Loans, Allowance for Loan Losses and Credit Quality (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Summary of changes in allowance for loan losses
Beginning Balance	$ 48,403	$ 46,637	$ 48,260	$ 46,255
Charge-offs	(2,825)	(2,172)	(13,538)	(8,243)
Recoveries	562	813	1,318	1,584
Provision	3,606	2,000	13,706	7,682
Ending Balance	49,746	47,278	49,746	47,278
Ending Balance: Individually Evaluated for Impairment	2,755	2,685	2,755	2,685
Ending Balance: Collectively Evaluated for Impairment	46,991	44,593	46,991	44,593
Commercial and Industrial [Member]
Summary of changes in allowance for loan losses
Beginning Balance	11,558	11,083	11,682	10,423
Charge-offs	(1,267)	(749)	(5,989)	(2,455)
Recoveries	122	77	435	348
Provision	1,555	1,191	5,840	3,286
Ending Balance	11,968	11,602	11,968	11,602
Ending Balance: Individually Evaluated for Impairment	281	558	281	558
Ending Balance: Collectively Evaluated for Impairment	11,687	11,044	11,687	11,044
Commercial Real Estate [Member]
Summary of changes in allowance for loan losses
Beginning Balance	21,376	22,995	23,514	21,939
Charge-offs	(621)	(242)	(3,358)	(1,386)
Recoveries	188	98	188	98
Provision	962	134	1,561	2,334
Ending Balance	21,905	22,985	21,905	22,985
Ending Balance: Individually Evaluated for Impairment	737	306	737	306
Ending Balance: Collectively Evaluated for Impairment	21,168	22,679	21,168	22,679
Commercial Construction [Member]
Summary of changes in allowance for loan losses
Beginning Balance	2,220	2,071	2,076	2,145
Charge-offs				(769)
Recoveries		425		500
Provision	359	(605)	503	15
Ending Balance	2,579	1,891	2,579	1,891
Ending Balance: Individually Evaluated for Impairment
Ending Balance: Collectively Evaluated for Impairment	2,579	1,891	2,579	1,891
Small Business [Member]
Summary of changes in allowance for loan losses
Beginning Balance	1,320	2,053	1,896	3,740
Charge-offs	(98)	(386)	(404)	(970)
Recoveries	21	18	119	72
Provision	128	312	(240)	(845)
Ending Balance	1,371	1,997	1,371	1,997
Ending Balance: Individually Evaluated for Impairment	201	299	201	299
Ending Balance: Collectively Evaluated for Impairment	1,170	1,698	1,170	1,698
Residential Real Estate [Member]
Summary of changes in allowance for loan losses
Beginning Balance	2,981	3,242	3,113	2,915
Charge-offs	(227)	(88)	(441)	(490)
Recoveries	79		79
Provision	101	27	183	756
Ending Balance	2,934	3,181	2,934	3,181
Ending Balance: Individually Evaluated for Impairment	1,326	1,258	1,326	1,258
Ending Balance: Collectively Evaluated for Impairment	1,608	1,923	1,608	1,923
Consumer Home Equity [Member]
Summary of changes in allowance for loan losses
Beginning Balance	7,854	3,713	4,597	3,369
Charge-offs	(365)	(333)	(2,506)	(912)
Recoveries	36	13	67	30
Provision	443	723	5,810	1,629
Ending Balance	7,968	4,116	7,968	4,116
Ending Balance: Individually Evaluated for Impairment	36	24	36	24
Ending Balance: Collectively Evaluated for Impairment	7,932	4,092	7,932	4,092
Consumer Other [Member]
Summary of changes in allowance for loan losses
Beginning Balance	1,094	1,480	1,382	1,724
Charge-offs	(247)	(374)	(840)	(1,261)
Recoveries	116	182	430	536
Provision	58	218	49	507
Ending Balance	1,021	1,506	1,021	1,506
Ending Balance: Individually Evaluated for Impairment	174	240	174	240
Ending Balance: Collectively Evaluated for Impairment	$ 847	$ 1,266	$ 847	$ 1,266