Loans, Allowance for Loan Losses and Credit Quality (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Summary of changes in allowance for loan losses
Beginning Balance	$ 51,834	$ 48,260
Charge-offs	(1,574)	(1,945)
Recoveries	346	425
Provision	1,300	1,600
Ending Balance	51,906	48,340
Ending Balance: Individually Evaluated for Impairment	3,023	3,852
Ending Balance: Collectively Evaluated for Impairment	48,883	44,488
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality	0
Commercial and Industrial [Member]
Summary of changes in allowance for loan losses
Beginning Balance	13,461	11,682
Charge-offs	(423)	(15)
Recoveries	136	200
Provision	269	(413)
Ending Balance	13,443	11,454
Ending Balance: Individually Evaluated for Impairment	771	464
Ending Balance: Collectively Evaluated for Impairment	12,672	10,990
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality	0
Commercial Real Estate [Member]
Summary of changes in allowance for loan losses
Beginning Balance	22,598	23,514
Charge-offs	(407)	(604)
Recoveries
Provision	378	(81)
Ending Balance	22,569	22,829
Ending Balance: Individually Evaluated for Impairment	385	1,757
Ending Balance: Collectively Evaluated for Impairment	22,184	21,072
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality	0
Commercial Construction [Member]
Summary of changes in allowance for loan losses
Beginning Balance	2,811	2,076
Charge-offs
Recoveries
Provision	328	157
Ending Balance	3,139	2,233
Ending Balance: Individually Evaluated for Impairment	0	0
Ending Balance: Collectively Evaluated for Impairment	3,139	2,233
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality	0
Small Business [Member]
Summary of changes in allowance for loan losses
Beginning Balance	1,524	1,896
Charge-offs	(145)	(170)
Recoveries	39	52
Provision	(174)	(319)
Ending Balance	1,244	1,459
Ending Balance: Individually Evaluated for Impairment	113	184
Ending Balance: Collectively Evaluated for Impairment	1,131	1,275
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality	0
Residential Real Estate [Member]
Summary of changes in allowance for loan losses
Beginning Balance	2,930	3,113
Charge-offs	(61)	(109)
Recoveries
Provision	179	68
Ending Balance	3,048	3,072
Ending Balance: Individually Evaluated for Impairment	1,577	1,215
Ending Balance: Collectively Evaluated for Impairment	1,471	1,857
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality	0
Consumer Home Equity [Member]
Summary of changes in allowance for loan losses
Beginning Balance	7,703	4,597
Charge-offs	(277)	(750)
Recoveries	21	13
Provision	269	2,217
Ending Balance	7,716	6,077
Ending Balance: Individually Evaluated for Impairment	58	32
Ending Balance: Collectively Evaluated for Impairment	7,658	6,045
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality	0
Consumer Other [Member]
Summary of changes in allowance for loan losses
Beginning Balance	807	1,382
Charge-offs	(261)	(297)
Recoveries	150	160
Provision	51	(29)
Ending Balance	747	1,216
Ending Balance: Individually Evaluated for Impairment	119	200
Ending Balance: Collectively Evaluated for Impairment	628	1,016
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality	$ 0