Allowance for Loan Losses Allowance Rollforward (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	$ 84,057	$ 96,114
Provision/ (Credit) for loan losses	0	4,000
Financing Receivable, Allowance for Credit Losses, Charge-offs	2,893	2,941
Financing Receivable, Allowance for Credit Losses, Recoveries	1,122	729
Loans and Leases Receivable, Allowance at End of Period	82,286	97,902
Commercial and industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	11,825	12,163
Provision/ (Credit) for loan losses	(114)	1,827
Financing Receivable, Allowance for Credit Losses, Charge-offs	27	2,311
Financing Receivable, Allowance for Credit Losses, Recoveries	165	383
Loans and Leases Receivable, Allowance at End of Period	11,849	12,062
Commercial real estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	52,497	63,625
Provision/ (Credit) for loan losses	(919)	2,030
Financing Receivable, Allowance for Credit Losses, Charge-offs	1,239	406
Financing Receivable, Allowance for Credit Losses, Recoveries	127	117
Loans and Leases Receivable, Allowance at End of Period	50,466	65,366
Construction and land [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	5,016	6,382
Provision/ (Credit) for loan losses	(1,036)	(712)
Financing Receivable, Allowance for Credit Losses, Charge-offs	0	0
Financing Receivable, Allowance for Credit Losses, Recoveries	807	166
Loans and Leases Receivable, Allowance at End of Period	4,787	5,836
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	10,892	9,286
Provision/ (Credit) for loan losses	1,827	966
Financing Receivable, Allowance for Credit Losses, Charge-offs	1,265	198
Financing Receivable, Allowance for Credit Losses, Recoveries	0	0
Loans and Leases Receivable, Allowance at End of Period	11,454	10,054
Home equity [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	1,085	1,535
Provision/ (Credit) for loan losses	398	(53)
Financing Receivable, Allowance for Credit Losses, Charge-offs	360	0
Financing Receivable, Allowance for Credit Losses, Recoveries	23	61
Loans and Leases Receivable, Allowance at End of Period	1,146	1,543
Consumer and other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	540	1,149
Provision/ (Credit) for loan losses	(74)	(116)
Financing Receivable, Allowance for Credit Losses, Charge-offs	2	26
Financing Receivable, Allowance for Credit Losses, Recoveries	0	2
Loans and Leases Receivable, Allowance at End of Period	464	1,009
Unallocated Financing Receivables [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Allowance at Beginning of Period	2,202	1,974
Provision/ (Credit) for loan losses	(82)	58
Loans and Leases Receivable, Allowance at End of Period	$ 2,120	$ 2,032