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	9 Months Ended	12 Months Ended
	Sep. 30, 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	8,500	10,000
Charge offs	(35,318)	(88,061)
Recoveries	24,765	48,967
Loans and Leases Receivable, Allowance, Ending Balance	266,262	268,315
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	19,981	13,637
Ending balance impaired loans collectively evaluated for impairment	33,770	38,238
Total Impaired Loans, Related Allowance	53,751	51,875
Ending balance all other loans collectively evaluated for impairment	212,511	216,440
Loans and Leases Receivable, Allowance, Total	266,262	268,315
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	103,752	101,686
Ending balance impaired loans collectively evaluated for impairment	184,989	207,727
Total Impaired Loans, Recorded Investment	288,741	309,413
Ending balance all other loans collectively evaluated for impairment	16,870,349	15,586,848
Total loans	17,159,090	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	18,700	12,930
Charge offs	(11,421)	(35,146)
Recoveries	9,501	28,865
Loans and Leases Receivable, Allowance, Ending Balance	121,281	104,501
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	14,006	7,994
Ending balance impaired loans collectively evaluated for impairment	3,590	3,923
Total Impaired Loans, Related Allowance	17,596	11,917
Ending balance all other loans collectively evaluated for impairment	103,685	92,584
Loans and Leases Receivable, Allowance, Total	121,281	104,501
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	45,242	29,343
Ending balance impaired loans collectively evaluated for impairment	42,856	40,893
Total Impaired Loans, Recorded Investment	88,098	70,236
Ending balance all other loans collectively evaluated for impairment	5,515,801	4,752,444
Total loans	5,603,899	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	1,098	(1,778)
Charge offs	(2,963)	(6,474)
Recoveries	1,427	339
Loans and Leases Receivable, Allowance, Ending Balance	19,038	19,476
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	1,672	1,019
Ending balance impaired loans collectively evaluated for impairment	2,404	1,936
Total Impaired Loans, Related Allowance	4,076	2,955
Ending balance all other loans collectively evaluated for impairment	14,962	16,521
Loans and Leases Receivable, Allowance, Total	19,038	19,476
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	17,927	24,744
Ending balance impaired loans collectively evaluated for impairment	17,987	17,929
Total Impaired Loans, Recorded Investment	35,914	42,673
Ending balance all other loans collectively evaluated for impairment	978,421	1,072,042
Total loans	1,014,335	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	777	(1,429)
Charge offs	(29)	(206)
Recoveries	6	218
Loans and Leases Receivable, Allowance, Ending Balance	2,361	1,607
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	735	0
Ending balance impaired loans collectively evaluated for impairment	4	29
Total Impaired Loans, Related Allowance	739	29
Ending balance all other loans collectively evaluated for impairment	1,622	1,578
Loans and Leases Receivable, Allowance, Total	2,361	1,607
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	1,938	0
Ending balance impaired loans collectively evaluated for impairment	9	69
Total Impaired Loans, Recorded Investment	1,947	69
Ending balance all other loans collectively evaluated for impairment	50,653	55,414
Total loans	52,600	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	(14,292)	(2,140)
Charge offs	(4,358)	(9,846)
Recoveries	9,693	6,961
Loans and Leases Receivable, Allowance, Ending Balance	49,199	58,156
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	1,829	3,932
Ending balance impaired loans collectively evaluated for impairment	2,429	3,963
Total Impaired Loans, Related Allowance	4,258	7,895
Ending balance all other loans collectively evaluated for impairment	44,941	50,261
Loans and Leases Receivable, Allowance, Total	49,199	58,156
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	21,204	32,367
Ending balance impaired loans collectively evaluated for impairment	28,342	50,175
Total Impaired Loans, Recorded Investment	49,546	82,542
Ending balance all other loans collectively evaluated for impairment	2,993,815	2,856,914
Total loans	3,043,361	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	(3,831)	541
Charge offs	(1,761)	(3,375)
Recoveries	503	5,511
Loans and Leases Receivable, Allowance, Ending Balance	18,329	23,418
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	1,140	254
Ending balance impaired loans collectively evaluated for impairment	1,021	2,162
Total Impaired Loans, Related Allowance	2,161	2,416
Ending balance all other loans collectively evaluated for impairment	16,168	21,002
Loans and Leases Receivable, Allowance, Total	18,329	23,418
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	6,026	3,777
Ending balance impaired loans collectively evaluated for impairment	2,966	6,483
Total Impaired Loans, Recorded Investment	8,992	10,260
Ending balance all other loans collectively evaluated for impairment	973,434	885,988
Total loans	982,426	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	1,278	(8,213)
Charge offs	(9,713)	(20,629)
Recoveries	2,546	4,212
Loans and Leases Receivable, Allowance, Ending Balance	26,307	32,196
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	11	123
Ending balance impaired loans collectively evaluated for impairment	12,480	13,866
Total Impaired Loans, Related Allowance	12,491	13,989
Ending balance all other loans collectively evaluated for impairment	13,816	18,207
Loans and Leases Receivable, Allowance, Total	26,307	32,196
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	1,025	929
Ending balance impaired loans collectively evaluated for impairment	30,818	33,871
Total Impaired Loans, Recorded Investment	31,843	34,800
Ending balance all other loans collectively evaluated for impairment	1,644,682	1,790,214
Total loans	1,676,525	1,825,014
Installment and Credit Cards Portfolio 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	3,486	(2,127)
Charge offs	(1,751)	(1,389)
Recoveries	481	1,633
Loans and Leases Receivable, Allowance, Ending Balance	4,632	2,416
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	0	0
Ending balance impaired loans collectively evaluated for impairment	339	487
Total Impaired Loans, Related Allowance	339	487
Ending balance all other loans collectively evaluated for impairment	4,293	1,929
Loans and Leases Receivable, Allowance, Total	4,632	2,416
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	0	0
Ending balance impaired loans collectively evaluated for impairment	1,759	1,360
Total Impaired Loans, Recorded Investment	1,759	1,360
Ending balance all other loans collectively evaluated for impairment	457,923	405,714
Total loans	459,682	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	1,284	12,216
Charge offs	(3,322)	(10,996)
Recoveries	608	1,228
Loans and Leases Receivable, Allowance, Ending Balance	25,115	26,545
Allowance for loan losses:
Ending balance impaired loans individually evaluated for impairment	588	315
Ending balance impaired loans collectively evaluated for impairment	11,503	11,872
Total Impaired Loans, Related Allowance	12,091	12,187
Ending balance all other loans collectively evaluated for impairment	13,024	14,358
Loans and Leases Receivable, Allowance, Total	25,115	26,545
Loans [Abstract]
Ending balance impaired loans individually evaluated for impairment	10,390	10,526
Ending balance impaired loans collectively evaluated for impairment	60,252	56,947
Total Impaired Loans, Recorded Investment	70,642	67,473
Ending balance all other loans collectively evaluated for impairment	4,255,620	3,768,118
Total loans	$ 4,326,262	$ 3,835,591