Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Assets
Cash and due from banks	$ 58,975	$ 52,877
Federal funds sold and interest-bearing deposits in other banks	159,900	167,847
Total cash and cash equivalents	218,875	220,724
Short-term investments	3,241	3,233
Securities available-for-sale, amortized cost $526,762 and $404,977, respectively	526,132	404,623
Securities held-to-maturity, fair value $1,589,183 and $1,438,960, respectively	1,565,191	1,438,903
Federal Home Loan Bank of Boston stock, at cost	21,148	28,807
Loans, net:
Commercial and industrial	549,290	452,235
Municipal	145,063	85,685
Construction and land development	19,522	27,421
Commercial real estate	692,778	721,506
Residential real estate	222,881	255,346
Home equity	200,085	178,020
Consumer and other	11,474	11,323
Total loans, net	1,841,093	1,731,536
Less: allowance for loan losses	24,208	23,075
Net loans	1,816,885	1,708,461
Bank premises and equipment	23,334	24,106
Accrued interest receivable	7,597	8,002
Goodwill	2,714	2,714
Other assets	113,206	107,868
Total assets	4,298,323	3,947,441
Deposits:
Demand deposits	645,317	541,955
Savings and NOW deposits	1,293,995	1,070,585
Money market accounts	1,067,170	989,094
Time deposits	454,631	473,426
Total deposits	3,461,113	3,075,060
Securities sold under agreements to repurchase	214,320	197,850
Other borrowed funds	293,000	368,000
Subordinated debentures	36,083	36,083
Due to broker	2,252	405
Other liabilities	57,774	55,499
Total liabilities	4,064,542	3,732,897
Stockholders' Equity
Preferred stock-$1.00 par value; 100,000 shares authorized; no shares issued and outstanding
Additional paid-in capital	12,292	12,292
Retained earnings	237,616	221,232
Stockholders' equity before adjustment of accumulated other comprehensive income (loss)	255,476	239,092
Unrealized losses on securities available-for-sale, net of taxes	(394)	(246)
Unrealized losses on securities transferred to held-to-maturity, net of taxes	(4,622)	(6,896)
Pension liability, net of taxes	(16,679)	(17,406)
Total accumulated other comprehensive loss, net of taxes	(21,695)	(24,548)
Total stockholders' equity	233,781	214,544
Total liabilities and stockholders' equity	4,298,323	3,947,441
Class A Common Stock [Member]
Stockholders' Equity
Common stock value	3,601	3,601
Total stockholders' equity	3,601	3,601
Class B Common Stock [Member]
Stockholders' Equity
Common stock value	1,967	1,967
Total stockholders' equity	$ 1,967	$ 1,967