Consolidated Statement of Income (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
INTEREST INCOME
Loans, taxable	$ 36,772	$ 40,163	$ 43,113
Loans, non-taxable	11,324	8,271	5,086
Securities available-for-sale, taxable	22,782	18,958	20,439
Securities available-for-sale, non-taxable	211	391	698
Federal Home Loan Bank of Boston dividends	46
Securities held-to-maturity	5,816	7,158	8,093
Federal funds sold, interest-bearing deposits in other banks and short-term investments	1,114	1,642	2,171
Total interest income	78,065	76,583	79,600
INTEREST EXPENSE
Savings and NOW deposits	2,539	4,072	5,258
Money market accounts	2,706	3,942	6,100
Time deposits (Note 8)	9,356	7,914	9,438
Securities sold under agreements to repurchase	379	573	576
Other borrowed funds and subordinated debentures	7,786	8,316	10,351
Total interest expense	22,766	24,817	31,723
Net interest income	55,299	51,766	47,877
Provision for loan losses (Note 6)	4,550	5,575	6,625
Net interest income after provision for loan losses	50,749	46,191	41,252
OTHER OPERATING INCOME
Service charges on deposit accounts	7,885	7,876	8,003
Lockbox fees	2,770	2,911	2,814
Brokerage commissions	441	230	140
Net gains on sales of securities	1,940	1,851	2,734
Other income	3,204	3,131	2,779
Total other operating income	16,240	15,999	16,470
OPERATING EXPENSES
Salaries and employee benefits (Note 15)	29,630	28,398	26,919
Occupancy	4,411	4,037	4,104
Equipment	2,235	2,132	2,372
FDIC assessments	2,025	2,965	3,336
Other (Note 18)	10,441	9,840	9,648
Total operating expenses	48,742	47,372	46,379
Income before income taxes	18,247	14,818	11,343
Provision for income taxes (Note 14)	1,554	1,244	1,183
Net income	$ 16,693	$ 13,574	$ 10,160
SHARE DATA (Note 13)
Weighted average number of shares outstanding, basic	5,540,644	5,533,506	5,532,249
Weighted average number of shares outstanding, diluted	5,541,794	5,535,742	5,534,340
Net income per share, basic	$ 3.01	$ 2.45	$ 1.84
Net income per share, diluted	$ 3.01	$ 2.45	$ 1.84