Century Bancorp (CNBKA) 10-Q 8 Aug 17 2017 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2017	Jul. 31, 2017
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q2
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		3,603,729
Class B Common Stock [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		1,964,180

Consolidated Balance Sheets (un

Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Assets
Cash and due from banks	$ 74,787	$ 62,400
Federal funds sold and interest-bearing deposits in other banks	153,374	173,751
Total cash and cash equivalents	228,161	236,151
Short-term investments		3,183
Securities available-for-sale, amortized cost $411,709 and $500,220, respectively	411,340	499,297
Securities held-to-maturity, fair value $1,706,840 and $ 1,635,808, respectively	1,722,875	1,653,986
Federal Home Loan Bank of Boston, stock at cost	25,588	21,042
Loans, net:
Construction and land development	14,159	14,928
Commercial and industrial	650,542	612,503
Municipal	127,259	135,418
Commercial real estate	736,603	696,173
Residential real estate	264,744	241,357
Home equity	229,274	211,857
Overdrafts	518	684
Total loans, net	2,033,799	1,923,933
Less: allowance for loan losses	25,289	24,406
Net loans	2,008,510	1,899,527
Bank premises and equipment	23,177	23,417
Accrued interest receivable	10,309	9,645
Goodwill	2,714	2,714
Other assets	116,563	113,646
Total assets	4,549,237	4,462,608
Deposits:
Demand deposits	687,219	689,286
Savings and NOW deposits	1,409,327	1,304,394
Money market accounts	897,241	1,181,179
Time deposits	575,410	478,359
Total deposits	3,569,197	3,653,218
Securities sold under agreements to repurchase	167,340	182,280
Other borrowed funds	455,500	293,000
Subordinated debentures	36,083	36,083
Due to broker	6,854
Other liabilities	59,638	57,986
Total liabilities	4,294,612	4,222,567
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	256,718	243,565
Stockholders' equity before adjustment of accumulated other comprehensive income (loss)	274,578	261,425
Unrealized losses on securities available-for-sale, net of taxes	(234)	(567)
Unrealized losses on securities transferred to held-to-maturity, net of taxes	(3,451)	(4,084)
Pension liability, net of taxes	(16,268)	(16,733)
Total accumulated other comprehensive loss, net of taxes	(19,953)	(21,384)
Total stockholders' equity	254,625	240,041
Total liabilities and stockholders' equity	4,549,237	4,462,608
Consumer [Member]
Loans, net:
Consumer	10,700	11,013
Total loans, net	11,218	11,697
Less: allowance for loan losses	195	582
Class A Common Stock [Member]
Stockholders' Equity
Common stock value	3,604	3,601
Total stockholders' equity	3,604	3,601
Class B Common Stock [Member]
Stockholders' Equity
Common stock value	1,964	1,967
Total stockholders' equity	$ 1,964	$ 1,967

Consolidated Balance Sheets (u3

Consolidated Balance Sheets (unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Amortized cost	$ 411,709	$ 500,220
Held-to-maturity securities, fair value	$ 1,706,840	$ 1,635,808
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	3,603,729	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	1,964,180	1,967,180

Consolidated Statements of Inco

Consolidated Statements of Income (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Interest income
Loans	$ 16,910	$ 14,163	$ 32,010	$ 28,335
Securities held-to-maturity	9,824	8,128	19,359	15,940
Securities available-for-sale	1,723	1,143	3,334	2,107
Federal funds sold and interest-bearing deposits in other banks	349	308	742	623
Total interest income	28,806	23,742	55,445	47,005
Interest expense
Savings and NOW deposits	1,500	938	2,727	1,776
Money market accounts	1,234	781	2,508	1,576
Time deposits	1,902	1,394	3,553	2,752
Securities sold under agreements to repurchase	120	126	223	241
Other borrowed funds and subordinated debentures	1,945	2,247	3,873	4,554
Total interest expense	6,701	5,486	12,884	10,899
Net interest income	22,105	18,256	42,561	36,106
Provision for loan losses	490	350	890	800
Net interest income after provision for loan losses	21,615	17,906	41,671	35,306
Other operating income
Service charges on deposit accounts	2,074	1,962	4,090	3,899
Lockbox fees	861	883	1,632	1,672
Net gains on sales of securities		45		45
Gains on sales of mortgage loans	269	798	370	798
Other income	1,087	955	2,108	1,883
Total other operating income	4,291	4,643	8,200	8,297
Operating expenses
Salaries and employee benefits	10,719	10,040	21,862	19,816
Occupancy	1,495	1,551	3,236	3,130
Equipment	757	679	1,463	1,315
FDIC assessments	440	592	878	1,160
Other	3,786	3,426	7,483	6,549
Total operating expenses	17,197	16,288	34,922	31,970
Income before income taxes	8,709	6,261	14,949	11,633
Provision for income taxes	552	20	696	84
Net income	$ 8,157	$ 6,241	$ 14,253	$ 11,549
Class A Common Stock [Member]
Share data:
Weighted average number of shares outstanding, basic	3,603,729	3,600,729	3,602,229	3,600,729
Weighted average number of shares outstanding, diluted	5,567,909	5,567,909	5,567,909	5,567,909
Basic earnings per share	$ 1.78	$ 1.36	$ 3.11	$ 2.52
Diluted earnings per share	$ 1.47	$ 1.12	$ 2.56	$ 2.07
Class B Common Stock [Member]
Share data:
Weighted average number of shares outstanding, basic	1,964,180	1,967,180	1,965,680	1,967,180
Weighted average number of shares outstanding, diluted	1,964,180	1,967,180	1,965,680	1,967,180
Basic earnings per share	$ 0.89	$ 0.68	$ 1.55	$ 1.26
Diluted earnings per share	$ 0.89	$ 0.68	$ 1.55	$ 1.26

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 8,157	$ 6,241	$ 14,253	$ 11,549
Unrealized gains (losses) on securities:
Unrealized (losses) gains arising during period	198	(325)	333	(11)
Less: reclassification adjustment for gains included in net income		(27)		(27)
Total unrealized (losses) gains on securities	198	(352)	333	(38)
Accretion of net unrealized losses transferred	260	762	633	1,747
Defined benefit pension plans:
Amortization of prior service cost and loss included in net periodic benefit cost	233	243	465	485
Other comprehensive income	691	653	1,431	2,194
Comprehensive income	$ 8,848	$ 6,894	$ 15,684	$ 13,743

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 Income (Loss) [Member]
Beginning balance at Dec. 31, 2015	$ 214,544	$ 3,601	$ 1,967	$ 12,292	$ 221,232			$ (24,548)
Net income	11,549				11,549
Other comprehensive income, net of tax:
Unrealized holding (losses) gains arising during period, net of taxes	(38)							(38)
Accretion of unrealized losses on securities transferred to held-to-maturity, net of taxes	1,747							1,747
Pension liability adjustment, net of taxes	485							485
Cash dividends						$ (866)	$ (235)
Ending balance at Jun. 30, 2016	227,186	3,601	1,967	12,292	231,680			(22,354)
Beginning balance at Dec. 31, 2016	240,041	3,601	1,967	12,292	243,565			(21,384)
Net income	14,253				14,253
Other comprehensive income, net of tax:
Unrealized holding (losses) gains arising during period, net of taxes	333							333
Accretion of unrealized losses on securities transferred to held-to-maturity, net of taxes	633							633
Pension liability adjustment, net of taxes	465							465
Conversion of Class B Common Stock to Class A Common Stock		3	(3)
Cash dividends						$ (865)	$ (235)
Ending balance at Jun. 30, 2017	$ 254,625	$ 3,604	$ 1,964	$ 12,292	$ 256,718			$ (19,953)

Consolidated Statements of Cha7

Consolidated Statements of Changes in Stockholders' Equity (unaudited) (Parenthetical) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Unrealized holding (losses) gains arising during period, taxes	$ 221	$ 61
Realized net gains		45
Accretion of net unrealized losses transferred during the period, taxes	690	935
Pension liability adjustment, taxes	$ 311	$ 322
Class A Common Stock [Member]
Conversion of Class B Common Stock to Class A Common Stock, shares	3,000
Cash dividends, per share	$ 0.24	$ 0.24
Class B Common Stock [Member]
Conversion of Class B Common Stock to Class A Common Stock, shares	3,000
Cash dividends, per share	$ 0.12	$ 0.12

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 14,253	$ 11,549
Adjustments to reconcile net income to net cash (used in) provided by operating activities:
Gain on sales of mortgage loans	(370)	(798)
Net gains on sales of securities		(45)
Provision for loan losses	890	800
Deferred income taxes	(1,579)	(1,792)
Net depreciation and amortization	1,660	1,575
Decrease in accrued interest receivable	(664)	(712)
Increase in other assets	(2,593)	(3,428)
Increase in other liabilities	2,426	1,069
Net cash provided by operating activities	14,023	8,218
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of short-term investments		(8)
Maturities of short-term investments	3,183
Proceeds from redemptions of Federal Home Loan Bank of Boston stock	714	4,898
Purchase of Federal Home Loan Bank of Boston stock	(5,260)	(2,177)
Proceeds from calls/maturities of securities available-for-sale	166,976	130,513
Proceeds from sales of securities available-for-sale	0	1,946
Purchase of securities available-for-sale	(71,793)	(287,834)
Proceeds from calls/maturities of securities held-to-maturity	153,405	213,337
Proceeds from sales of securities held-to-maturity	0	192
Purchase of securities held-to-maturity	(220,832)	(345,692)
Net increase in loans	(136,181)	(132,182)
Proceeds from sales of portfolio loans	26,701	50,220
Capital expenditures	(1,365)	(835)
Net cash used in investing activities	(84,452)	(367,622)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net increase (decrease) in time deposits	97,051	(12,899)
Net (decrease) increase in demand, savings, money market and NOW deposits	(181,072)	156,771
Cash dividends	(1,100)	(1,101)
Net (decrease) increase in securities sold under agreements to repurchase	(14,940)	19,915
Net increase in other borrowed funds	162,500	63,000
Net cash provided by financing activities	62,439	225,686
Net decrease in cash and cash equivalents	(7,990)	(133,718)
Cash and cash equivalents at beginning of period	236,151	220,724
Cash and cash equivalents at end of period	228,161	87,006
Cash paid during the period for:
Interest	12,997	10,893
Income taxes	2,980	2,110
Change in unrealized gains (losses) on securities available-for-sale, net of taxes	333	(38)
Change in unrealized losses on securities transferred to held-to-maturity, net of taxes	633	1,747
Pension liability adjustment, net of taxes	465	485
Change in due to (from) to broker	$ 6,854	3,180
Transfer of loans to loans held-for-sale		$ 12,403

Basis of Financial Statement Pr

Basis of Financial Statement Presentation	6 Months Ended
	Jun. 30, 2017
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, New Hampshire, Rhode Island, Connecticut, and New York. 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 10-K 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

Securities Available-for-Sale

Securities Available-for-Sale	6 Months Ended
	Jun. 30, 2017
Text Block [Abstract]
Securities Available-for-Sale	Note 2. Securities Available-for-Sale June 30, 2017 December 31, 2016 Amortized Gross Gross Fair Value Amortized Gross Gross Fair (in thousands) U.S. Treasury $ 1,999 $ — $ 4 $ 1,995 $ 2,000 $ — $ — $ 2,000 U.S. Government Sponsored Enterprises 10,000 — — 10,000 25,000 — 48 24,952 SBA Backed Securities 71,357 27 195 71,189 57,899 14 146 57,767 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 223,655 463 336 223,782 243,703 293 671 243,325 Privately Issued Residential Mortgage-Backed Securities 1,025 3 13 1,015 1,121 2 14 1,109 Obligations Issued by States and Political Subdivisions 98,457 — 408 98,049 165,281 — 405 164,876 Other Debt Securities 5,100 85 193 4,992 5,100 18 194 4,924 Equity Securities 116 202 — 318 116 228 — 344 Total $ 411,709 $ 780 $ 1,149 $ 411,340 $ 500,220 $ 555 $ 1,478 $ 499,297 Included in SBA Backed Securities and 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 $ 173,235,000 and $210,780,000 at June 30, 2017 and December 31, 2016, respectively. Also included in securities available-for-sale available-for-sale available-for-sales Debt securities of U.S. Government Sponsored Enterprises and U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 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 Amortized Fair Value (in thousands) Within one year $ 90,264 $ 90,255 After one but within five years 132,716 132,786 After five but within ten years 105,344 105,360 More than 10 years 81,769 81,270 Non-maturing 1,616 1,669 Total $ 411,709 $ 411,340 The weighted average remaining life of investment securities available-for-sale As of June 30, 2017 and December 31, 2016, 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 unrealized loss on SBA Backed Securities, U.S. Government Agency and Sponsored Enterprise Mortgage Backed Securities, Obligations Issued by States and Political Subdivisions, and Other Debt 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 June 30, 2017 Less than 12 months 12 months or longer Total Temporarily Impaired Investments Fair Unrealized Fair Unrealized Fair Value Unrealized (in thousands) U.S. Treasury $ 1,995 $ 4 $ — $ — $ 1,995 $ 4 U.S. Government Sponsored Enterprises — — — — — — SBA Backed Securities 27,850 116 17,775 79 45,625 195 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 36,251 83 66,121 253 102,372 336 Privately Issued Residential Mortgage-Backed Securities — — 707 13 707 13 Obligations Issued by States and Political Subdivisions — — 4,297 408 4,297 408 Other Debt Securities — — 1,907 193 1,907 193 Total temporarily impaired securities $ 66,096 $ 203 $ 90,807 $ 946 $ 156,903 $ 1,149 The following table shows the temporarily impaired securities of the Company’s available-for-sale Temporarily Impaired Investments December 31, 2016 Less than 12 months 12 months or longer Total Fair Value Unrealized Fair Unrealized Fair Value Unrealized (in thousands) U.S. Government Sponsored Enterprises $ 24,952 $ 48 $ — $ — $ 24,952 $ 48 SBA Backed Securities 52,346 145 951 1 53,297 146 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 135,612 485 31,504 186 167,116 671 Privately Issued Residential Mortgage-Backed Securities — — 757 14 757 14 Obligations Issued by States and Political Subdivisions — — 4,298 405 4,298 405 Other Debt Securities 453 47 1,553 147 2,006 194 Total temporarily impaired securities $ 213,363 $ 725 $ 39,063 $ 753 $ 252,426 $ 1,478

Investment Securities Held-to-M

Investment Securities Held-to-Maturity	6 Months Ended
	Jun. 30, 2017
Text Block [Abstract]
Investment Securities Held-to-Maturity	Note 3. Investment Securities Held-to-Maturity June 30, 2017 December 31, 2016 Amortized Gross Gross Estimated Amortized Gross Gross Estimated (in thousands) U.S. Government Sponsored Enterprises $ 134,378 $ 931 $ 287 $ 135,022 $ 148,326 $ 1,066 $ 527 $ 148,865 SBA Backed Securities 54,427 3 779 53,651 46,140 — 1,088 45,052 U.S. Government Agency and Sponsored Enterprises Mortgage-Backed Securities 1,534,070 5,419 21,322 1,518,167 1,459,520 4,948 22,577 1,441,891 Total $ 1,722,875 $ 6,353 $ 22,388 $ 1,706,840 $ 1,653,986 $ 6,014 $ 24,192 $ 1,635,808 Included in U.S. Government and Agency Securities are securities pledged to secure public deposits and repurchase agreements at fair value amounting to $1,268,349,000 and $1,147,207,000 at June 30, 2017 and December 31, 2016, respectively. Also included are securities pledged for borrowing at the Federal Home Loan Bank of Boston at fair value amounting to $305,269,000 and $424,353,000 at June 30, 2017 and December 31, 2016, respectively. There were no sales of held-to-maturity held-to-maturity held-to-maturity At June 30, 2017 and December 31, 2016, all mortgage-backed securities are obligations of U.S. Government Agencies and Government Sponsored Enterprises. Debt securities of U.S. Government Sponsored Enterprises and U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 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 Amortized Fair Value (in thousands) Within one year $ 45,780 $ 45,827 After one but within five years 1,224,104 1,213,863 After five but within ten years 449,698 444,027 More than ten years 3,293 3,123 Total $ 1,722,875 $ 1,706,840 The weighted average remaining life of investment securities held-to-maturity As of June 30, 2017 and December 31, 2016, 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, SBA Backed Securities, and U.S. Government Agency and Sponsored Enterprise 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 June 30, 2017 and December 31, 2016. 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 June 30, 2017 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 $ 45,209 $ 287 $ — $ — $ 45,209 $ 287 SBA Backed Securities 50,633 779 — — 50,633 779 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 1,015,890 18,964 76,584 2,358 1,092,474 21,322 Total temporarily impaired securities $ 1,111,732 $ 20,030 $ 76,584 $ 2,358 $ 1,188,316 $ 22,388 The following table shows the temporarily impaired securities of the Company’s held-to-maturity December 31, 2016 Less Than 12 Months 12 Months or Longer Total Temporarily Impaired Investments Fair Unrealized Fair Unrealized Fair Unrealized (in thousands) U.S. Government Sponsored Enterprises $ 59,219 $ 527 $ — $ — $ 59,219 $ 527 SBA Backed Securities 45,052 1,088 — — 45,052 1,088 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 1,008,960 20,725 58,535 1,852 1,067,495 22,577 Total temporarily impaired securities $ 1,113,231 $ 22,340 $ 58,535 $ 1,852 $ 1,171,766 $ 24,192

Allowance for Loan Losses

Allowance for Loan Losses	6 Months Ended
	Jun. 30, 2017
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 Six months ended 2017 2016 2017 2016 (in thousands) Allowance for loan losses, beginning of period $ 24,827 $ 23,544 $ 24,406 $ 23,075 Adjustment — (84 ) — (84 ) Loans charged off (100 ) (111 ) (197 ) (180 ) Recoveries on loans previously charged-off 72 164 190 252 Net (charge-offs) / recoveries (28 ) 53 (7 ) 72 Provision charged to expense 490 350 890 800 Allowance for loan losses, end of period $ 25,289 $ 23,863 $ 25,289 $ 23,863 Further information pertaining to the allowance for loan losses for the three months ending June 30, 2017 follows: Construction Commercial Municipal Commercial Residential Consumer Home Unallocated Total (in thousands) Allowance for loan losses: Balance at March 31, 2017 $ 873 $ 7,369 $ 1,899 $ 11,216 $ 1,671 $ 452 $ 1,050 $ 297 $ 24,827 Charge-offs — (29 ) — — — (71 ) — — (100 ) Recoveries — 34 — — — 38 — — 72 Provision 264 189 (40 ) (188 ) 447 (224 ) 96 (54 ) 490 Ending balance at June 30, 2017 $ 1,137 $ 7,563 $ 1,859 $ 11,028 $ 2,118 $ 195 $ 1,146 $ 243 $ 25,289 Amount of allowance for loan losses for loans deemed to be impaired $ — $ 11 $ — $ 120 $ 69 $ — $ — $ — $ 200 Amount of allowance for loan losses for loans not deemed to be impaired $ 1,137 $ 7,552 $ 1,859 $ 10,908 $ 2,049 $ 195 $ 1,146 $ 243 $ 25,089 Loans: Ending balance $ 14,159 $ 650,542 $ 127,259 $ 736,603 $ 264,744 $ 11,218 $ 229,274 $ — $ 2,033,799 Loans deemed to be impaired $ — $ 365 $ — $ 2,603 $ 4,343 $ — $ — $ — $ 7,311 Loans not deemed to be impaired $ 14,159 $ 650,177 $ 127,259 $ 734,000 $ 260,401 $ 11,218 $ 229,274 $ — $ 2,026,488 Further information pertaining to the allowance for loan losses for the six months ending June 30, 2017 follows: Construction Commercial Municipal Commercial Residential Consumer Home Unallocated Total (in thousands) Allowance for loan losses: Balance at December 31, 2016 $ 1,012 $ 6,972 $ 1,612 $ 11,135 $ 1,698 $ 582 $ 1,102 $ 293 $ 24,406 Charge-offs — (29 ) — — — (168 ) — — (197 ) Recoveries — 54 — — 2 134 — — 190 Provision 125 566 247 (107 ) 418 (353 ) 44 (50 ) 890 Ending balance at June 30, 2017 $ 1,137 $ 7,563 $ 1,859 $ 11,028 $ 2,118 $ 195 $ 1,146 $ 243 $ 25,289 Amount of allowance for loan losses for loans deemed to be impaired $ — $ 11 $ — $ 120 $ 69 $ — $ — $ — $ 200 Amount of allowance for loan losses for loans not deemed to be impaired $ 1,137 $ 7,552 $ 1,859 $ 10,908 $ 2,049 $ 195 $ 1,146 $ 243 $ 25,089 Loans: Ending balance $ 14,159 $ 650,542 $ 127,259 $ 736,603 $ 264,744 $ 11,218 $ 229,274 $ — $ 2,033,799 Loans deemed to be impaired $ — $ 365 $ — $ 2,603 $ 4,343 $ — $ — $ — $ 7,311 Loans not deemed to be impaired $ 14,159 $ 650,177 $ 127,259 $ 734,000 $ 260,401 $ 11,218 $ 229,274 $ — $ 2,026,488 During the six months ending June 30, 2017, the Company’s provision was primarily attributable to an increase in commercial and industrial and residential real estate balances offset, somewhat, by changes in historical loss and qualitative factors. During the three months ending June 30, 2017 the Company’s provision was primarily attributable to an increase in residential real estate loan balances offset, somewhat, by changes in historical loss and qualitative factors. There was also an increase in commercial and industrial originations, which increased the commercial and industrial allocation and lower historical loss rate, which decreased the consumer allocations. Further information pertaining to the allowance for loan losses for the three months ending June 30, 2016 follows: Construction Commercial Municipal Commercial Residential Consumer Home Unallocated Total (in thousands) Allowance for loan losses: Balance at March 31, 2016 $ 1,973 $ 6,693 $ 990 $ 10,533 $ 1,249 $ 693 $ 1,185 $ 228 $ 23,544 Charge-offs — — — — — (111 ) — — (111 ) Recoveries — 56 — — 2 106 — — 164 Provision 264 (878 ) 811 128 53 (77 ) 9 40 350 Reclassification to other liabilities (3 ) (29 ) — (11 ) (2 ) (3 ) (36 ) — (84 ) Ending balance at June 30, 2016 $ 2,234 $ 5,842 $ 1,801 $ 10,650 $ 1,302 $ 608 $ 1,158 $ 268 $ 23,863 Amount of allowance for loan losses for loans deemed to be impaired $ 6 $ 10 $ — $ 151 $ 7 $ — $ — $ — $ 174 Amount of allowance for loan losses for loans not deemed to be impaired $ 2,228 $ 5,832 $ 1,801 $ 10,499 $ 1,295 $ 608 $ 1,158 $ 268 $ 23,689 Loans: Ending balance $ 31,178 $ 493,033 $ 134,386 $ 728,658 $ 219,494 $ 11,339 $ 183,816 $ — $ 1,801,904 Loans deemed to be impaired $ 96 $ 410 $ — $ 3,736 $ 215 $ — $ — $ — $ 4,457 Loans not deemed to be impaired $ 31,082 $ 492,623 $ 134,386 $ 724,922 $ 219,279 $ 11,339 $ 183,816 $ — $ 1,797,447 Further information pertaining to the allowance for loan losses for the six months ending June 30, 2016 follows: Construction Commercial Municipal Commercial Residential Consumer Home Unallocated Total (in thousands) Allowance for loan losses: Balance at December 31, 2015 $ 2,041 $ 5,899 $ 994 $ 10,589 $ 1,320 $ 644 $ 1,077 $ 511 $ 23,075 Charge-offs — — — — — (180 ) — — (180 ) Recoveries — 91 — — 3 158 — — 252 Provision 196 (119 ) 807 72 (19 ) (11 ) 117 (243 ) 800 Reclassification to other liabilities (3 ) (29 ) — (11 ) (2 ) (3 ) (36 ) — (84 ) Ending balance at June 30, 2016 $ 2,234 $ 5,842 $ 1,801 $ 10,650 $ 1,302 $ 608 $ 1,158 $ 268 $ 23,863 Amount of allowance for loan losses for loans deemed to be impaired $ 6 $ 10 $ — $ 151 $ 7 $ — $ — $ — $ 174 Amount of allowance for loan losses for loans not deemed to be impaired $ 2,228 $ 5,832 $ 1,801 $ 10,499 $ 1,295 $ 608 $ 1,158 $ 268 $ 23,689 Loans: Ending balance $ 31,178 $ 493,033 $ 134,386 $ 728,658 $ 219,494 $ 11,339 $ 183,816 $ — $ 1,801,904 Loans deemed to be impaired $ 96 $ 410 $ — $ 3,736 $ 215 $ — $ — $ — $ 4,457 Loans not deemed to be impaired $ 31,082 $ 492,623 $ 134,386 $ 724,922 $ 219,279 $ 11,339 $ 183,816 $ — $ 1,797,447 During the six months ending June 30, 2016, the Company’s provision was primarily attributable to an increase in municipal balances. During the three months ending June 30, 2016 the Company’s provision was primarily attributable to an increase in construction loan balances. There was also an increase in municipal originations, which increased the municipal allocation and commercial and industrial loan payoffs, which decreased the commercial and industrial allocations. The Company utilizes a six grade internal loan rating system for commercial real estate, construction and commercial loans as follows: Loans rated 1-3 Loans in this category are considered “pass” rated loans with low to average risk. Loans rated 4 (Monitor): These loans represent classified loans that management is closely monitoring for credit quality. These loans have had or may have minor credit quality deterioration as of June 30, 2017 and December 31, 2016. Loans rated 5 (Substandard): Substandard loans represent classified loans that management is closely monitoring for credit quality. These loans have had more significant credit quality deterioration as of June 30, 2017 and December 31, 2016. Loans rated 6 (Doubtful): Doubtful loans represent classified loans that management is closely monitoring for credit quality. These loans had more significant credit quality deterioration as of June 30, 2017 and December 31, 2016 and are doubtful for full collection. Impaired: Impaired loans represent classified loans that management is closely monitoring for credit quality. A loan is classified as impaired when it is probable that the Company will be unable to collect all amounts due. The following table presents the Company’s loans by risk rating at June 30, 2017. Construction Commercial Municipal Commercial (in thousands) Grade: 1-3 $ 14,159 $ 650,177 $ 127,259 $ 704,531 4 (Monitor) — — — 29,469 5 (Substandard) — — — — 6 (Doubtful) — — — — Impaired — 365 — 2,603 Total $ 14,159 $ 650,542 $ 127,259 $ 736,603 The following table presents the Company’s loans by risk rating at December 31, 2016. Construction Commercial Municipal Commercial (in thousands) Grade: 1-3 $ 14,834 $ 612,114 $ 135,418 $ 661,271 4 (Monitor) — — — 31,753 5 (Substandard) — — — — 6 (Doubtful) — — — — Impaired 94 389 — 3,149 Total $ 14,928 $ 612,503 $ 135,418 $ 696,173 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 June 30, 2017 and are included within the total loan portfolio. Commercial Municipal Commercial Total (in thousands) Credit Rating: Aaa – Aa3 $ 341,777 $ 66,484 $ 45,615 $ 453,876 A1 – A3 218,222 8,225 128,927 355,374 Baa1 – Baa3 — 46,970 125,775 172,745 Ba2 — 2,730 — 2,730 Total $ 559,999 $ 124,409 $ 300,317 $ 984,725 Credit ratings issued by national organizations were utilized as credit quality indicators as presented in the following table at December 31, 2016. Commercial Municipal Commercial Total (in thousands) Credit Rating: Aaa – Aa3 $ 334,674 $ 66,245 $ 6,596 $ 407,515 A1 – A3 188,777 33,365 129,423 351,565 Baa1 – Baa3 — 26,970 127,366 154,336 Ba2 — 3,610 — 3,610 Total $ 523,451 $ 130,190 $ 263,385 $ 917,026 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 June 30, 2017 follows: Accruing 30-89 Days Non Accruing Total Current Total (in thousands) Construction and land development $ — $ — $ — $ — $ 14,159 $ 14,159 Commercial and industrial 404 49 — 453 650,089 650,542 Municipal — — — — 127,259 127,259 Commercial real estate 455 230 — 685 735,918 736,603 Residential real estate 984 735 — 1,719 263,025 264,744 Consumer and overdrafts 6 1 — 7 11,211 11,218 Home equity 1,357 107 — 1,464 227,810 229,274 Total $ 3,206 $ 1,122 $ — $ 4,328 $ 2,029,471 $ 2,033,799 Further information pertaining to the allowance for loan losses at December 31, 2016 follows: Accruing 30-89 Days Non Accruing Total Current Total (in thousands) Construction and land development $ — $ 94 $ — $ 94 $ 14,834 $ 14,928 Commercial and industrial 37 65 — 102 612,401 612,503 Municipal — — — — 135,418 135,418 Commercial real estate 597 150 — 747 695,426 696,173 Residential real estate 245 656 — 901 240,456 241,357 Consumer and overdrafts — 11 — 11 11,686 11,697 Home equity 735 108 — 843 211,014 211,857 Total $ 1,614 $ 1,084 $ — $ 2,698 $ 1,921,235 $ 1,923,933 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 charged-off The following is information pertaining to impaired loans for June 30, 2017: Carrying Unpaid Required Average Interest Average Interest (in thousands) With no required reserve recorded: Construction and land development $ — $ — $ — $ — $ — $ — $ — Commercial and industrial 49 248 — 43 — 43 — Municipal — — — — — — — Commercial real estate — — — 294 — 421 — Residential real estate 79 169 — 81 2 84 3 Consumer — — — — — — — Home equity — — — — — — — Total $ 128 $ 417 $ — $ 418 $ 2 $ 548 $ 3 With required reserve recorded: Construction and land development $ — $ — $ — $ 69 $ — $ 80 $ — Commercial and industrial 316 331 11 326 4 332 8 Municipal — — — — — — — Commercial real estate 2,603 2,728 120 2,546 24 2,548 48 Residential real estate 4,264 4,265 69 1,145 24 701 25 Consumer — — — — — — — Home equity — — — — — — — Total $ 7,183 $ 7,324 $ 200 $ 4,086 $ 52 $ 3,661 $ 81 Total: Construction and land development $ — $ — $ — $ 69 $ — $ 80 $ — Commercial and industrial 365 579 11 369 4 375 8 Municipal — — — — — — — Commercial real estate 2,603 2,728 120 2,840 24 2,969 48 Residential real estate 4,343 4,434 69 1,226 26 785 28 Consumer — — — — — — — Home equity — — — — — — — Total $ 7,311 $ 7,741 $ 200 $ 4,504 $ 54 $ 4,209 $ 84 The following is information pertaining to impaired loans for June 30, 2016: Carrying Unpaid Required Average Interest Average Interest (in thousands) With no required reserve recorded: Construction and land development $ — $ — $ — $ — $ — $ — $ — Commercial and industrial 52 239 — 54 — 56 — Municipal — — — — — — — Commercial real estate 596 596 — 329 16 188 22 Residential real estate 103 190 — 106 2 108 4 Consumer — — — — — — — Home equity — — — — — — — Total $ 751 $ 1,025 $ — $ 489 $ 18 $ 352 $ 26 With required reserve recorded: Construction and land development $ 96 $ 108 $ 6 $ 97 $ — $ 97 $ — Commercial and industrial 358 373 10 370 5 374 9 Municipal — — — — — — — Commercial real estate 3,140 3,239 151 2,030 20 1,878 33 Residential real estate 112 112 7 283 1 505 3 Consumer — — — — — — — Home equity — — — 22 — 51 — Total $ 3,706 $ 3,832 $ 174 $ 2,802 $ 26 $ 2,905 $ 45 Total: Construction and land development $ 96 $ 108 $ 6 $ 97 $ — $ 97 $ — Commercial and industrial 410 612 10 424 5 430 9 Municipal — — — — — — — Commercial real estate 3,736 3,835 151 2,359 36 2,066 55 Residential real estate 215 302 7 389 3 613 7 Consumer — — — — — — — Home equity — — — 22 — 51 — Total $ 4,457 $ 4,857 $ 174 $ 3,291 $ 44 $ 3,257 $ 71 There were no troubled debt restructurings that occurred during the six-month There was one commercial real estate troubled debt restructuring during the six month period ending June 30, 2016. The pre-modification

Reclassifications Out of Accumu

Reclassifications Out of Accumulated Other Comprehensive Income	6 Months Ended
	Jun. 30, 2017
Text Block [Abstract]
Reclassifications Out of Accumulated Other Comprehensive Income	Note 5. Reclassifications Out of Accumulated Other Comprehensive Income Amount Reclassified from Accumulated Other Comprehensive Income Details about Accumulated Other Comprehensive Income Components Three Three Affected Line Item in the Statement where Net Income is Presented (in thousands) Unrealized gains and losses on available-for-sale $ — $ 45 Net gains on sales of investments — (18 ) Provision for income taxes $ — $ 27 Net income Accretion of unrealized losses transferred $ (662 ) $ (1,170 ) Interest on securities held-to-maturity 402 408 Provision for income taxes $ (260 ) $ (762 ) Net income Amortization of defined benefit pension items Prior-service costs $ (3 ) $ (3 )(b) Salaries and employee benefits Actuarial gains (losses) (385 ) (401 )(b) Salaries and employee benefits Total before tax (388 ) (404 ) Income before taxes 155 161 Provision for income taxes $ (233 ) $ (243 ) Net income Details about Accumulated Other Comprehensive Income Components Six Six Affected Line Item in the Statement where Net Income is Presented (in thousands) Unrealized gains and losses on available-for-sale $ — $ 45 Net gains on sales of investments — (18 ) Provision for income taxes $ — $ 27 Net income Accretion of unrealized losses transferred $ (1,324 ) $ (2,682 ) Interest on securities held-to-maturity 691 935 Provision for income taxes $ (633 ) $ (1,747 ) Net income Amortization of defined benefit pension items Prior-service costs $ (6 ) $ (5 )(b) Salaries and employee benefits Actuarial gains (losses) (770 ) (802 )(b) Salaries and employee benefits Total before tax (776 ) (807 ) Income before taxes 311 322 Provision for income taxes $ (465 ) $ (485 ) Net income (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")	6 Months Ended
	Jun. 30, 2017
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 June 30, 2017 and 2016. The following table is a reconciliation of basic EPS and diluted EPS. Three Months Ended Six Months Ended (in thousands except share and per share data) 2017 2016 2017 2016 Basic EPS Computation: Numerator: Net income, Class A $ 6,410 $ 4,902 $ 11,198 $ 9,071 Net income, Class B 1,747 1,339 3,055 2,478 Denominator: Weighted average shares outstanding, Class A 3,603,729 3,600,729 3,602,229 3,600,729 Weighted average shares outstanding, Class B 1,964,180 1,967,180 1,965,680 1,967,180 Basic EPS, Class A $ 1.78 $ 1.36 $ 3.11 $ 2.52 Basic EPS, Class B 0.89 0.68 1.55 1.26 Diluted EPS Computation: Numerator: Net income, Class A $ 6,410 $ 4,902 $ 11,198 $ 9,071 Net income, Class B 1,747 1,339 3,055 2,478 Total net income, for diluted EPS, Class A computation 8,157 6,241 14,253 11,549 Denominator: Weighted average shares outstanding, basic, Class A 3,603,729 3,600,729 3,602,229 3,600,729 Weighted average shares outstanding, Class B 1,964,180 1,967,180 1,965,680 1,967,180 Weighted average shares outstanding diluted, Class A 5,567,909 5,567,909 5,567,909 5,567,909 Weighted average shares outstanding, Class B 1,964,180 1,967,180 1,965,680 1,967,180 Diluted EPS, Class A $ 1.47 $ 1.12 $ 2.56 $ 2.07 Diluted EPS, Class B 0.89 0.68 1.55 1.26

Employee Benefits

Employee Benefits	6 Months Ended
	Jun. 30, 2017
Retirement Benefits [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. Components of Net Periodic Benefit Cost for the Three Months Ended June 30, Pension Benefits Supplemental Insurance/ 2017 2016 2017 2016 (in thousands) Service cost $ 310 $ 318 $ 395 $ 455 Interest 362 340 345 334 Expected return on plan assets (746 ) (694 ) — — Recognized prior service cost (benefit) (26 ) (26 ) 29 29 Recognized net actuarial losses 226 200 159 200 Net periodic benefit cost $ 126 $ 138 $ 928 $ 1,018 Components of Net Periodic Benefit Cost for the Six Months Ended June 30, Pension Benefits Supplemental Insurance/ 2017 2016 2017 2016 (in thousands) Service cost $ 620 $ 636 $ 790 $ 910 Interest 724 680 690 668 Expected return on plan assets (1,492 ) (1,388 ) — — Recognized prior service cost (benefit) (52 ) (52 ) 58 58 Recognized net actuarial losses 452 400 318 400 Net periodic benefit cost $ 252 $ 276 $ 1,856 $ 2,036 Contributions The Company intends to contribute $1,000,000 to the Pension Plan in 2017. As of June 30, 2017, $500,000 has been contributed.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 8. Fair Value Measurements The Company follows FASB ASC 820-10, Fair Value Measurements and Disclosures 820-10 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 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 non-investment The results of the fair value hierarchy as of June 30, 2017, 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 $ 1,995 $ — $ 1,995 $ — U.S . Government Sponsored Enterprises 10,000 — 10,000 — SBA Backed Securities 71,189 — 71,189 — U.S . Government Agency and Sponsored Mortgage-Backed Securities 223,782 — 223,782 — Privately Issued Residential Mortgage-Backed Securities 1,015 — 1,015 — Obligations Issued by States and Political Subdivisions 98,049 — — 98,049 Other Debt Securities 4,992 — 4,992 — Equity Securities 318 318 — — Total $ 411,340 $ 318 $ 312,973 $ 98,049 Financial Instruments Measured at Fair Value on a Non-recurring Impaired Loans $ 230 $ — $ — $ 230 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 observable. 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 and six month periods ended June 30, 2017 amounted to $4,000 and ($5,000), respectively. There were no transfers between level 1, 2 and 3 for the six months ended June 30, 2017. There were no liabilities measured at fair value on a recurring or nonrecurring basis during the six month period ended June 30, 2017. 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) $ 98,049 Discounted cash flow Discount rate 0% -1% Impaired Loans $ 230 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. There was one auction rate security whose fair value is based on the evaluation of the underlying issuer, prevailing interest rates and market liquidity. The changes in Level 3 securities for the three month period ended June 30, 2017 are shown in the table below: Auction Rate Obligations Equity Total (in thousands) Balance at December 31, 2016 $ 4,298 $ 160,578 $ — $ 164,876 Purchases — 47,430 — 47,430 Maturities and calls — (114,144 ) — (114,144 ) Amortization — (113 ) — (113 ) Balance at June 30, 2017 $ 4,298 $ 93,751 $ — $ 98,049 The amortized cost of Level 3 securities was $98,457,000 at June 30, 2017 with an unrealized loss of $408,000. The securities in this category are generally municipal securities with no readily determinable fair value or failed auction rate securities. Management evaluated the fair value of these securities based on an evaluation of the underlying issuer, prevailing rates and market liquidity. The changes in Level 3 securities for the six month period ended June 30, 2016, are shown in the table below: Auction Rate Obligations Equity Total (in thousands) Balance at December 31, 2015 $ 3,820 $ 153,140 $ 37 $ 156,997 Purchases — 155,742 — 155,742 Maturities and calls — (100,245 ) (37 ) (100,282 ) Amortization — (97 ) — (97 ) Changes in fair value 478 — — 478 Balance at June 30, 2016 $ 4,298 $ 208,540 $ — $ 212,838 The amortized cost of Level 3 securities was $213,241,000 at June 30, 2016 with an unrealized loss of $403,000. 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, 2016, 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 $ 2,000 $ — $ 2,000 $ — U.S. Government Sponsored Enterprises 24,952 — 24,952 — SBA Backed Securities 57,767 — 57,767 — U.S. Government Agency and Sponsored Mortgage-Backed Securities 243,325 — 243,325 — Privately Issued Residential Mortgage-Backed Securities 1,109 — 1,109 — Obligations Issued by States and Political Subdivisions 164,876 — — 164,876 Other Debt Securities 4,924 — 4,924 — Equity Securities 344 344 — — Total $ 499,297 $ 344 $ 334,077 $ 164,876 Financial Instruments Measured at Fair Value on a Non-recurring Impaired Loans $ 260 $ — $ — $ 260 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 2016 for the estimated credit loss amounted to ($135,000). There were no transfers between level 1, 2 and 3 for the year ended December 31, 2016. There were no liabilities measured at fair value on a recurring or nonrecurring basis during the year ended December 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) $ 164,876 Discounted cash flow Discount rate 0%-1% (3) Impaired Loans $ 260 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. There was one auction rate security whose fair value is based on the evaluation of the underlying issuer, prevailing interest rates and market liquidity.

Fair Values of Financial Instru

Fair Values of Financial Instruments	6 Months Ended
	Jun. 30, 2017
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: Loans Held-for-Sale: Loans: For variable-rate loans, that reprice frequently and with no significant change in credit risk, fair values are based on carrying amounts. The fair value of other loans is estimated using discounted cash flow analysis, based on interest rates currently being offered for loans with similar terms to borrowers of similar credit quality. Incremental credit risk for nonperforming loans has been considered. Time deposits: The fair value of time deposits was estimated using a discounted cash flow approach that applies prevailing market interest rates for similar maturity instruments. The fair values of the Company’s time deposit liabilities do not take into consideration the value of the Company’s long-term relationships with depositors, which may have significant value. Other borrowed funds: The fair value of other borrowed funds is based on the discounted value of contractual cash flows. The discount rate used is estimated based on the rates currently offered for other borrowed funds of similar remaining maturities. Subordinated debentures: The fair value of subordinated debentures is based on the discounted value of contractual cash flows. The discount rate used is estimated based on the rates currently offered for other subordinated debentures of similar remaining maturities. The following presents (in thousands) the carrying amount, estimated fair value, and placement in the fair value hierarchy of the Company’s financial instruments as of June 30, 2017 and December 31, 2016. 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 June 30, 2017 Carrying Estimated Fair Value Fair Value Fair Value (in thousands) Financial assets: Securities held-to-maturity $ 1,722,875 $ 1,706,840 $ — $ 1,706,840 $ — Loans (1) 2,008,510 1,987,896 — — 1,987,896 Financial liabilities: Time deposits 575,410 577,804 — 577,804 — Other borrowed funds 455,500 457,252 — 457,252 — Subordinated debentures 36,083 36,083 — — 36,083 December 31, 2016 Financial assets: Securities held-to-maturity $ 1,653,986 $ 1,635,808 $ — $ 1,635,808 $ — Loans (1) 1,899,527 1,873,703 — — 1,873,703 Financial liabilities: Time deposits 478,359 480,133 — 480,133 — Other borrowed funds 293,000 294,940 — 294,940 — 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	6 Months Ended
	Jun. 30, 2017
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Developments	Note 10. Recent Accounting Developments In March 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) ASU 2017-08, 310-20) In March 2017, the FASB issued ASU 2017-07, In February 2017, the FASB issued ASU 2017-06, In February 2017, the FASB issued ASU 2017-05, 610-20). 610-20, In January 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2017-04, In June 2016, the FASB issued ASU 2016-13, In May 2016, the FASB issued ASU 2016-12, ASU 2015-14 2014-09 ASU 2016-12 In February 2016, the FASB issued ASU 2016-02,

Recent Accounting Developments

Recent Accounting Developments (Policies)	6 Months Ended
	Jun. 30, 2017
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Developments	Recent Accounting Developments In March 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) ASU 2017-08, 310-20) In March 2017, the FASB issued ASU 2017-07, In February 2017, the FASB issued ASU 2017-06, In February 2017, the FASB issued ASU 2017-05, 610-20). 610-20, In January 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2017-04, In June 2016, the FASB issued ASU 2016-13, In May 2016, the FASB issued ASU 2016-12, ASU 2015-14 2014-09 ASU 2016-12 In February 2016, the FASB issued ASU 2016-02,

Securities Available-for-Sale (

Securities Available-for-Sale (Tables)	6 Months Ended
	Jun. 30, 2017
Text Block [Abstract]
Summary of Securities Available-for-Sale	June 30, 2017 December 31, 2016 Amortized Gross Gross Fair Value Amortized Gross Gross Fair (in thousands) U.S. Treasury $ 1,999 $ — $ 4 $ 1,995 $ 2,000 $ — $ — $ 2,000 U.S. Government Sponsored Enterprises 10,000 — — 10,000 25,000 — 48 24,952 SBA Backed Securities 71,357 27 195 71,189 57,899 14 146 57,767 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 223,655 463 336 223,782 243,703 293 671 243,325 Privately Issued Residential Mortgage-Backed Securities 1,025 3 13 1,015 1,121 2 14 1,109 Obligations Issued by States and Political Subdivisions 98,457 — 408 98,049 165,281 — 405 164,876 Other Debt Securities 5,100 85 193 4,992 5,100 18 194 4,924 Equity Securities 116 202 — 318 116 228 — 344 Total $ 411,709 $ 780 $ 1,149 $ 411,340 $ 500,220 $ 555 $ 1,478 $ 499,297
Maturity Distribution of Securities Available-for-Sale	The following table shows the maturity distribution of the Company’s securities available-for-sale Amortized Fair Value (in thousands) Within one year $ 90,264 $ 90,255 After one but within five years 132,716 132,786 After five but within ten years 105,344 105,360 More than 10 years 81,769 81,270 Non-maturing 1,616 1,669 Total $ 411,709 $ 411,340
Continuous Unrealized Loss Position for Less than 12 Months and 12 Months or Longer	The following table shows the temporarily impaired securities of the Company’s available-for-sale June 30, 2017 Less than 12 months 12 months or longer Total Temporarily Impaired Investments Fair Unrealized Fair Unrealized Fair Value Unrealized (in thousands) U.S. Treasury $ 1,995 $ 4 $ — $ — $ 1,995 $ 4 U.S. Government Sponsored Enterprises — — — — — — SBA Backed Securities 27,850 116 17,775 79 45,625 195 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 36,251 83 66,121 253 102,372 336 Privately Issued Residential Mortgage-Backed Securities — — 707 13 707 13 Obligations Issued by States and Political Subdivisions — — 4,297 408 4,297 408 Other Debt Securities — — 1,907 193 1,907 193 Total temporarily impaired securities $ 66,096 $ 203 $ 90,807 $ 946 $ 156,903 $ 1,149 The following table shows the temporarily impaired securities of the Company’s available-for-sale Temporarily Impaired Investments December 31, 2016 Less than 12 months 12 months or longer Total Fair Value Unrealized Fair Unrealized Fair Value Unrealized (in thousands) U.S. Government Sponsored Enterprises $ 24,952 $ 48 $ — $ — $ 24,952 $ 48 SBA Backed Securities 52,346 145 951 1 53,297 146 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 135,612 485 31,504 186 167,116 671 Privately Issued Residential Mortgage-Backed Securities — — 757 14 757 14 Obligations Issued by States and Political Subdivisions — — 4,298 405 4,298 405 Other Debt Securities 453 47 1,553 147 2,006 194 Total temporarily impaired securities $ 213,363 $ 725 $ 39,063 $ 753 $ 252,426 $ 1,478

Investment Securities Held-to21

Investment Securities Held-to-Maturity (Tables)	6 Months Ended
	Jun. 30, 2017
Text Block [Abstract]
Summary of Held-to-Maturity Securities	June 30, 2017 December 31, 2016 Amortized Gross Gross Estimated Amortized Gross Gross Estimated (in thousands) U.S. Government Sponsored Enterprises $ 134,378 $ 931 $ 287 $ 135,022 $ 148,326 $ 1,066 $ 527 $ 148,865 SBA Backed Securities 54,427 3 779 53,651 46,140 — 1,088 45,052 U.S. Government Agency and Sponsored Enterprises Mortgage-Backed Securities 1,534,070 5,419 21,322 1,518,167 1,459,520 4,948 22,577 1,441,891 Total $ 1,722,875 $ 6,353 $ 22,388 $ 1,706,840 $ 1,653,986 $ 6,014 $ 24,192 $ 1,635,808
Company's Securities Held-to-Maturity	The following table shows the maturity distribution of the Company’s securities held-to-maturity Amortized Fair Value (in thousands) Within one year $ 45,780 $ 45,827 After one but within five years 1,224,104 1,213,863 After five but within ten years 449,698 444,027 More than ten years 3,293 3,123 Total $ 1,722,875 $ 1,706,840
Unrealized Market Loss of Securities	The following table shows the temporarily impaired securities of the Company’s held-to-maturity June 30, 2017 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 $ 45,209 $ 287 $ — $ — $ 45,209 $ 287 SBA Backed Securities 50,633 779 — — 50,633 779 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 1,015,890 18,964 76,584 2,358 1,092,474 21,322 Total temporarily impaired securities $ 1,111,732 $ 20,030 $ 76,584 $ 2,358 $ 1,188,316 $ 22,388 The following table shows the temporarily impaired securities of the Company’s held-to-maturity December 31, 2016 Less Than 12 Months 12 Months or Longer Total Temporarily Impaired Investments Fair Unrealized Fair Unrealized Fair Unrealized (in thousands) U.S. Government Sponsored Enterprises $ 59,219 $ 527 $ — $ — $ 59,219 $ 527 SBA Backed Securities 45,052 1,088 — — 45,052 1,088 U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities 1,008,960 20,725 58,535 1,852 1,067,495 22,577 Total temporarily impaired securities $ 1,113,231 $ 22,340 $ 58,535 $ 1,852 $ 1,171,766 $ 24,192

Allowance for Loan Losses (Tabl

Allowance for Loan Losses (Tables)	6 Months Ended
	Jun. 30, 2017
Receivables [Abstract]
Summary of Changes in Allowance for Loan Losses	The following table summarizes the changes in the Company’s allowance for loan losses for the periods indicated. Three months ended Six months ended 2017 2016 2017 2016 (in thousands) Allowance for loan losses, beginning of period $ 24,827 $ 23,544 $ 24,406 $ 23,075 Adjustment — (84 ) — (84 ) Loans charged off (100 ) (111 ) (197 ) (180 ) Recoveries on loans previously charged-off 72 164 190 252 Net (charge-offs) / recoveries (28 ) 53 (7 ) 72 Provision charged to expense 490 350 890 800 Allowance for loan losses, end of period $ 25,289 $ 23,863 $ 25,289 $ 23,863
Summary of Allowance for Loan Losses	Further information pertaining to the allowance for loan losses for the three months ending June 30, 2017 follows: Construction Commercial Municipal Commercial Residential Consumer Home Unallocated Total (in thousands) Allowance for loan losses: Balance at March 31, 2017 $ 873 $ 7,369 $ 1,899 $ 11,216 $ 1,671 $ 452 $ 1,050 $ 297 $ 24,827 Charge-offs — (29 ) — — — (71 ) — — (100 ) Recoveries — 34 — — — 38 — — 72 Provision 264 189 (40 ) (188 ) 447 (224 ) 96 (54 ) 490 Ending balance at June 30, 2017 $ 1,137 $ 7,563 $ 1,859 $ 11,028 $ 2,118 $ 195 $ 1,146 $ 243 $ 25,289 Amount of allowance for loan losses for loans deemed to be impaired $ — $ 11 $ — $ 120 $ 69 $ — $ — $ — $ 200 Amount of allowance for loan losses for loans not deemed to be impaired $ 1,137 $ 7,552 $ 1,859 $ 10,908 $ 2,049 $ 195 $ 1,146 $ 243 $ 25,089 Loans: Ending balance $ 14,159 $ 650,542 $ 127,259 $ 736,603 $ 264,744 $ 11,218 $ 229,274 $ — $ 2,033,799 Loans deemed to be impaired $ — $ 365 $ — $ 2,603 $ 4,343 $ — $ — $ — $ 7,311 Loans not deemed to be impaired $ 14,159 $ 650,177 $ 127,259 $ 734,000 $ 260,401 $ 11,218 $ 229,274 $ — $ 2,026,488 Further information pertaining to the allowance for loan losses for the six months ending June 30, 2017 follows: Construction Commercial Municipal Commercial Residential Consumer Home Unallocated Total (in thousands) Allowance for loan losses: Balance at December 31, 2016 $ 1,012 $ 6,972 $ 1,612 $ 11,135 $ 1,698 $ 582 $ 1,102 $ 293 $ 24,406 Charge-offs — (29 ) — — — (168 ) — — (197 ) Recoveries — 54 — — 2 134 — — 190 Provision 125 566 247 (107 ) 418 (353 ) 44 (50 ) 890 Ending balance at June 30, 2017 $ 1,137 $ 7,563 $ 1,859 $ 11,028 $ 2,118 $ 195 $ 1,146 $ 243 $ 25,289 Amount of allowance for loan losses for loans deemed to be impaired $ — $ 11 $ — $ 120 $ 69 $ — $ — $ — $ 200 Amount of allowance for loan losses for loans not deemed to be impaired $ 1,137 $ 7,552 $ 1,859 $ 10,908 $ 2,049 $ 195 $ 1,146 $ 243 $ 25,089 Loans: Ending balance $ 14,159 $ 650,542 $ 127,259 $ 736,603 $ 264,744 $ 11,218 $ 229,274 $ — $ 2,033,799 Loans deemed to be impaired $ — $ 365 $ — $ 2,603 $ 4,343 $ — $ — $ — $ 7,311 Loans not deemed to be impaired $ 14,159 $ 650,177 $ 127,259 $ 734,000 $ 260,401 $ 11,218 $ 229,274 $ — $ 2,026,488 Further information pertaining to the allowance for loan losses for the three months ending June 30, 2016 follows: Construction Commercial Municipal Commercial Residential Consumer Home Unallocated Total (in thousands) Allowance for loan losses: Balance at March 31, 2016 $ 1,973 $ 6,693 $ 990 $ 10,533 $ 1,249 $ 693 $ 1,185 $ 228 $ 23,544 Charge-offs — — — — — (111 ) — — (111 ) Recoveries — 56 — — 2 106 — — 164 Provision 264 (878 ) 811 128 53 (77 ) 9 40 350 Reclassification to other liabilities (3 ) (29 ) — (11 ) (2 ) (3 ) (36 ) — (84 ) Ending balance at June 30, 2016 $ 2,234 $ 5,842 $ 1,801 $ 10,650 $ 1,302 $ 608 $ 1,158 $ 268 $ 23,863 Amount of allowance for loan losses for loans deemed to be impaired $ 6 $ 10 $ — $ 151 $ 7 $ — $ — $ — $ 174 Amount of allowance for loan losses for loans not deemed to be impaired $ 2,228 $ 5,832 $ 1,801 $ 10,499 $ 1,295 $ 608 $ 1,158 $ 268 $ 23,689 Loans: Ending balance $ 31,178 $ 493,033 $ 134,386 $ 728,658 $ 219,494 $ 11,339 $ 183,816 $ — $ 1,801,904 Loans deemed to be impaired $ 96 $ 410 $ — $ 3,736 $ 215 $ — $ — $ — $ 4,457 Loans not deemed to be impaired $ 31,082 $ 492,623 $ 134,386 $ 724,922 $ 219,279 $ 11,339 $ 183,816 $ — $ 1,797,447 Further information pertaining to the allowance for loan losses for the six months ending June 30, 2016 follows: Construction Commercial Municipal Commercial Residential Consumer Home Unallocated Total (in thousands) Allowance for loan losses: Balance at December 31, 2015 $ 2,041 $ 5,899 $ 994 $ 10,589 $ 1,320 $ 644 $ 1,077 $ 511 $ 23,075 Charge-offs — — — — — (180 ) — — (180 ) Recoveries — 91 — — 3 158 — — 252 Provision 196 (119 ) 807 72 (19 ) (11 ) 117 (243 ) 800 Reclassification to other liabilities (3 ) (29 ) — (11 ) (2 ) (3 ) (36 ) — (84 ) Ending balance at June 30, 2016 $ 2,234 $ 5,842 $ 1,801 $ 10,650 $ 1,302 $ 608 $ 1,158 $ 268 $ 23,863 Amount of allowance for loan losses for loans deemed to be impaired $ 6 $ 10 $ — $ 151 $ 7 $ — $ — $ — $ 174 Amount of allowance for loan losses for loans not deemed to be impaired $ 2,228 $ 5,832 $ 1,801 $ 10,499 $ 1,295 $ 608 $ 1,158 $ 268 $ 23,689 Loans: Ending balance $ 31,178 $ 493,033 $ 134,386 $ 728,658 $ 219,494 $ 11,339 $ 183,816 $ — $ 1,801,904 Loans deemed to be impaired $ 96 $ 410 $ — $ 3,736 $ 215 $ — $ — $ — $ 4,457 Loans not deemed to be impaired $ 31,082 $ 492,623 $ 134,386 $ 724,922 $ 219,279 $ 11,339 $ 183,816 $ — $ 1,797,447
Loans by Risk Rating	The following table presents the Company’s loans by risk rating at June 30, 2017. Construction Commercial Municipal Commercial (in thousands) Grade: 1-3 $ 14,159 $ 650,177 $ 127,259 $ 704,531 4 (Monitor) — — — 29,469 5 (Substandard) — — — — 6 (Doubtful) — — — — Impaired — 365 — 2,603 Total $ 14,159 $ 650,542 $ 127,259 $ 736,603 The following table presents the Company’s loans by risk rating at December 31, 2016. Construction Commercial Municipal Commercial (in thousands) Grade: 1-3 $ 14,834 $ 612,114 $ 135,418 $ 661,271 4 (Monitor) — — — 31,753 5 (Substandard) — — — — 6 (Doubtful) — — — — Impaired 94 389 — 3,149 Total $ 14,928 $ 612,503 $ 135,418 $ 696,173
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 June 30, 2017 and are included within the total loan portfolio. Commercial Municipal Commercial Total (in thousands) Credit Rating: Aaa – Aa3 $ 341,777 $ 66,484 $ 45,615 $ 453,876 A1 – A3 218,222 8,225 128,927 355,374 Baa1 – Baa3 — 46,970 125,775 172,745 Ba2 — 2,730 — 2,730 Total $ 559,999 $ 124,409 $ 300,317 $ 984,725 Credit ratings issued by national organizations were utilized as credit quality indicators as presented in the following table at December 31, 2016. Commercial Municipal Commercial Total (in thousands) Credit Rating: Aaa – Aa3 $ 334,674 $ 66,245 $ 6,596 $ 407,515 A1 – A3 188,777 33,365 129,423 351,565 Baa1 – Baa3 — 26,970 127,366 154,336 Ba2 — 3,610 — 3,610 Total $ 523,451 $ 130,190 $ 263,385 $ 917,026
Aging of Past Due Loan Losses	Further information pertaining to the allowance for loan losses at June 30, 2017 follows: Accruing 30-89 Days Non Accruing Total Current Total (in thousands) Construction and land development $ — $ — $ — $ — $ 14,159 $ 14,159 Commercial and industrial 404 49 — 453 650,089 650,542 Municipal — — — — 127,259 127,259 Commercial real estate 455 230 — 685 735,918 736,603 Residential real estate 984 735 — 1,719 263,025 264,744 Consumer and overdrafts 6 1 — 7 11,211 11,218 Home equity 1,357 107 — 1,464 227,810 229,274 Total $ 3,206 $ 1,122 $ — $ 4,328 $ 2,029,471 $ 2,033,799 Further information pertaining to the allowance for loan losses at December 31, 2016 follows: Accruing 30-89 Days Non Accruing Total Current Total (in thousands) Construction and land development $ — $ 94 $ — $ 94 $ 14,834 $ 14,928 Commercial and industrial 37 65 — 102 612,401 612,503 Municipal — — — — 135,418 135,418 Commercial real estate 597 150 — 747 695,426 696,173 Residential real estate 245 656 — 901 240,456 241,357 Consumer and overdrafts — 11 — 11 11,686 11,697 Home equity 735 108 — 843 211,014 211,857 Total $ 1,614 $ 1,084 $ — $ 2,698 $ 1,921,235 $ 1,923,933
Information Pertaining to Impaired Loans	The following is information pertaining to impaired loans for June 30, 2017: Carrying Unpaid Required Average Interest Average Interest (in thousands) With no required reserve recorded: Construction and land development $ — $ — $ — $ — $ — $ — $ — Commercial and industrial 49 248 — 43 — 43 — Municipal — — — — — — — Commercial real estate — — — 294 — 421 — Residential real estate 79 169 — 81 2 84 3 Consumer — — — — — — — Home equity — — — — — — — Total $ 128 $ 417 $ — $ 418 $ 2 $ 548 $ 3 With required reserve recorded: Construction and land development $ — $ — $ — $ 69 $ — $ 80 $ — Commercial and industrial 316 331 11 326 4 332 8 Municipal — — — — — — — Commercial real estate 2,603 2,728 120 2,546 24 2,548 48 Residential real estate 4,264 4,265 69 1,145 24 701 25 Consumer — — — — — — — Home equity — — — — — — — Total $ 7,183 $ 7,324 $ 200 $ 4,086 $ 52 $ 3,661 $ 81 Total: Construction and land development $ — $ — $ — $ 69 $ — $ 80 $ — Commercial and industrial 365 579 11 369 4 375 8 Municipal — — — — — — — Commercial real estate 2,603 2,728 120 2,840 24 2,969 48 Residential real estate 4,343 4,434 69 1,226 26 785 28 Consumer — — — — — — — Home equity — — — — — — — Total $ 7,311 $ 7,741 $ 200 $ 4,504 $ 54 $ 4,209 $ 84 The following is information pertaining to impaired loans for June 30, 2016: Carrying Unpaid Required Average Interest Average Interest (in thousands) With no required reserve recorded: Construction and land development $ — $ — $ — $ — $ — $ — $ — Commercial and industrial 52 239 — 54 — 56 — Municipal — — — — — — — Commercial real estate 596 596 — 329 16 188 22 Residential real estate 103 190 — 106 2 108 4 Consumer — — — — — — — Home equity — — — — — — — Total $ 751 $ 1,025 $ — $ 489 $ 18 $ 352 $ 26 With required reserve recorded: Construction and land development $ 96 $ 108 $ 6 $ 97 $ — $ 97 $ — Commercial and industrial 358 373 10 370 5 374 9 Municipal — — — — — — — Commercial real estate 3,140 3,239 151 2,030 20 1,878 33 Residential real estate 112 112 7 283 1 505 3 Consumer — — — — — — — Home equity — — — 22 — 51 — Total $ 3,706 $ 3,832 $ 174 $ 2,802 $ 26 $ 2,905 $ 45 Total: Construction and land development $ 96 $ 108 $ 6 $ 97 $ — $ 97 $ — Commercial and industrial 410 612 10 424 5 430 9 Municipal — — — — — — — Commercial real estate 3,736 3,835 151 2,359 36 2,066 55 Residential real estate 215 302 7 389 3 613 7 Consumer — — — — — — — Home equity — — — 22 — 51 — Total $ 4,457 $ 4,857 $ 174 $ 3,291 $ 44 $ 3,257 $ 71

Reclassifications Out of Accu23

Reclassifications Out of Accumulated Other Comprehensive Income (Tables)	6 Months Ended
	Jun. 30, 2017
Text Block [Abstract]
Reclassifications Out of Accumulated Other Comprehensive Income	Amount Reclassified from Accumulated Other Comprehensive Income Details about Accumulated Other Comprehensive Income Components Three Three Affected Line Item in the Statement where Net Income is Presented (in thousands) Unrealized gains and losses on available-for-sale $ — $ 45 Net gains on sales of investments — (18 ) Provision for income taxes $ — $ 27 Net income Accretion of unrealized losses transferred $ (662 ) $ (1,170 ) Interest on securities held-to-maturity 402 408 Provision for income taxes $ (260 ) $ (762 ) Net income Amortization of defined benefit pension items Prior-service costs $ (3 ) $ (3 )(b) Salaries and employee benefits Actuarial gains (losses) (385 ) (401 )(b) Salaries and employee benefits Total before tax (388 ) (404 ) Income before taxes 155 161 Provision for income taxes $ (233 ) $ (243 ) Net income Details about Accumulated Other Comprehensive Income Components Six Six Affected Line Item in the Statement where Net Income is Presented (in thousands) Unrealized gains and losses on available-for-sale $ — $ 45 Net gains on sales of investments — (18 ) Provision for income taxes $ — $ 27 Net income Accretion of unrealized losses transferred $ (1,324 ) $ (2,682 ) Interest on securities held-to-maturity 691 935 Provision for income taxes $ (633 ) $ (1,747 ) Net income Amortization of defined benefit pension items Prior-service costs $ (6 ) $ (5 )(b) Salaries and employee benefits Actuarial gains (losses) (770 ) (802 )(b) Salaries and employee benefits Total before tax (776 ) (807 ) Income before taxes 311 322 Provision for income taxes $ (465 ) $ (485 ) Net income (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)	6 Months Ended
	Jun. 30, 2017
Earnings Per Share [Abstract]
Reconciliation of Basic EPS and Diluted EPS	The following table is a reconciliation of basic EPS and diluted EPS. Three Months Ended Six Months Ended (in thousands except share and per share data) 2017 2016 2017 2016 Basic EPS Computation: Numerator: Net income, Class A $ 6,410 $ 4,902 $ 11,198 $ 9,071 Net income, Class B 1,747 1,339 3,055 2,478 Denominator: Weighted average shares outstanding, Class A 3,603,729 3,600,729 3,602,229 3,600,729 Weighted average shares outstanding, Class B 1,964,180 1,967,180 1,965,680 1,967,180 Basic EPS, Class A $ 1.78 $ 1.36 $ 3.11 $ 2.52 Basic EPS, Class B 0.89 0.68 1.55 1.26 Diluted EPS Computation: Numerator: Net income, Class A $ 6,410 $ 4,902 $ 11,198 $ 9,071 Net income, Class B 1,747 1,339 3,055 2,478 Total net income, for diluted EPS, Class A computation 8,157 6,241 14,253 11,549 Denominator: Weighted average shares outstanding, basic, Class A 3,603,729 3,600,729 3,602,229 3,600,729 Weighted average shares outstanding, Class B 1,964,180 1,967,180 1,965,680 1,967,180 Weighted average shares outstanding diluted, Class A 5,567,909 5,567,909 5,567,909 5,567,909 Weighted average shares outstanding, Class B 1,964,180 1,967,180 1,965,680 1,967,180 Diluted EPS, Class A $ 1.47 $ 1.12 $ 2.56 $ 2.07 Diluted EPS, Class B 0.89 0.68 1.55 1.26

Employee Benefits (Tables)

Employee Benefits (Tables)	6 Months Ended
	Jun. 30, 2017
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Cost (Credit)	Components of Net Periodic Benefit Cost for the Three Months Ended June 30, Pension Benefits Supplemental Insurance/ 2017 2016 2017 2016 (in thousands) Service cost $ 310 $ 318 $ 395 $ 455 Interest 362 340 345 334 Expected return on plan assets (746 ) (694 ) — — Recognized prior service cost (benefit) (26 ) (26 ) 29 29 Recognized net actuarial losses 226 200 159 200 Net periodic benefit cost $ 126 $ 138 $ 928 $ 1,018 Components of Net Periodic Benefit Cost for the Six Months Ended June 30, Pension Benefits Supplemental Insurance/ 2017 2016 2017 2016 (in thousands) Service cost $ 620 $ 636 $ 790 $ 910 Interest 724 680 690 668 Expected return on plan assets (1,492 ) (1,388 ) — — Recognized prior service cost (benefit) (52 ) (52 ) 58 58 Recognized net actuarial losses 452 400 318 400 Net periodic benefit cost $ 252 $ 276 $ 1,856 $ 2,036

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2017
Fair Value Disclosures [Abstract]
Financial Instruments Measured at Fair Value on a Recurring and Non-recurring Basis	The results of the fair value hierarchy as of June 30, 2017, 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 $ 1,995 $ — $ 1,995 $ — U.S . Government Sponsored Enterprises 10,000 — 10,000 — SBA Backed Securities 71,189 — 71,189 — U.S . Government Agency and Sponsored Mortgage-Backed Securities 223,782 — 223,782 — Privately Issued Residential Mortgage-Backed Securities 1,015 — 1,015 — Obligations Issued by States and Political Subdivisions 98,049 — — 98,049 Other Debt Securities 4,992 — 4,992 — Equity Securities 318 318 — — Total $ 411,340 $ 318 $ 312,973 $ 98,049 Financial Instruments Measured at Fair Value on a Non-recurring Impaired Loans $ 230 $ — $ — $ 230 The results of the fair value hierarchy as of December 31, 2016, 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 $ 2,000 $ — $ 2,000 $ — U.S. Government Sponsored Enterprises 24,952 — 24,952 — SBA Backed Securities 57,767 — 57,767 — U.S. Government Agency and Sponsored Mortgage-Backed Securities 243,325 — 243,325 — Privately Issued Residential Mortgage-Backed Securities 1,109 — 1,109 — Obligations Issued by States and Political Subdivisions 164,876 — — 164,876 Other Debt Securities 4,924 — 4,924 — Equity Securities 344 344 — — Total $ 499,297 $ 344 $ 334,077 $ 164,876 Financial Instruments Measured at Fair Value on a Non-recurring Impaired Loans $ 260 $ — $ — $ 260
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) $ 98,049 Discounted cash flow Discount rate 0% -1% Impaired Loans $ 230 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. There was one auction rate security whose fair value is based on the evaluation of the underlying issuer, prevailing interest rates and market liquidity. 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) $ 164,876 Discounted cash flow Discount rate 0%-1% (3) Impaired Loans $ 260 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. There was one auction rate security whose fair value is based on the evaluation of the underlying issuer, prevailing interest rates and market liquidity.
Changes in Level 3 Securities	The changes in Level 3 securities for the three month period ended June 30, 2017 are shown in the table below: Auction Rate Obligations Equity Total (in thousands) Balance at December 31, 2016 $ 4,298 $ 160,578 $ — $ 164,876 Purchases — 47,430 — 47,430 Maturities and calls — (114,144 ) — (114,144 ) Amortization — (113 ) — (113 ) Balance at June 30, 2017 $ 4,298 $ 93,751 $ — $ 98,049 The changes in Level 3 securities for the six month period ended June 30, 2016, are shown in the table below: Auction Rate Obligations Equity Total (in thousands) Balance at December 31, 2015 $ 3,820 $ 153,140 $ 37 $ 156,997 Purchases — 155,742 — 155,742 Maturities and calls — (100,245 ) (37 ) (100,282 ) Amortization — (97 ) — (97 ) Changes in fair value 478 — — 478 Balance at June 30, 2016 $ 4,298 $ 208,540 $ — $ 212,838

Fair Values of Financial Inst27

Fair Values of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2017
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 June 30, 2017 and December 31, 2016. 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 June 30, 2017 Carrying Estimated Fair Value Fair Value Fair Value (in thousands) Financial assets: Securities held-to-maturity $ 1,722,875 $ 1,706,840 $ — $ 1,706,840 $ — Loans (1) 2,008,510 1,987,896 — — 1,987,896 Financial liabilities: Time deposits 575,410 577,804 — 577,804 — Other borrowed funds 455,500 457,252 — 457,252 — Subordinated debentures 36,083 36,083 — — 36,083 December 31, 2016 Financial assets: Securities held-to-maturity $ 1,653,986 $ 1,635,808 $ — $ 1,635,808 $ — Loans (1) 1,899,527 1,873,703 — — 1,873,703 Financial liabilities: Time deposits 478,359 480,133 — 480,133 — Other borrowed funds 293,000 294,940 — 294,940 — 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 28

Basis of Financial Statement Presentation - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2017Segment
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	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 411,709	$ 500,220
Gross Unrealized Gains	780	555
Gross Unrealized Losses	1,149	1,478
Total, Fair Value	411,340	499,297
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,999	2,000
Gross Unrealized Losses	4
Total, Fair Value	1,995	2,000
U.S. Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	10,000	25,000
Gross Unrealized Losses		48
Total, Fair Value	10,000	24,952
SBA Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	71,357	57,899
Gross Unrealized Gains	27	14
Gross Unrealized Losses	195	146
Total, Fair Value	71,189	57,767
U.S. Government Agency and Sponsored Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	223,655	243,703
Gross Unrealized Gains	463	293
Gross Unrealized Losses	336	671
Total, Fair Value	223,782	243,325
Privately Issued Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,025	1,121
Gross Unrealized Gains	3	2
Gross Unrealized Losses	13	14
Total, Fair Value	1,015	1,109
Obligations Issued by States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	98,457	165,281
Gross Unrealized Losses	408	405
Total, Fair Value	98,049	164,876
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,100	5,100
Gross Unrealized Gains	85	18
Gross Unrealized Losses	193	194
Total, Fair Value	4,992	4,924
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	116	116
Gross Unrealized Gains	202	228
Total, Fair Value	$ 318	$ 344

Securities Available-for-Sale30

Securities Available-for-Sale - Additional Information (Detail)	3 Months Ended	6 Months Ended
	Jun. 30, 2016USD ($)	Jun. 30, 2017USD ($)Security	Jun. 30, 2016USD ($)	Dec. 31, 2016USD ($)Security
Schedule of Available-for-sale Securities [Line Items]
Securities at fair value pledged to secure public deposits and repurchase agreements		$ 1,268,349,000		$ 1,147,207,000
Securities available-for-sale are securities at fair value pledged for borrowing		49,416,000		$ 53,396,000
Proceeds from sales of securities available-for-sale		$ 0	$ 1,946,000
Gross gains on sales of securities	$ 45,000		45,000
Federal Home Loan Bank [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross gains on sales of securities			$ 33,000
Securities AFS [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted average remaining life of investment securities available-for-sale		5 years 4 months 24 days
Number of securities, temporarily impaired for less than 12 months | Security		13		49
Number of securities, temporarily impaired for 12 months or longer | Security		27		15
Number of securities, temporarily impaired, total | Security		269		270
U.S. Government Sponsored Enterprises [Member] | Securities AFS [Member]
Schedule of Available-for-sale Securities [Line Items]
Weighted average remaining life		$ 10,000,000
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		$ 173,235,000		$ 210,780,000

Securities Available-for-Sale31

Securities Available-for-Sale - Maturity Distribution of Securities Available-for-Sale (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Within one year, Amortized Cost	$ 90,264
After one but within five years, Amortized Cost	132,716
After five but within ten years, Amortized Cost	105,344
More than 10 years, Amortized Cost	81,769
Non-maturing, Amortized Cost	1,616
Amortized Cost	411,709	$ 500,220
Within one year, Fair Value	90,255
After one but within five years, Fair Value	132,786
After five but within ten years, Fair Value	105,360
More than 10 years, Fair Value	81,270
Non-maturing, Fair Value	1,669
Total, Fair Value	$ 411,340	$ 499,297

Securities Available-for-Sale32

Securities Available-for-Sale - Continuous Unrealized Loss Position for 12 Months or Less and 12 Months or Longer (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	$ 66,096	$ 213,363
Less Than 12 Months, Unrealized Losses	203	725
12 Months or Longer, Fair Value	90,807	39,063
12 Months or Longer, Unrealized Losses	946	753
Total, Fair Value	156,903	252,426
Total, Unrealized Losses	1,149	1,478
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	1,995
Less Than 12 Months, Unrealized Losses	4
Total, Fair Value	1,995
Total, Unrealized Losses	4
U.S. Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value		24,952
Less Than 12 Months, Unrealized Losses		48
Total, Fair Value		24,952
Total, Unrealized Losses		48
SBA Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	27,850	52,346
Less Than 12 Months, Unrealized Losses	116	145
12 Months or Longer, Fair Value	17,775	951
12 Months or Longer, Unrealized Losses	79	1
Total, Fair Value	45,625	53,297
Total, Unrealized Losses	195	146
U.S. Government Agency and Sponsored Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	36,251	135,612
Less Than 12 Months, Unrealized Losses	83	485
12 Months or Longer, Fair Value	66,121	31,504
12 Months or Longer, Unrealized Losses	253	186
Total, Fair Value	102,372	167,116
Total, Unrealized Losses	336	671
Privately Issued Residential Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
12 Months or Longer, Fair Value	707	757
12 Months or Longer, Unrealized Losses	13	14
Total, Fair Value	707	757
Total, Unrealized Losses	13	14
Obligations Issued by States and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
12 Months or Longer, Fair Value	4,297	4,298
12 Months or Longer, Unrealized Losses	408	405
Total, Fair Value	4,297	4,298
Total, Unrealized Losses	408	405
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value		453
Less Than 12 Months, Unrealized Losses		47
12 Months or Longer, Fair Value	1,907	1,553
12 Months or Longer, Unrealized Losses	193	147
Total, Fair Value	1,907	2,006
Total, Unrealized Losses	$ 193	$ 194

Investment Securities Held-to33

Investment Securities Held-to-Maturity - Summary of Held-to-Maturity Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 1,722,875	$ 1,653,986
Gross Unrealized Gains	6,353	6,014
Gross Unrealized Losses	22,388	24,192
Estimated Fair Value	1,706,840	1,635,808
U.S. Government Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	134,378	148,326
Gross Unrealized Gains	931	1,066
Gross Unrealized Losses	287	527
Estimated Fair Value	135,022	148,865
SBA Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	54,427	46,140
Gross Unrealized Gains	3
Gross Unrealized Losses	779	1,088
Estimated Fair Value	53,651	45,052
U.S. Government Agency and Sponsored Mortgage-Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,534,070	1,459,520
Gross Unrealized Gains	5,419	4,948
Gross Unrealized Losses	21,322	22,577
Estimated Fair Value	$ 1,518,167	$ 1,441,891

Investment Securities Held-to34

Investment Securities Held-to-Maturity - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2017USD ($)Security	Jun. 30, 2016USD ($)	Dec. 31, 2016USD ($)Security
Schedule of Held-to-maturity Securities [Line Items]
Securities at fair value pledged to secure public deposits and repurchase agreements	$ 1,268,349,000		$ 1,147,207,000
Proceeds from sales of securities held-to-maturity	0	$ 192,000
Realized gross gains from sales of securities held-to-maturity	$ 12,000
Held-to-Maturity Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Weighted average remaining life of investment securities held-to-maturity	4 years 4 months 24 days
Number of securities, temporarily impaired for less than 12 months | Security	190		194
Number of securities, temporarily impaired for 12 months or longer | Security	22		16
Number of securities, temporarily impaired, total | Security	393		375
Held-to-Maturity Securities [Member] | U.S. Government Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Weighted average remaining life	$ 35,496,000
Federal Home Loan Bank [Member]
Schedule of Held-to-maturity Securities [Line Items]
Securities pledged for borrowing at the Federal Home Loan Bank	$ 305,269,000		$ 424,353,000

Investment Securities Held-to35

Investment Securities Held-to-Maturity - Company's Securities Held-to-Maturity (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Within one year, Amortized Cost	$ 45,780
After one but within five years, Amortized Cost	1,224,104
After five but within ten years, Amortized Cost	449,698
More than ten years, Amortized Cost	3,293
Amortized Cost	1,722,875	$ 1,653,986
Within one year, Fair Value	45,827
After one but within five years, Fair Value	1,213,863
After five but within ten years, Fair Value	444,027
More than ten years, Fair Value	3,123
Estimated Fair Value	$ 1,706,840	$ 1,635,808

Investment Securities Held-to36

Investment Securities Held-to-Maturity - Unrealized Market Loss of Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule of Held-to-maturity Securities [Line Items]
Less Than 12 Months, Fair Value	$ 1,111,732	$ 1,113,231
Less Than 12 Months, Unrealized Losses	20,030	22,340
12 Months or Longer, Fair Value	76,584	58,535
12 Months or Longer, Unrealized Losses	2,358	1,852
Total, Fair Value	1,188,316	1,171,766
Total, Unrealized Losses	22,388	24,192
U.S. Government Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Less Than 12 Months, Fair Value	45,209	59,219
Less Than 12 Months, Unrealized Losses	287	527
Total, Fair Value	45,209	59,219
Total, Unrealized Losses	287	527
SBA Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Less Than 12 Months, Fair Value	50,633	45,052
Less Than 12 Months, Unrealized Losses	779	1,088
Total, Fair Value	50,633	45,052
Total, Unrealized Losses	779	1,088
U.S. Government Agency and Sponsored Mortgage-Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Less Than 12 Months, Fair Value	1,015,890	1,008,960
Less Than 12 Months, Unrealized Losses	18,964	20,725
12 Months or Longer, Fair Value	76,584	58,535
12 Months or Longer, Unrealized Losses	2,358	1,852
Total, Fair Value	1,092,474	1,067,495
Total, Unrealized Losses	$ 21,322	$ 22,577

Allowance for Loan Losses - Ana

Allowance for Loan Losses - Analysis of Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Receivables [Abstract]
Allowance for loan losses, beginning of period	$ 24,827	$ 23,544	$ 24,406	$ 23,075
Adjustment		(84)		(84)
Loans charged off	(100)	(111)	(197)	(180)
Recoveries on loans previously charged-off	72	164	190	252
Net (charge-offs) / recoveries	(28)	53	(7)	72
Provision charged to expense	490	350	890	800
Allowance for loan losses, end of period	$ 25,289	$ 23,863	$ 25,289	$ 23,863

Allowance for Loan Losses - Sum

Allowance for Loan Losses - Summary of Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Allowance for loan losses:
Allowance for loan losses, beginning of period	$ 24,827	$ 23,544	$ 24,406	$ 23,075
Charge-offs	(100)	(111)	(197)	(180)
Recoveries	72	164	190	252
Provision	490	350	890	800
Reclassification to other liabilities		(84)		(84)
Allowance for loan losses, end of period	25,289	23,863	25,289	23,863
Amount of allowance for loan losses for loans deemed to be impaired	200	174	200	174
Amount of allowance for loan losses for loans not deemed to be impaired	25,089	23,689	25,089	23,689
Loans:
Total loans, net	2,033,799	1,801,904	2,033,799	1,801,904	$ 1,923,933
Loans deemed to be impaired	7,311	4,457	7,311	4,457
Loans not deemed to be impaired	2,026,488	1,797,447	2,026,488	1,797,447
Construction and Land Development [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	873	1,973	1,012	2,041
Provision	264	264	125	196
Reclassification to other liabilities		(3)		(3)
Allowance for loan losses, end of period	1,137	2,234	1,137	2,234
Amount of allowance for loan losses for loans deemed to be impaired		6		6
Amount of allowance for loan losses for loans not deemed to be impaired	1,137	2,228	1,137	2,228
Loans:
Total loans, net	14,159	31,178	14,159	31,178	14,928
Loans deemed to be impaired		96		96
Loans not deemed to be impaired	14,159	31,082	14,159	31,082
Commercial and Industrial [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	7,369	6,693	6,972	5,899
Charge-offs	(29)		(29)
Recoveries	34	56	54	91
Provision	189	(878)	566	(119)
Reclassification to other liabilities		(29)		(29)
Allowance for loan losses, end of period	7,563	5,842	7,563	5,842
Amount of allowance for loan losses for loans deemed to be impaired	11	10	11	10
Amount of allowance for loan losses for loans not deemed to be impaired	7,552	5,832	7,552	5,832
Loans:
Total loans, net	650,542	493,033	650,542	493,033	612,503
Loans deemed to be impaired	365	410	365	410
Loans not deemed to be impaired	650,177	492,623	650,177	492,623
Municipal [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	1,899	990	1,612	994
Provision	(40)	811	247	807
Allowance for loan losses, end of period	1,859	1,801	1,859	1,801
Amount of allowance for loan losses for loans not deemed to be impaired	1,859	1,801	1,859	1,801
Loans:
Total loans, net	127,259	134,386	127,259	134,386	135,418
Loans not deemed to be impaired	127,259	134,386	127,259	134,386
Commercial Real Estate [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	11,216	10,533	11,135	10,589
Provision	(188)	128	(107)	72
Reclassification to other liabilities		(11)		(11)
Allowance for loan losses, end of period	11,028	10,650	11,028	10,650
Amount of allowance for loan losses for loans deemed to be impaired	120	151	120	151
Amount of allowance for loan losses for loans not deemed to be impaired	10,908	10,499	10,908	10,499
Loans:
Total loans, net	736,603	728,658	736,603	728,658	696,173
Loans deemed to be impaired	2,603	3,736	2,603	3,736
Loans not deemed to be impaired	734,000	724,922	734,000	724,922
Residential Real Estate [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	1,671	1,249	1,698	1,320
Recoveries		2	2	3
Provision	447	53	418	(19)
Reclassification to other liabilities		(2)		(2)
Allowance for loan losses, end of period	2,118	1,302	2,118	1,302
Amount of allowance for loan losses for loans deemed to be impaired	69	7	69	7
Amount of allowance for loan losses for loans not deemed to be impaired	2,049	1,295	2,049	1,295
Loans:
Total loans, net	264,744	219,494	264,744	219,494	241,357
Loans deemed to be impaired	4,343	215	4,343	215
Loans not deemed to be impaired	260,401	219,279	260,401	219,279
Consumer [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	452	693	582	644
Charge-offs	(71)	(111)	(168)	(180)
Recoveries	38	106	134	158
Provision	(224)	(77)	(353)	(11)
Reclassification to other liabilities		(3)		(3)
Allowance for loan losses, end of period	195	608	195	608
Amount of allowance for loan losses for loans not deemed to be impaired	195	608	195	608
Loans:
Total loans, net	11,218	11,339	11,218	11,339	11,697
Loans not deemed to be impaired	11,218	11,339	11,218	11,339
Home Equity [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	1,050	1,185	1,102	1,077
Provision	96	9	44	117
Reclassification to other liabilities		(36)		(36)
Allowance for loan losses, end of period	1,146	1,158	1,146	1,158
Amount of allowance for loan losses for loans not deemed to be impaired	1,146	1,158	1,146	1,158
Loans:
Total loans, net	229,274	183,816	229,274	183,816	$ 211,857
Loans not deemed to be impaired	229,274	183,816	229,274	183,816
Unallocated [Member]
Allowance for loan losses:
Allowance for loan losses, beginning of period	297	228	293	511
Provision	(54)	40	(50)	(243)
Allowance for loan losses, end of period	243	268	243	268
Amount of allowance for loan losses for loans not deemed to be impaired	$ 243	$ 268	$ 243	$ 268

Allowance for Loan Losses - Loa

Allowance for Loan Losses - Loans by Risk Rating (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Loans by risk rating
Financing Receivable, Net	$ 2,033,799	$ 1,923,933	$ 1,801,904
Construction and Land Development [Member]
Loans by risk rating
Financing Receivable, Net	14,159	14,928	31,178
Commercial and Industrial [Member]
Loans by risk rating
Financing Receivable, Net	650,542	612,503	493,033
Municipal [Member]
Loans by risk rating
Financing Receivable, Net	127,259	135,418	134,386
Commercial Real Estate [Member]
Loans by risk rating
Financing Receivable, Net	736,603	696,173	$ 728,658
1-3 (Pass) [Member] | Construction and Land Development [Member]
Loans by risk rating
Financing Receivable, Net	14,159	14,834
1-3 (Pass) [Member] | Commercial and Industrial [Member]
Loans by risk rating
Financing Receivable, Net	650,177	612,114
1-3 (Pass) [Member] | Municipal [Member]
Loans by risk rating
Financing Receivable, Net	127,259	135,418
1-3 (Pass) [Member] | Commercial Real Estate [Member]
Loans by risk rating
Financing Receivable, Net	704,531	661,271
4 (Monitor) [Member] | Commercial Real Estate [Member]
Loans by risk rating
Financing Receivable, Net	29,469	31,753
Impaired [Member] | Construction and Land Development [Member]
Loans by risk rating
Financing Receivable, Net		94
Impaired [Member] | Commercial and Industrial [Member]
Loans by risk rating
Financing Receivable, Net	365	389
Impaired [Member] | Commercial Real Estate [Member]
Loans by risk rating
Financing Receivable, Net	$ 2,603	$ 3,149

Allowance for Loan Losses - L40

Allowance for Loan Losses - Loans by Credit Rating (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	$ 984,725	$ 917,026
Aaa - Aa3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	453,876	407,515
A1 - A3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	355,374	351,565
Baa1 - Baa3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	172,745	154,336
Ba2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	2,730	3,610
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	559,999	523,451
Commercial and Industrial [Member] | Aaa - Aa3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	341,777	334,674
Commercial and Industrial [Member] | A1 - A3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	218,222	188,777
Municipal [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	124,409	130,190
Municipal [Member] | Aaa - Aa3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	66,484	66,245
Municipal [Member] | A1 - A3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	8,225	33,365
Municipal [Member] | Baa1 - Baa3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	46,970	26,970
Municipal [Member] | Ba2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	2,730	3,610
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	300,317	263,385
Commercial Real Estate [Member] | Aaa - Aa3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	45,615	6,596
Commercial Real Estate [Member] | A1 - A3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	128,927	129,423
Commercial Real Estate [Member] | Baa1 - Baa3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and leases receivable net of deferred income credit quality	$ 125,775	$ 127,366

Allowance for Loan Losses - Agi

Allowance for Loan Losses - Aging of Past Due Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
Accruing 30-89 Days Past Due	$ 3,206	$ 1,614
Non Accrual	1,122	1,084
Accruing Greater than 90 Days	0	0
Total Past Due	4,328	2,698
Current Loans	2,029,471	1,921,235
Total loans, net	2,033,799	1,923,933	$ 1,801,904
Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Non Accrual		94
Accruing Greater than 90 Days	0	0
Total Past Due		94
Current Loans	14,159	14,834
Total loans, net	14,159	14,928	31,178
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Accruing 30-89 Days Past Due	404	37
Non Accrual	49	65
Accruing Greater than 90 Days	0	0
Total Past Due	453	102
Current Loans	650,089	612,401
Total loans, net	650,542	612,503	493,033
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Accruing Greater than 90 Days	0	0
Current Loans	127,259	135,418
Total loans, net	127,259	135,418	134,386
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Accruing 30-89 Days Past Due	455	597
Non Accrual	230	150
Accruing Greater than 90 Days	0	0
Total Past Due	685	747
Current Loans	735,918	695,426
Total loans, net	736,603	696,173	728,658
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Accruing 30-89 Days Past Due	984	245
Non Accrual	735	656
Accruing Greater than 90 Days	0	0
Total Past Due	1,719	901
Current Loans	263,025	240,456
Total loans, net	264,744	241,357	219,494
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Accruing 30-89 Days Past Due	6
Non Accrual	1	11
Accruing Greater than 90 Days	0	0
Total Past Due	7	11
Current Loans	11,211	11,686
Total loans, net	11,218	11,697	11,339
Home Equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Accruing 30-89 Days Past Due	1,357	735
Non Accrual	107	108
Accruing Greater than 90 Days	0	0
Total Past Due	1,464	843
Current Loans	227,810	211,014
Total loans, net	$ 229,274	$ 211,857	$ 183,816

Allowance for Loan Losses - Inf

Allowance for Loan Losses - Information Pertaining to Impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Carrying Value	$ 128	$ 751	$ 128	$ 751
With no required reserve recorded, Unpaid Balance Principal	417	1,025	417	1,025
With no required reserve recorded, Required Reserve	0	0	0	0
With no required reserve recorded, Average Carrying Value Recognized	418	489	548	352
With no required reserve recorded, Interest Income	2	18	3	26
With required reserve recorded, Carrying Value	7,183	3,706	7,183	3,706
With required reserve recorded, Unpaid Balance Principal	7,324	3,832	7,324	3,832
With required reserve recorded, Required Reserve	200	174	200	174
With required reserve recorded, Average Carrying Value Recognized	4,086	2,802	3,661	2,905
With required reserve recorded, Interest Income	52	26	81	45
Carrying Value	7,311	4,457	7,311	4,457
Unpaid Balance Principal	7,741	4,857	7,741	4,857
With required reserve recorded, Required Reserve	200	174	200	174
Average Carrying Value Recognized	4,504	3,291	4,209	3,257
Interest Income	54	44	84	71
Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Required Reserve	0	0	0	0
With required reserve recorded, Carrying Value		96		96
With required reserve recorded, Unpaid Balance Principal		108		108
With required reserve recorded, Required Reserve		6		6
With required reserve recorded, Average Carrying Value Recognized	69	97	80	97
Carrying Value		96		96
Unpaid Balance Principal		108		108
With required reserve recorded, Required Reserve		6		6
Average Carrying Value Recognized	69	97	80	97
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Carrying Value	49	52	49	52
With no required reserve recorded, Unpaid Balance Principal	248	239	248	239
With no required reserve recorded, Required Reserve	0	0	0	0
With no required reserve recorded, Average Carrying Value Recognized	43	54	43	56
With required reserve recorded, Carrying Value	316	358	316	358
With required reserve recorded, Unpaid Balance Principal	331	373	331	373
With required reserve recorded, Required Reserve	11	10	11	10
With required reserve recorded, Average Carrying Value Recognized	326	370	332	374
With required reserve recorded, Interest Income	4	5	8	9
Carrying Value	365	410	365	410
Unpaid Balance Principal	579	612	579	612
With required reserve recorded, Required Reserve	11	10	11	10
Average Carrying Value Recognized	369	424	375	430
Interest Income	4	5	8	9
Municipal [Member] | Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Required Reserve	0	0	0	0
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Carrying Value		596		596
With no required reserve recorded, Unpaid Balance Principal		596		596
With no required reserve recorded, Required Reserve	0	0	0	0
With no required reserve recorded, Average Carrying Value Recognized	294	329	421	188
With no required reserve recorded, Interest Income		16		22
With required reserve recorded, Carrying Value	2,603	3,140	2,603	3,140
With required reserve recorded, Unpaid Balance Principal	2,728	3,239	2,728	3,239
With required reserve recorded, Required Reserve	120	151	120	151
With required reserve recorded, Average Carrying Value Recognized	2,546	2,030	2,548	1,878
With required reserve recorded, Interest Income	24	20	48	33
Carrying Value	2,603	3,736	2,603	3,736
Unpaid Balance Principal	2,728	3,835	2,728	3,835
With required reserve recorded, Required Reserve	120	151	120	151
Average Carrying Value Recognized	2,840	2,359	2,969	2,066
Interest Income	24	36	48	55
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Carrying Value	79	103	79	103
With no required reserve recorded, Unpaid Balance Principal	169	190	169	190
With no required reserve recorded, Required Reserve	0	0	0	0
With no required reserve recorded, Average Carrying Value Recognized	81	106	84	108
With no required reserve recorded, Interest Income	2	2	3	4
With required reserve recorded, Carrying Value	4,264	112	4,264	112
With required reserve recorded, Unpaid Balance Principal	4,265	112	4,265	112
With required reserve recorded, Required Reserve	69	7	69	7
With required reserve recorded, Average Carrying Value Recognized	1,145	283	701	505
With required reserve recorded, Interest Income	24	1	25	3
Carrying Value	4,343	215	4,343	215
Unpaid Balance Principal	4,434	302	4,434	302
With required reserve recorded, Required Reserve	69	7	69	7
Average Carrying Value Recognized	1,226	389	785	613
Interest Income	26	3	28	7
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Required Reserve	0	0	0	0
Home Equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
With no required reserve recorded, Required Reserve	$ 0	0	$ 0	0
With required reserve recorded, Average Carrying Value Recognized		22		51
Average Carrying Value Recognized		$ 22		$ 51

Allowances for Loan Losses - Ad

Allowances for Loan Losses - Additional Information (Detail) - Commercial Portfolio Segment [Member]	6 Months Ended
	Jun. 30, 2016USD ($)Contracts
Financing Receivable, Allowance for Credit Losses [Line Items]
Number of troubled debt restructurings | Contracts	1
Pre-modification outstanding recorded investment	$ 2,091,000
Post-modification outstanding recorded investment	2,091,000
Financing allowance reduction in principal payments	3,000
Financing allowance reduction in interest payments	$ 1,000

Reclassifications Out of Accu44

Reclassifications Out of Accumulated Other Comprehensive Income - Reclassifications Out of Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gains on sales of securities		$ 45		$ 45
Provision for income taxes	$ (552)	(20)	$ (696)	(84)
Net income	8,157	6,241	14,253	11,549
Salaries and employee benefits	(10,719)	(10,040)	(21,862)	(19,816)
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		45		45
Provision for income taxes		(18)		(18)
Net income		27		27
Reclassification Out of Accumulated Other Comprehensive Income [Member] | Accretion of Unrealized Losses Transferred [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net gains on sales of securities	(662)	(1,170)	(1,324)	(2,682)
Provision for income taxes	402	408	691	935
Net income	(260)	(762)	(633)	(1,747)
Reclassification Out of Accumulated Other Comprehensive Income [Member] | Prior-Service Costs [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Salaries and employee benefits	(3)	(3)	(6)	(5)
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	(385)	(401)	(770)	(802)
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	(388)	(404)	(776)	(807)
Provision for income taxes	155	161	311	322
Net income	$ (233)	$ (243)	$ (465)	$ (485)

Earnings per Share ("EPS") - Ad

Earnings per Share ("EPS") - Additional Information (Detail) - Class A Common Stock [Member] - shares	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
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		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 8,157	$ 6,241	$ 14,253	$ 11,549
Class A Common Stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 6,410	$ 4,902	$ 11,198	$ 9,071
Weighted average shares outstanding, basic	3,603,729	3,600,729	3,602,229	3,600,729
Basic earnings per share	$ 1.78	$ 1.36	$ 3.11	$ 2.52
Net income	$ 6,410	$ 4,902	$ 11,198	$ 9,071
Weighted average shares outstanding, diluted	5,567,909	5,567,909	5,567,909	5,567,909
Diluted earnings per share	$ 1.47	$ 1.12	$ 2.56	$ 2.07
Class B Common Stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income	$ 1,747	$ 1,339	$ 3,055	$ 2,478
Weighted average shares outstanding, basic	1,964,180	1,967,180	1,965,680	1,967,180
Basic earnings per share	$ 0.89	$ 0.68	$ 1.55	$ 1.26
Net income	$ 1,747	$ 1,339	$ 3,055	$ 2,478
Weighted average shares outstanding, diluted	1,964,180	1,967,180	1,965,680	1,967,180
Diluted earnings per share	$ 0.89	$ 0.68	$ 1.55	$ 1.26

Employee Benefits - Additional

Employee Benefits - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2017USD ($)
Retirement Benefits [Abstract]
Number of years service to participate in supplemental plan	1 year
Current fiscal year contribution to pension plan	$ 500,000
Employer expected contribution to Pension Plan in 2017	$ 1,000,000

Employee Benefits - Components

Employee Benefits - Components of Net Periodic Benefit Cost (Credit) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 310	$ 318	$ 620	$ 636
Interest	362	340	724	680
Expected return on plan assets	(746)	(694)	(1,492)	(1,388)
Recognized prior service cost (benefit)	(26)	(26)	(52)	(52)
Recognized net actuarial losses	226	200	452	400
Net periodic benefit cost	126	138	252	276
Supplemental Insurance/ Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	395	455	790	910
Interest	345	334	690	668
Recognized prior service cost (benefit)	29	29	58	58
Recognized net actuarial losses	159	200	318	400
Net periodic benefit cost	$ 928	$ 1,018	$ 1,856	$ 2,036

Fair Value Measurements - Finan

Fair Value Measurements - Financial Instruments Measured at Fair Value on a Recurring and Non-recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	$ 411,340	$ 499,297
Fair Value Measurements, Level 1 Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	318	344
Fair Value Measurements, Level 2 Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	312,973	334,077
Fair Value Measurements, Level 3 Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	98,049	164,876
Financial Instruments Measured at Fair Value on a Non-recurring Basis
Impaired Loans	230	260
U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	1,995	2,000
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	1,995	2,000
SBA Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	71,189	57,767
SBA Backed Securities [Member] | Fair Value Measurements, Level 2 Inputs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	71,189	57,767
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	223,782	243,325
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	223,782	243,325
Privately Issued Residential Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	1,015	1,109
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	1,015	1,109
Obligations Issued by States and Political Subdivisions [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	98,049	164,876
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	98,049	164,876
Other Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	4,992	4,924
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	4,992	4,924
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	318	344
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	318	344
U.S. Government Sponsored Enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	10,000	24,952
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	10,000	24,952
Carrying Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	411,340	499,297
Financial Instruments Measured at Fair Value on a Non-recurring Basis
Impaired Loans	230	260
Carrying Value [Member] | U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	1,995	2,000
Carrying Value [Member] | SBA Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	71,189	57,767
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	223,782	243,325
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	1,015	1,109
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	98,049	164,876
Carrying Value [Member] | Other Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	4,992	4,924
Carrying Value [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	318	344
Carrying Value [Member] | U.S. Government Sponsored Enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities AFS	$ 10,000	$ 24,952

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Specific adjustments to impaired loans recognized	$ 4,000	$ (5,000)	$ (135,000)
Transfers between level 1, 2 and 3		0	0
Liabilities measured at fair value on a recurring or nonrecurring basis	0	0	$ 0
Fair Value Measurements, Level 3 Inputs [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Amortized cost of Level 3 securities	98,457,000	98,457,000		$ 213,241,000
Unrealized loss	$ 408,000	$ 408,000		$ 403,000

Fair Value Measurements - Asset

Fair Value Measurements - Assets Measured at Fair Value (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Securities AFS [Member]
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Fair Value	$ 98,049	$ 164,876
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	$ 230	$ 260
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 - Ass52

Fair Value Measurements - Assets Measured at Fair Value (Parenthetical) (Detail)	6 Months Ended
	Jun. 30, 2017
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	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 164,876	$ 156,997
Purchases	47,430	155,742
Maturities and calls	(114,144)	(100,282)
Amortization	(113)	(97)
Changes in fair value		478
Ending Balance	98,049	212,838
Auction Rate Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	4,298	3,820
Changes in fair value		478
Ending Balance	4,298	4,298
Obligations Issued by States and Political Subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	160,578	153,140
Purchases	47,430	155,742
Maturities and calls	(114,144)	(100,245)
Amortization	(113)	(97)
Ending Balance	$ 93,751	208,540
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance		37
Maturities and calls		$ (37)

Fair Values of Financial Inst54

Fair Values of Financial Instruments - Carrying Amount and Fair Value of Company's Financial Instruments (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Financial assets:
Securities held-to-maturity	$ 1,722,875	$ 1,653,986
Loans	2,008,510	1,899,527
Financial liabilities:
Time deposits	575,410	478,359
Other borrowed funds	455,500	293,000
Subordinated debentures	36,083	36,083
Carrying Value [Member]
Financial assets:
Securities held-to-maturity	1,722,875	1,653,986
Loans	2,008,510	1,899,527
Financial liabilities:
Time deposits	575,410	478,359
Other borrowed funds	455,500	293,000
Subordinated debentures	36,083	36,083
Estimated Fair Value [Member]
Financial assets:
Securities held-to-maturity	1,706,840	1,635,808
Loans	1,987,896	1,873,703
Financial liabilities:
Time deposits	577,804	480,133
Other borrowed funds	457,252	294,940
Subordinated debentures	36,083	36,083
Fair Value Measurements, Level 2 Inputs [Member]
Financial assets:
Securities held-to-maturity	1,706,840	1,635,808
Financial liabilities:
Time deposits	577,804	480,133
Other borrowed funds	457,252	294,940
Fair Value Measurements, Level 3 Inputs [Member]
Financial assets:
Loans	1,987,896	1,873,703
Financial liabilities:
Subordinated debentures	$ 36,083	$ 36,083