Loans, Allowance for Loan Losses, and Credit Quality (Details 2) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	$ 378,151	$ 476,813
Provision for loan losses	0	52,000
Charge offs	(86,629)	(189,732)
Recoveries	23,628	39,070
Loans and Leases Receivable, Allowance, Ending Balance	315,150	378,151
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	22,541	36,809
Ending balance impaired loans collectively evaluated for impairment	63,280	67,970
Ending balance all other loans collectively evaluated for impairment	229,329	273,372
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	151,927	215,478
Ending balance impaired loans collectively evaluated for impairment	262,036	254,458
Ending balance all other loans collectively evaluated for impairment	14,552,251	13,561,135
Commercial and Industrial Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	124,374	137,770
Provision for loan losses	8,943	8,916
Charge offs	(35,830)	(38,662)
Recoveries	13,583	16,350
Loans and Leases Receivable, Allowance, Ending Balance	111,070	124,374
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	7,814	7,619
Ending balance impaired loans collectively evaluated for impairment	7,578	7,688
Ending balance all other loans collectively evaluated for impairment	95,678	109,067
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	28,409	41,474
Ending balance impaired loans collectively evaluated for impairment	48,300	37,153
Ending balance all other loans collectively evaluated for impairment	4,188,647	3,646,109
Commercial Real Estate Owner Occupied Portfolio [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	36,200	54,320
Provision for loan losses	(2,492)	(11,144)
Charge offs	(2,402)	(9,485)
Recoveries	831	2,509
Loans and Leases Receivable, Allowance, Ending Balance	32,137	36,200
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	1,042	3,608
Ending balance impaired loans collectively evaluated for impairment	4,721	3,962
Ending balance all other loans collectively evaluated for impairment	26,374	28,630
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	17,372	26,049
Ending balance impaired loans collectively evaluated for impairment	25,495	17,807
Ending balance all other loans collectively evaluated for impairment	1,154,650	1,042,973
Finance Leases Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	2,567	7,396
Provision for loan losses	(1,677)	(6,611)
Charge offs	(21)	(173)
Recoveries	1,877	1,955
Loans and Leases Receivable, Allowance, Ending Balance	2,746	2,567
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	0	161
Ending balance impaired loans collectively evaluated for impairment	22	34
Ending balance all other loans collectively evaluated for impairment	2,724	2,372
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	5,386	9,792
Ending balance impaired loans collectively evaluated for impairment	541	852
Ending balance all other loans collectively evaluated for impairment	54,891	47,550
Commercial Real Estate Investor Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	86,689	111,264
Provision for loan losses	(11,965)	(762)
Charge offs	(10,968)	(29,479)
Recoveries	1,532	5,666
Loans and Leases Receivable, Allowance, Ending Balance	65,288	86,689
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	8,759	16,623
Ending balance impaired loans collectively evaluated for impairment	7,507	8,378
Ending balance all other loans collectively evaluated for impairment	49,022	61,688
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	59,441	85,287
Ending balance impaired loans collectively evaluated for impairment	61,330	57,482
Ending balance all other loans collectively evaluated for impairment	2,666,387	2,420,998
Real Estate Construction Port Folio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	21,327	56,772
Provision for loan losses	(6,684)	(4,744)
Charge offs	(2,139)	(38,222)
Recoveries	1,538	7,521
Loans and Leases Receivable, Allowance, Ending Balance	14,042	21,327
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	1,653	4,919
Ending balance impaired loans collectively evaluated for impairment	3,072	4,266
Ending balance all other loans collectively evaluated for impairment	9,317	12,142
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	24,359	31,933
Ending balance impaired loans collectively evaluated for impairment	10,886	20,850
Ending balance all other loans collectively evaluated for impairment	575,941	531,263
Home Equity Port Folio Segments [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	70,144	55,090
Provision for loan losses	6,293	54,476
Charge offs	(25,146)	(42,623)
Recoveries	2,990	3,201
Loans and Leases Receivable, Allowance, Ending Balance	54,281	70,144
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	888	2,922
Ending balance impaired loans collectively evaluated for impairment	24,343	27,914
Ending balance all other loans collectively evaluated for impairment	29,050	39,308
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	4,880	9,542
Ending balance impaired loans collectively evaluated for impairment	43,054	46,315
Ending balance all other loans collectively evaluated for impairment	2,308,966	2,448,847
Installment Port Folio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	6,623	17,328
Provision for loan losses	163	3,845
Charge offs	(1,763)	(16,134)
Recoveries	967	1,584
Loans and Leases Receivable, Allowance, Ending Balance	5,990	6,623
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	515	0
Ending balance impaired loans collectively evaluated for impairment	1,796	2,021
Ending balance all other loans collectively evaluated for impairment	3,679	4,602
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	515	0
Ending balance impaired loans collectively evaluated for impairment	3,050	3,730
Ending balance all other loans collectively evaluated for impairment	478,886	554,052
Residential Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	30,227	36,873
Provision for loan losses	7,419	8,024
Charge offs	(8,360)	(14,954)
Recoveries	310	284
Loans and Leases Receivable, Allowance, Ending Balance	29,596	30,227
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	1,870	957
Ending balance impaired loans collectively evaluated for impairment	14,241	13,707
Ending balance all other loans collectively evaluated for impairment	13,485	15,563
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	11,565	11,401
Ending balance impaired loans collectively evaluated for impairment	69,380	70,269
Ending balance all other loans collectively evaluated for impairment	$ 3,123,883	$ 2,869,343