Loans, Allowance for Loan Losses, and Credit Quality Changes in the Allowance for Loan Losses by Portfolio Segment (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance			$ 297,409	$ 378,151	$ 378,151
Provision for loan losses	0	0	8,000	0	3,000
Charge offs			(69,320)		(117,046)
Recoveries			35,635		33,304
Loans and Leases Receivable, Allowance, Ending Balance	271,724		271,724		297,409
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	8,569		8,569		16,787
Ending balance impaired loans collectively evaluated for impairment	40,858		40,858		52,504
Ending balance all other loans collectively evaluated for impairment	222,297		222,297		228,118
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	115,365		115,365		132,528
Ending balance impaired loans collectively evaluated for impairment	209,272		209,272		241,427
Ending balance all other loans collectively evaluated for impairment	15,261,217		15,261,217		15,037,067
Commercial and Industrial Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance			97,852	124,374	124,374
Provision for loan losses			5,765		(1,645)
Charge offs			(25,091)		(43,240)
Recoveries			23,365		18,363
Loans and Leases Receivable, Allowance, Ending Balance	101,891		101,891		97,852
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	2,986		2,986		8,790
Ending balance impaired loans collectively evaluated for impairment	5,146		5,146		4,951
Ending balance all other loans collectively evaluated for impairment	93,759		93,759		84,111
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	24,931		24,931		27,213
Ending balance impaired loans collectively evaluated for impairment	43,319		43,319		40,109
Ending balance all other loans collectively evaluated for impairment	4,634,806		4,634,806		4,434,699
Commercial Real Estate Owner Occupied Portfolio [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance			27,389	36,200	36,200
Provision for loan losses			(381)		(5,184)
Charge offs			(5,384)		(4,080)
Recoveries			216		453
Loans and Leases Receivable, Allowance, Ending Balance	21,840		21,840		27,389
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	992		992		654
Ending balance impaired loans collectively evaluated for impairment	2,700		2,700		3,157
Ending balance all other loans collectively evaluated for impairment	18,148		18,148		23,578
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	21,160		21,160		16,602
Ending balance impaired loans collectively evaluated for impairment	21,566		21,566		21,504
Ending balance all other loans collectively evaluated for impairment	1,104,626		1,104,626		1,181,641
Finance Leases Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance			3,024	2,567	2,567
Provision for loan losses			(1,507)		(645)
Charge offs			(206)		(797)
Recoveries			202		1,899
Loans and Leases Receivable, Allowance, Ending Balance	1,513		1,513		3,024
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	0		0		0
Ending balance impaired loans collectively evaluated for impairment	41		41		0
Ending balance all other loans collectively evaluated for impairment	1,472		1,472		3,024
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	0		0		3,024
Ending balance impaired loans collectively evaluated for impairment	99		99		7
Ending balance all other loans collectively evaluated for impairment	51,628		51,628		61,165
Commercial Real Estate Investor Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance			63,181	86,689	86,689
Provision for loan losses			671		(14,304)
Charge offs			(7,376)		(14,000)
Recoveries			4,628		4,796
Loans and Leases Receivable, Allowance, Ending Balance	61,104		61,104		63,181
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	4,031		4,031		5,241
Ending balance impaired loans collectively evaluated for impairment	4,297		4,297		4,446
Ending balance all other loans collectively evaluated for impairment	52,776		52,776		53,494
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	43,513		43,513		48,894
Ending balance impaired loans collectively evaluated for impairment	41,401		41,401		51,453
Ending balance all other loans collectively evaluated for impairment	2,762,238		2,762,238		2,806,412
Real Estate Construction Port Folio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance			20,741	21,327	21,327
Provision for loan losses			4,079		873
Charge offs			(3,147)		(3,588)
Recoveries			2,153		2,129
Loans and Leases Receivable, Allowance, Ending Balance	23,826		23,826		20,741
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	265		265		1,079
Ending balance impaired loans collectively evaluated for impairment	2,642		2,642		2,332
Ending balance all other loans collectively evaluated for impairment	20,919		20,919		17,330
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	15,152		15,152		20,794
Ending balance impaired loans collectively evaluated for impairment	8,343		8,343		11,038
Ending balance all other loans collectively evaluated for impairment	811,249		811,249		623,549
Home Equity Port Folio Segments [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance			56,826	70,144	70,144
Provision for loan losses			(10,325)		16,909
Charge offs			(17,251)		(34,125)
Recoveries			3,283		3,898
Loans and Leases Receivable, Allowance, Ending Balance	32,533		32,533		56,826
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	130		130		868
Ending balance impaired loans collectively evaluated for impairment	13,689		13,689		23,712
Ending balance all other loans collectively evaluated for impairment	18,714		18,714		32,246
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	990		990		4,671
Ending balance impaired loans collectively evaluated for impairment	34,312		34,312		44,512
Ending balance all other loans collectively evaluated for impairment	1,856,076		1,856,076		2,170,311
Installment Port Folio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance			4,299	6,623	6,623
Provision for loan losses			(1,383)		(501)
Charge offs			(1,065)		(3,057)
Recoveries			698		1,234
Loans and Leases Receivable, Allowance, Ending Balance	2,549		2,549		4,299
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	0		0		0
Ending balance impaired loans collectively evaluated for impairment	557		557		1,155
Ending balance all other loans collectively evaluated for impairment	1,992		1,992		3,144
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	0		0		0
Ending balance impaired loans collectively evaluated for impairment	1,685		1,685		2,491
Ending balance all other loans collectively evaluated for impairment	418,583		418,583		464,236
Residential Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance			24,097	30,227	30,227
Provision for loan losses			11,081		7,497
Charge offs			(9,800)		(14,159)
Recoveries			1,090		532
Loans and Leases Receivable, Allowance, Ending Balance	26,468		26,468		24,097
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	165		165		155
Ending balance impaired loans collectively evaluated for impairment	11,786		11,786		12,751
Ending balance all other loans collectively evaluated for impairment	14,517		14,517		11,191
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	9,619		9,619		11,330
Ending balance impaired loans collectively evaluated for impairment	58,547		58,547		70,313
Ending balance all other loans collectively evaluated for impairment	$ 3,622,011		$ 3,622,011		$ 3,295,054