Loans, Allowance for Loan Losses and Credit Quality (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Summary of changes in allowance for loan losses
Beginning Balance	$ 52,976	$ 48,403	$ 51,834	$ 48,260
Charge-offs	(2,370)	(2,825)	(6,421)	(13,538)
Recoveries	306	562	1,099	1,318
Provision for loan losses	2,650	3,606	7,050	13,706
Ending Balance	53,562	49,746	53,562	49,746
Ending Balance: Individually Evaluated for Impairment	5,281	2,755	5,281	2,755
Ending Balance: Collectively Evaluated for Impairment	48,281	46,991	48,281	46,991
Commercial and Industrial [Member]
Summary of changes in allowance for loan losses
Beginning Balance	14,325	11,558	13,461	11,682
Charge-offs	(866)	(1,267)	(2,591)	(5,989)
Recoveries	24	122	263	435
Provision for loan losses	1,531	1,555	3,881	5,840
Ending Balance	15,014	11,968	15,014	11,968
Ending Balance: Individually Evaluated for Impairment	1,174	281	1,174	281
Ending Balance: Collectively Evaluated for Impairment	13,840	11,687	13,840	11,687
Commercial Real Estate [Member]
Summary of changes in allowance for loan losses
Beginning Balance	23,029	21,376	22,598	23,514
Charge-offs	(209)	(621)	(812)	(3,358)
Recoveries	89	188	97	188
Provision for loan losses	2,069	962	3,095	1,561
Ending Balance	24,978	21,905	24,978	21,905
Ending Balance: Individually Evaluated for Impairment	2,150	737	2,150	737
Ending Balance: Collectively Evaluated for Impairment	22,828	21,168	22,828	21,168
Commercial Construction [Member]
Summary of changes in allowance for loan losses
Beginning Balance	3,422	2,220	2,811	2,076
Charge-offs	(308)		(308)
Recoveries
Provision for loan losses	387	359	998	503
Ending Balance	3,501	2,579	3,501	2,579
Ending Balance: Individually Evaluated for Impairment	0	0	0	0
Ending Balance: Collectively Evaluated for Impairment	3,501	2,579	3,501	2,579
Small Business [Member]
Summary of changes in allowance for loan losses
Beginning Balance	1,295	1,320	1,524	1,896
Charge-offs	(84)	(98)	(505)	(404)
Recoveries	47	21	123	119
Provision for loan losses	(43)	128	73	(240)
Ending Balance	1,215	1,371	1,215	1,371
Ending Balance: Individually Evaluated for Impairment	111	201	111	201
Ending Balance: Collectively Evaluated for Impairment	1,104	1,170	1,104	1,170
Residential Real Estate [Member]
Summary of changes in allowance for loan losses
Beginning Balance	2,959	2,981	2,930	3,113
Charge-offs	(210)	(227)	(457)	(441)
Recoveries	5	79	91	79
Provision for loan losses	141	101	331	183
Ending Balance	2,895	2,934	2,895	2,934
Ending Balance: Individually Evaluated for Impairment	1,651	1,326	1,651	1,326
Ending Balance: Collectively Evaluated for Impairment	1,244	1,608	1,244	1,608
Consumer Home Equity [Member]
Summary of changes in allowance for loan losses
Beginning Balance	7,267	7,854	7,703	4,597
Charge-offs	(420)	(365)	(954)	(2,506)
Recoveries	22	36	73	67
Provision for loan losses	(1,555)	443	(1,508)	5,810
Ending Balance	5,314	7,968	5,314	7,968
Ending Balance: Individually Evaluated for Impairment	112	36	112	36
Ending Balance: Collectively Evaluated for Impairment	5,202	7,932	5,202	7,932
Consumer Other [Member]
Summary of changes in allowance for loan losses
Beginning Balance	679	1,094	807	1,382
Charge-offs	(273)	(247)	(794)	(840)
Recoveries	119	116	452	430
Provision for loan losses	120	58	180	49
Ending Balance	645	1,021	645	1,021
Ending Balance: Individually Evaluated for Impairment	83	174	83	174
Ending Balance: Collectively Evaluated for Impairment	$ 562	$ 847	$ 562	$ 847