Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
ASSETS:
Cash and due from banks (Note 2)	$ 53,646	$ 50,187
Federal funds sold and interest-bearing deposits in other banks	98,637	157,579
Total cash and cash equivalents	152,283	207,766
Short-term investments	17,367	18,351
Securities available-for-sale, amortized cost $1,414,595 in 2012 and $1,244,972 in 2011 (Notes 3, 9 and 11)	1,434,801	1,258,676
Securities held-to-maturity, fair value $281,924 in 2012 and $184,822 in 2011 (Notes 4 and 11)	275,507	179,368
Federal Home Loan Bank of Boston, stock at cost	15,146	15,531
Loans, net (Note 5)	1,111,788	984,492
Less: allowance for loan losses (Note 6)	19,197	16,574
Net loans	1,092,591	967,918
Bank premises and equipment (Note 7)	23,899	21,757
Accrued interest receivable	5,811	6,022
Prepaid FDIC assessments	2,773	4,335
Other assets (Notes 5, 8 and 15)	66,031	63,501
Total assets	3,086,209	2,743,225
LIABILITIES AND STOCKHOLDERS' EQUITY
Demand deposits	438,429	365,854
Savings and NOW deposits	933,316	708,988
Money market accounts	653,345	616,241
Time deposits (Note 10)	419,983	433,501
Total deposits	2,445,073	2,124,584
Securities sold under agreements to repurchase (Note 11)	191,390	143,320
Other borrowed funds (Note 12)	195,144	244,143
Subordinated debentures (Note 12)	36,083	36,083
Other liabilities	38,529	34,446
Total liabilities	2,906,219	2,582,576
Commitments and contingencies (Notes 7, 17 and 18)
Stockholders' Equity (Note 14):
Preferred Stock - $1.00 par value; 100,000 shares authorized; no shares issued and outstanding
Additional paid-in capital	11,891	11,587
Retained earnings	162,892	146,039
Total stockholder's equity	180,337	163,168
Unrealized gains on securities available-for-sale, net of taxes	12,330	8,319
Pension liability, net of taxes	(12,677)	(10,838)
Total accumulated other comprehensive loss, net of taxes (Notes 3 and 14)	(347)	(2,519)
Total stockholders' equity	179,990	160,649
Total liabilities and stockholders' equity	3,086,209	2,743,225
Class A Common Stock
Stockholders' Equity (Note 14):
Common stock value	3,568	3,548
Total stockholders' equity	3,568	3,548
Class B Common Stock
Stockholders' Equity (Note 14):
Common stock value	1,986	1,994
Total stockholders' equity	$ 1,986	$ 1,994