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	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	$ 268,315	$ 297,409
Provision for loan losses	5,000	10,000
Charge offs	(11,361)	(88,061)
Recoveries	5,962	48,967
Loans and Leases Receivable, Allowance, Ending Balance	267,916	268,315
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	12,749	13,637
Ending balance impaired loans collectively evaluated for impairment	37,060	38,238
Total Impaired Loans, Related Allowance	49,809	51,875
Ending balance all other loans collectively evaluated for impairment	218,107	216,440
Loans and Leases Receivable, Allowance, Total	267,916	268,315
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	96,219	101,686
Ending balance impaired loans collectively evaluated for impairment	198,683	207,727
Total Impaired Loans, Recorded Investment	294,902	309,413
Ending balance all other loans collectively evaluated for impairment	16,146,542	15,586,848
Total loans	16,441,444	15,896,261
Commercial and Industrial Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	104,501	97,852
Provision for loan losses	9,593	12,930
Charge offs	(5,334)	(35,146)
Recoveries	2,609	28,865
Loans and Leases Receivable, Allowance, Ending Balance	111,369	104,501
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	6,978	7,994
Ending balance impaired loans collectively evaluated for impairment	3,667	3,923
Total Impaired Loans, Related Allowance	10,645	11,917
Ending balance all other loans collectively evaluated for impairment	100,724	92,584
Loans and Leases Receivable, Allowance, Total	111,369	104,501
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	31,526	29,343
Ending balance impaired loans collectively evaluated for impairment	34,738	40,893
Total Impaired Loans, Recorded Investment	66,264	70,236
Ending balance all other loans collectively evaluated for impairment	5,155,877	4,752,444
Total loans	5,222,141	4,822,680
Commercial Real Estate Owner Occupied Portfolio [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	19,476	27,389
Provision for loan losses	(97)	(1,778)
Charge offs	(163)	(6,474)
Recoveries	287	339
Loans and Leases Receivable, Allowance, Ending Balance	19,503	19,476
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	1,322	1,019
Ending balance impaired loans collectively evaluated for impairment	1,864	1,936
Total Impaired Loans, Related Allowance	3,186	2,955
Ending balance all other loans collectively evaluated for impairment	16,317	16,521
Loans and Leases Receivable, Allowance, Total	19,503	19,476
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	21,580	24,744
Ending balance impaired loans collectively evaluated for impairment	16,734	17,929
Total Impaired Loans, Recorded Investment	38,314	42,673
Ending balance all other loans collectively evaluated for impairment	1,059,775	1,072,042
Total loans	1,098,089	1,114,715
Finance Leases Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	1,607	3,024
Provision for loan losses	374	(1,429)
Charge offs	0	(206)
Recoveries	0	218
Loans and Leases Receivable, Allowance, Ending Balance	1,981	1,607
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	0	0
Ending balance impaired loans collectively evaluated for impairment	69	29
Total Impaired Loans, Related Allowance	69	29
Ending balance all other loans collectively evaluated for impairment	1,912	1,578
Loans and Leases Receivable, Allowance, Total	1,981	1,607
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	0	0
Ending balance impaired loans collectively evaluated for impairment	172	69
Total Impaired Loans, Recorded Investment	172	69
Ending balance all other loans collectively evaluated for impairment	52,328	55,414
Total loans	52,500	55,483
Commercial Real Estate Investor Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	58,156	63,181
Provision for loan losses	(3,325)	(2,140)
Charge offs	(302)	(9,846)
Recoveries	1,333	6,961
Loans and Leases Receivable, Allowance, Ending Balance	55,862	58,156
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	3,983	3,932
Ending balance impaired loans collectively evaluated for impairment	4,141	3,963
Total Impaired Loans, Related Allowance	8,124	7,895
Ending balance all other loans collectively evaluated for impairment	47,738	50,261
Loans and Leases Receivable, Allowance, Total	55,862	58,156
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	28,790	32,367
Ending balance impaired loans collectively evaluated for impairment	50,841	50,175
Total Impaired Loans, Recorded Investment	79,631	82,542
Ending balance all other loans collectively evaluated for impairment	2,921,588	2,856,914
Total loans	3,001,219	2,939,456
Real Estate Construction Port Folio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	23,418	20,741
Provision for loan losses	(2,341)	541
Charge offs	(271)	(3,375)
Recoveries	158	5,511
Loans and Leases Receivable, Allowance, Ending Balance	20,964	23,418
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	203	254
Ending balance impaired loans collectively evaluated for impairment	1,947	2,162
Total Impaired Loans, Related Allowance	2,150	2,416
Ending balance all other loans collectively evaluated for impairment	18,814	21,002
Loans and Leases Receivable, Allowance, Total	20,964	23,418
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	3,930	3,777
Ending balance impaired loans collectively evaluated for impairment	5,691	6,483
Total Impaired Loans, Recorded Investment	9,621	10,260
Ending balance all other loans collectively evaluated for impairment	959,996	885,988
Total loans	969,617	896,248
Home Equity Port Folio Segments [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	32,196	56,826
Provision for loan losses	495	(8,213)
Charge offs	(3,581)	(20,629)
Recoveries	1,134	4,212
Loans and Leases Receivable, Allowance, Ending Balance	30,244	32,196
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	4	123
Ending balance impaired loans collectively evaluated for impairment	13,095	13,866
Total Impaired Loans, Related Allowance	13,099	13,989
Ending balance all other loans collectively evaluated for impairment	17,145	18,207
Loans and Leases Receivable, Allowance, Total	30,244	32,196
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	427	929
Ending balance impaired loans collectively evaluated for impairment	31,630	33,871
Total Impaired Loans, Recorded Investment	32,057	34,800
Ending balance all other loans collectively evaluated for impairment	1,729,945	1,790,214
Total loans	1,762,002	1,825,014
Installment Port Folio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	2,416	4,299
Provision for loan losses	96	(2,127)
Charge offs	(307)	(1,389)
Recoveries	194	1,633
Loans and Leases Receivable, Allowance, Ending Balance	2,399	2,416
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	0	0
Ending balance impaired loans collectively evaluated for impairment	448	487
Total Impaired Loans, Related Allowance	448	487
Ending balance all other loans collectively evaluated for impairment	1,951	1,929
Loans and Leases Receivable, Allowance, Total	2,399	2,416
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	0	0
Ending balance impaired loans collectively evaluated for impairment	1,140	1,360
Total Impaired Loans, Recorded Investment	1,140	1,360
Ending balance all other loans collectively evaluated for impairment	392,181	405,714
Total loans	393,321	407,074
Residential Portfolio Segment [Member]
Changes in the allowance for loan losses by portfolio segment
Loans and Leases Receivable, Allowance, Beginning Balance	26,545	24,097
Provision for loan losses	205	12,216
Charge offs	(1,403)	(10,996)
Recoveries	247	1,228
Loans and Leases Receivable, Allowance, Ending Balance	25,594	26,545
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	259	315
Ending balance impaired loans collectively evaluated for impairment	11,829	11,872
Total Impaired Loans, Related Allowance	12,088	12,187
Ending balance all other loans collectively evaluated for impairment	13,506	14,358
Loans and Leases Receivable, Allowance, Total	25,594	26,545
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	9,966	10,526
Ending balance impaired loans collectively evaluated for impairment	57,737	56,947
Total Impaired Loans, Recorded Investment	67,703	67,473
Ending balance all other loans collectively evaluated for impairment	3,874,852	3,768,118
Total loans	$ 3,942,555	$ 3,835,591