,018	$ 917

Fair Value Measurements - Finan

Fair Value Measurements - Financial Instruments Measured at Fair Value on a Recurring and Non-recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	$ 380,349	$ 404,623
Fair Value Measurements, Level 1 Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	217	215
Fair Value Measurements, Level 2 Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	245,043	247,411
Fair Value Measurements, Level 3 Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	135,089	156,997
Financial Instruments Measured at Fair Value on a Non-recurring Basis
Impaired Loans	1,044	1,056
U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	1,997	1,989
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	1,997	1,989
Small Business Administration [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	5,931	5,989
Small Business Administration [Member] | Fair Value Measurements, Level 2 Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	5,931	5,989
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	226,293	233,526
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	226,293	233,526
Privately Issued Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	1,345	1,434
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	1,345	1,434
Obligations Issued by States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	135,089	156,960
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	135,089	156,960
Other Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	4,469	4,473
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	4,469	4,473
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	217	252
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	217	215
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		37
U.S. Government Sponsored Enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	5,008
U.S. Government Sponsored Enterprises [Member] | Fair Value Measurements, Level 2 Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	5,008
Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	380,349	404,623
Financial Instruments Measured at Fair Value on a Non-recurring Basis
Impaired Loans	1,044	1,056
Carrying Value [Member] | U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	1,997	1,989
Carrying Value [Member] | Small Business Administration [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	5,931	5,989
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	226,293	233,526
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	1,345	1,434
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	135,089	156,960
Carrying Value [Member] | Other Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	4,469	4,473
Carrying Value [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	217	$ 252
Carrying Value [Member] | U.S. Government Sponsored Enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	$ 5,008

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Specific adjustments to impaired loans recognized	$ (14,000)	$ 165,000
Transfers between level 1, 2 and 3	0
Liabilities measured at fair value on a recurring or nonrecurring basis	0
Transfers between level 1, 2 and 3		0
Liabilities measured at fair value on a recurring or nonrecurring basis		$ 0
Fair Value Measurements, Level 3 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized cost of Level 3 securities	135,490,000		$ 119,750,000
Unrealized loss	$ 401,000		$ 875,000

Fair Value Measurements - Asset

Fair Value Measurements - Assets Measured at Fair Value (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Securities AFS [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Fair Value	$ 135,089	$ 156,997
Valuation Technique	Discounted cash flow
Unobservable Input	Discount rate
Impaired Loans [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Fair Value	$ 1,044	$ 1,056
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%	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%	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%	1.00%
Maximum [Member] | Impaired Loans [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Unobservable Input Value or Range	30.00%	30.00%

Fair Value Measurements - Ass51

Fair Value Measurements - Assets Measured at Fair Value (Parenthetical) (Detail)	3 Months Ended
	Mar. 31, 2016
Municipal [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Securities maturity period	one year or less

Fair Value Measurements - Chang

Fair Value Measurements - Changes in Level 3 Securities (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 156,997	$ 96,886
Purchases	15,935	41,909
Maturities and calls	(38,288)	(19,914)
Amortization	(33)	(6)
Changes in fair value	478
Ending Balance	135,089	118,875
Auction Rate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	3,820	3,820
Changes in fair value	478
Ending Balance	4,298	3,820
Obligations Issued by States and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	153,140	92,964
Purchases	15,935	41,909
Maturities and calls	(38,251)	(19,914)
Amortization	(33)	(6)
Ending Balance	130,791	114,953
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	37	102
Maturities and calls	$ (37)
Ending Balance		$ 102

Fair Values of Financial Inst53

Fair Values of Financial Instruments - Carrying Amount and Fair Value of Company's Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financial assets:
Securities held-to-maturity	$ 1,412,702	$ 1,438,903
Loans Held-for-Sale	48,180
Loans	1,738,914	1,708,461
Financial liabilities:
Time deposits	446,185	473,426
Other borrowed funds	356,000	368,000
Subordinated debentures	36,083	36,083
Carrying Value [Member]
Financial assets:
Securities held-to-maturity	1,412,702	1,438,903
Loans Held-for-Sale	48,180
Loans	1,738,914	1,708,461
Financial liabilities:
Time deposits	446,185	473,426
Other borrowed funds	356,000	368,000
Subordinated debentures	36,083	36,083
Estimated Fair Value [Member]
Financial assets:
Securities held-to-maturity	1,437,205	1,438,960
Loans Held-for-Sale	48,958
Loans	1,750,498	1,677,270
Financial liabilities:
Time deposits	448,690	474,046
Other borrowed funds	365,342	372,209
Subordinated debentures	36,083	36,083
Fair Value Measurements, Level 2 Inputs [Member]
Financial assets:
Securities held-to-maturity	1,437,205	1,438,960
Loans Held-for-Sale	48,958
Financial liabilities:
Time deposits	448,690	474,046
Other borrowed funds	365,342	372,209
Fair Value Measurements, Level 3 Inputs [Member]
Financial assets:
Loans	1,750,498	1,677,270
Financial liabilities:
Subordinated debentures	$ 36,083	$ 36,083