Loans, Allowance for Loan Losses and Credit Quality (Details 11) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Interest income recognized on impaired loans
Average Recorded Investment	$ 70,959	$ 54,558	$ 73,282	$ 55,332
Interest Income Recognized	1,088	808	3,097	2,416
WITH NO RELATED ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	34,584	23,933	35,539	24,454
Interest Income Recognized	582	432	1,611	1,283
WITH AN ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	36,375	30,625	37,743	30,878
Interest Income Recognized	506	376	1,486	1,133
Commercial and Industrial [Member] | WITH NO RELATED ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	8,181	2,236	8,584	2,527
Interest Income Recognized	107	46	323	143
Commercial and Industrial [Member] | WITH AN ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	1,077	756	1,487	926
Interest Income Recognized	23	12	74	41
Commercial Real Estate [Member] | WITH NO RELATED ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	18,625	19,391	19,033	19,600
Interest Income Recognized	329	345	1,005	1,020
Commercial Real Estate [Member] | WITH AN ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	17,444	13,247	18,103	13,304
Interest Income Recognized	255	183	790	569
Commercial Construction [Member] | WITH NO RELATED ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment		551		560
Interest Income Recognized		11		32
Commercial Construction [Member] | WITH AN ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment
Interest Income Recognized
Small Business [Member] | WITH NO RELATED ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	1,461	1,641	1,543	1,627
Interest Income Recognized	25	28	79	82
Small Business [Member] | WITH AN ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	1,176	1,401	1,171	1,505
Interest Income Recognized	16	21	49	67
Residential Real Estate [Member] | WITH NO RELATED ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	2,709	2	2,730	5
Interest Income Recognized	81		84
Residential Real Estate [Member] | WITH AN ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	13,592	12,721	13,720	12,744
Interest Income Recognized	168	132	434	378
Consumer - Home Equity [Member] | WITH NO RELATED ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	3,527	22	3,571	22
Interest Income Recognized	39		117	1
Consumer - Home Equity [Member] | WITH AN ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	803	457	815	480
Interest Income Recognized	14	8	41	22
Consumer - Other [Member] | WITH NO RELATED ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	81	90	78	113
Interest Income Recognized	1	2	3	5
Consumer - Other [Member] | WITH AN ALLOWANCE RECORDED: [Member]
Interest income recognized on impaired loans
Average Recorded Investment	2,283	2,043	2,447	1,919
Interest Income Recognized	$ 30	$ 20	$ 98	$ 56