Loans, Allowance for Loan Losses and Credit Quality (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Summary of changes in allowance for loan losses
Beginning Balance	$ 51,906	$ 48,340	$ 51,834	$ 48,260
Charge-offs	(2,477)	(8,768)	(4,051)	(10,713)
Recoveries	447	331	793	756
Provision	3,100	8,500	4,400	10,100
Ending Balance	52,976	48,403	52,976	48,403
Ending Balance: Individually Evaluated for Impairment	3,152	2,280	3,152	2,280
Ending Balance: Collectively Evaluated for Impairment	49,824	46,123	49,824	46,123
Commercial and Industrial [Member]
Summary of changes in allowance for loan losses
Beginning Balance	13,443	11,454	13,461	11,682
Charge-offs	(1,302)	(4,707)	(1,725)	(4,722)
Recoveries	103	113	239	313
Provision	2,081	4,698	2,350	4,285
Ending Balance	14,325	11,558	14,325	11,558
Ending Balance: Individually Evaluated for Impairment	775	278	775	278
Ending Balance: Collectively Evaluated for Impairment	13,550	11,280	13,550	11,280
Commercial Real Estate [Member]
Summary of changes in allowance for loan losses
Beginning Balance	22,569	22,829	22,598	23,514
Charge-offs	(196)	(2,133)	(603)	(2,737)
Recoveries	8		8
Provision	648	680	1,026	599
Ending Balance	23,029	21,376	23,029	21,376
Ending Balance: Individually Evaluated for Impairment	410	445	410	445
Ending Balance: Collectively Evaluated for Impairment	22,619	20,931	22,619	20,931
Commercial Construction [Member]
Summary of changes in allowance for loan losses
Beginning Balance	3,139	2,233	2,811	2,076
Charge-offs
Recoveries
Provision	283	(13)	611	144
Ending Balance	3,422	2,220	3,422	2,220
Ending Balance: Individually Evaluated for Impairment	0	0	0	0
Ending Balance: Collectively Evaluated for Impairment	3,422	2,220	3,422	2,220
Small Business [Member]
Summary of changes in allowance for loan losses
Beginning Balance	1,244	1,459	1,524	1,896
Charge-offs	(276)	(136)	(421)	(306)
Recoveries	37	46	76	98
Provision	290	(49)	116	(368)
Ending Balance	1,295	1,320	1,295	1,320
Ending Balance: Individually Evaluated for Impairment	153	140	153	140
Ending Balance: Collectively Evaluated for Impairment	1,142	1,180	1,142	1,180
Residential Real Estate [Member]
Summary of changes in allowance for loan losses
Beginning Balance	3,048	3,072	2,930	3,113
Charge-offs	(186)	(105)	(247)	(214)
Recoveries	86		86
Provision	11	14	190	82
Ending Balance	2,959	2,981	2,959	2,981
Ending Balance: Individually Evaluated for Impairment	1,670	1,209	1,670	1,209
Ending Balance: Collectively Evaluated for Impairment	1,289	1,772	1,289	1,772
Consumer Home Equity [Member]
Summary of changes in allowance for loan losses
Beginning Balance	7,716	6,077	7,703	4,597
Charge-offs	(257)	(1,391)	(534)	(2,141)
Recoveries	30	18	51	31
Provision	(222)	3,150	47	5,367
Ending Balance	7,267	7,854	7,267	7,854
Ending Balance: Individually Evaluated for Impairment	52	30	52	30
Ending Balance: Collectively Evaluated for Impairment	7,215	7,824	7,215	7,824
Consumer Other [Member]
Summary of changes in allowance for loan losses
Beginning Balance	747	1,216	807	1,382
Charge-offs	(260)	(296)	(521)	(593)
Recoveries	183	154	333	314
Provision	9	20	60	(9)
Ending Balance	679	1,094	679	1,094
Ending Balance: Individually Evaluated for Impairment	92	178	92	178
Ending Balance: Collectively Evaluated for Impairment	$ 587	$ 916	$ 587	$ 916