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	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	$ 297,409	$ 378,151	$ 476,813
Provision for loan losses	10,000	3,000	52,000
Charge offs	(88,061)	(117,046)	(189,732)
Recoveries	48,967	33,304	39,070
Loans and Leases Receivable, Allowance, Ending Balance	268,315	297,409	378,151
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	13,637	16,787
Ending balance impaired loans collectively evaluated for impairment	38,238	52,504
Ending balance all other loans collectively evaluated for impairment	216,440	228,118
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	101,686	132,528
Ending balance impaired loans collectively evaluated for impairment	207,727	241,427
Ending balance all other loans collectively evaluated for impairment	15,586,848	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
Provision for loan losses	12,930	(1,645)
Charge offs	(35,146)	(43,240)
Recoveries	28,865	18,363
Loans and Leases Receivable, Allowance, Ending Balance	104,501	97,852
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	7,994	8,790
Ending balance impaired loans collectively evaluated for impairment	3,923	4,951
Ending balance all other loans collectively evaluated for impairment	92,584	84,111
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	29,343	27,213
Ending balance impaired loans collectively evaluated for impairment	40,893	40,109
Ending balance all other loans collectively evaluated for impairment	4,752,444	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
Provision for loan losses	(1,778)	(5,184)
Charge offs	(6,474)	(4,080)
Recoveries	339	453
Loans and Leases Receivable, Allowance, Ending Balance	19,476	27,389
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	1,019	654
Ending balance impaired loans collectively evaluated for impairment	1,936	3,157
Ending balance all other loans collectively evaluated for impairment	16,521	23,578
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	24,744	16,602
Ending balance impaired loans collectively evaluated for impairment	17,929	21,504
Ending balance all other loans collectively evaluated for impairment	1,072,042	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
Provision for loan losses	(1,429)	(645)
Charge offs	(206)	(797)
Recoveries	218	1,899
Loans and Leases Receivable, Allowance, Ending Balance	1,607	3,024
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	0	0
Ending balance impaired loans collectively evaluated for impairment	29	0
Ending balance all other loans collectively evaluated for impairment	1,578	3,024
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	0	3,024
Ending balance impaired loans collectively evaluated for impairment	69	7
Ending balance all other loans collectively evaluated for impairment	55,414	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
Provision for loan losses	(2,140)	(14,304)
Charge offs	(9,846)	(14,000)
Recoveries	6,961	4,796
Loans and Leases Receivable, Allowance, Ending Balance	58,156	63,181
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	3,932	5,241
Ending balance impaired loans collectively evaluated for impairment	3,963	4,446
Ending balance all other loans collectively evaluated for impairment	50,261	53,494
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	32,367	48,894
Ending balance impaired loans collectively evaluated for impairment	50,175	51,453
Ending balance all other loans collectively evaluated for impairment	2,856,914	2,806,412
Real Estate Construction Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	20,741	21,327
Provision for loan losses	541	873
Charge offs	(3,375)	(3,588)
Recoveries	5,511	2,129
Loans and Leases Receivable, Allowance, Ending Balance	23,418	20,741
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	254	1,079
Ending balance impaired loans collectively evaluated for impairment	2,162	2,332
Ending balance all other loans collectively evaluated for impairment	21,002	17,330
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	3,777	20,794
Ending balance impaired loans collectively evaluated for impairment	6,483	11,038
Ending balance all other loans collectively evaluated for impairment	885,988	623,549
Home Equity Portfolio Segments [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	56,826	70,144
Provision for loan losses	(8,213)	16,909
Charge offs	(20,629)	(34,125)
Recoveries	4,212	3,898
Loans and Leases Receivable, Allowance, Ending Balance	32,196	56,826
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	123	868
Ending balance impaired loans collectively evaluated for impairment	13,866	23,712
Ending balance all other loans collectively evaluated for impairment	18,207	32,246
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	929	4,671
Ending balance impaired loans collectively evaluated for impairment	33,871	44,512
Ending balance all other loans collectively evaluated for impairment	1,790,214	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
Provision for loan losses	(2,127)	(501)
Charge offs	(1,389)	(3,057)
Recoveries	1,633	1,234
Loans and Leases Receivable, Allowance, Ending Balance	2,416	4,299
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	0	0
Ending balance impaired loans collectively evaluated for impairment	487	1,155
Ending balance all other loans collectively evaluated for impairment	1,929	3,144
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	0	0
Ending balance impaired loans collectively evaluated for impairment	1,360	2,491
Ending balance all other loans collectively evaluated for impairment	405,714	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
Provision for loan losses	12,216	7,497
Charge offs	(10,996)	(14,159)
Recoveries	1,228	532
Loans and Leases Receivable, Allowance, Ending Balance	26,545	24,097
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	315	155
Ending balance impaired loans collectively evaluated for impairment	11,872	12,751
Ending balance all other loans collectively evaluated for impairment	14,358	11,191
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	10,526	11,330
Ending balance impaired loans collectively evaluated for impairment	56,947	70,313
Ending balance all other loans collectively evaluated for impairment	$ 3,768,118	$ 3,295,054