Loans, Allowance for Loan Losses, and Credit Quality Loans by Past Due Status (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Summarized details of Loans
30-59 Days Past Due	$ 40,350	$ 43,388
60-89 Days Past Due	17,673	33,281
90 Days or More Past Due	64,076	86,863
Total Past Due	122,099	163,532
Current	16,319,345	15,732,729
Total loans	16,441,444	15,896,261
Commercial And Industrial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	6,879	4,388
60-89 Days Past Due	2,255	5,200
90 Days or More Past Due	4,147	10,964
Total Past Due	13,281	20,552
Current	5,208,860	4,802,128
Total loans	5,222,141	4,822,680
Commercial Real Estate Owner Occupied Portfolio [Member]
Summarized details of Loans
30-59 Days Past Due	6,332	3,497
60-89 Days Past Due	1,037	3,815
90 Days or More Past Due	3,641	11,125
Total Past Due	11,010	18,437
Current	1,087,079	1,096,278
Total loans	1,098,089	1,114,715
Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	596	0
60-89 Days Past Due	0	0
90 Days or More Past Due	10	69
Total Past Due	606	69
Current	51,894	55,414
Total loans	52,500	55,483
Commercial And Business Lending [Member]
Summarized details of Loans
30-59 Days Past Due	13,807	7,885
60-89 Days Past Due	3,292	9,015
90 Days or More Past Due	7,798	22,158
Total Past Due	24,897	39,058
Current	6,347,833	5,953,820
Total loans	6,372,730	5,992,878
Commercial Real Estate Investor Portfolio Segment [Member]
Summarized details of Loans
30-59 Days Past Due	7,414	12,489
60-89 Days Past Due	5,521	15,033
90 Days or More Past Due	17,037	20,466
Total Past Due	29,972	47,988
Current	2,971,247	2,891,468
Total loans	3,001,219	2,939,456
Commercial Real Estate Construction Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	316	3,212
60-89 Days Past Due	408	1,118
90 Days or More Past Due	2,529	2,267
Total Past Due	3,253	6,597
Current	966,364	889,651
Total loans	969,617	896,248
Commercial Real Estate Lending [Member]
Summarized details of Loans
30-59 Days Past Due	7,730	15,701
60-89 Days Past Due	5,929	16,151
90 Days or More Past Due	19,566	22,733
Total Past Due	33,225	54,585
Current	3,937,611	3,781,119
Total loans	3,970,836	3,835,704
Commercial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	21,537	23,586
60-89 Days Past Due	9,221	25,166
90 Days or More Past Due	27,364	44,891
Total Past Due	58,122	93,643
Current	10,285,444	9,734,939
Total loans	10,343,566	9,828,582
Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	9,938	10,336
60-89 Days Past Due	3,921	3,704
90 Days or More Past Due	11,746	14,677
Total Past Due	25,605	28,717
Current	1,736,397	1,796,297
Total loans	1,762,002	1,825,014
Installment [Member]
Summarized details of Loans
30-59 Days Past Due	1,090	1,014
60-89 Days Past Due	465	289
90 Days or More Past Due	719	926
Total Past Due	2,274	2,229
Current	391,047	404,845
Total loans	393,321	407,074
Residential, Prime, Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	7,785	8,452
60-89 Days Past Due	4,066	4,122
90 Days or More Past Due	24,247	26,369
Total Past Due	36,098	38,943
Current	3,906,457	3,796,648
Total loans	3,942,555	3,835,591
Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	18,813	19,802
60-89 Days Past Due	8,452	8,115
90 Days or More Past Due	36,712	41,972
Total Past Due	63,977	69,889
Current	6,033,901	5,997,790
Total loans	6,097,878	6,067,679
Accruing Loans [Member]
Summarized details of Loans
30-59 Days Past Due	28,306	29,071
60-89 Days Past Due	5,182	23,978
90 Days or More Past Due	723	2,350
Total Past Due	34,211	55,399
Current	16,229,255	15,655,434
Total loans	16,263,466	15,710,833
Accruing Loans [Member] | Commercial And Industrial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	3,484	3,390
60-89 Days Past Due	642	3,436
90 Days or More Past Due	16	1,199
Total Past Due	4,142	8,025
Current	5,179,511	4,776,936
Total loans	5,183,653	4,784,961
Accruing Loans [Member] | Commercial Real Estate Owner Occupied Portfolio [Member]
Summarized details of Loans
30-59 Days Past Due	5,292	1,015
60-89 Days Past Due	50	2,091
90 Days or More Past Due	0	0
Total Past Due	5,342	3,106
Current	1,066,012	1,081,945
Total loans	1,071,354	1,085,051
Accruing Loans [Member] | Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	567	0
60-89 Days Past Due	0	0
90 Days or More Past Due	0	0
Total Past Due	567	0
Current	51,761	55,414
Total loans	52,328	55,414
Accruing Loans [Member] | Commercial And Business Lending [Member]
Summarized details of Loans
30-59 Days Past Due	9,343	4,405
60-89 Days Past Due	692	5,527
90 Days or More Past Due	16	1,199
Total Past Due	10,051	11,131
Current	6,297,284	5,914,295
Total loans	6,307,335	5,925,426
Accruing Loans [Member] | Commercial Real Estate Investor Portfolio Segment [Member]
Summarized details of Loans
30-59 Days Past Due	5,582	9,081
60-89 Days Past Due	1,606	14,134
90 Days or More Past Due	0	0
Total Past Due	7,188	23,215
Current	2,960,420	2,878,645
Total loans	2,967,608	2,901,860
Accruing Loans [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	295	836
60-89 Days Past Due	384	1,118
90 Days or More Past Due	0	0
Total Past Due	679	1,954
Current	962,271	887,827
Total loans	962,950	889,781
Accruing Loans [Member] | Commercial Real Estate Lending [Member]
Summarized details of Loans
30-59 Days Past Due	5,877	9,917
60-89 Days Past Due	1,990	15,252
90 Days or More Past Due	0	0
Total Past Due	7,867	25,169
Current	3,922,691	3,766,472
Total loans	3,930,558	3,791,641
Accruing Loans [Member] | Commercial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	15,220	14,322
60-89 Days Past Due	2,682	20,779
90 Days or More Past Due	16	1,199
Total Past Due	17,918	36,300
Current	10,219,975	9,680,767
Total loans	10,237,893	9,717,067
Accruing Loans [Member] | Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	8,114	8,611
60-89 Days Past Due	1,705	2,069
90 Days or More Past Due	68	346
Total Past Due	9,887	11,026
Current	1,729,630	1,788,821
Total loans	1,739,517	1,799,847
Accruing Loans [Member] | Installment [Member]
Summarized details of Loans
30-59 Days Past Due	1,004	885
60-89 Days Past Due	265	265
90 Days or More Past Due	586	637
Total Past Due	1,855	1,787
Current	390,551	404,173
Total loans	392,406	405,960
Accruing Loans [Member] | Residential, Prime, Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	3,968	5,253
60-89 Days Past Due	530	865
90 Days or More Past Due	53	168
Total Past Due	4,551	6,286
Current	3,889,099	3,781,673
Total loans	3,893,650	3,787,959
Accruing Loans [Member] | Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	13,086	14,749
60-89 Days Past Due	2,500	3,199
90 Days or More Past Due	707	1,151
Total Past Due	16,293	19,099
Current	6,009,280	5,974,667
Total loans	6,025,573	5,993,766
Nonaccrual Loan [Member]
Summarized details of Loans
30-59 Days Past Due	12,044	14,317
60-89 Days Past Due	12,491	9,303
90 Days or More Past Due	63,353	84,513
Total Past Due	87,888	108,133
Current	90,090	77,295
Total loans	177,978	185,428
Nonaccrual Loan [Member] | Commercial And Industrial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	3,395	998
60-89 Days Past Due	1,613	1,764
90 Days or More Past Due	4,131	9,765
Total Past Due	9,139	12,527
Current	29,349	25,192
Total loans	38,488	37,719
Nonaccrual Loan [Member] | Commercial Real Estate Owner Occupied Portfolio [Member]
Summarized details of Loans
30-59 Days Past Due	1,040	2,482
60-89 Days Past Due	987	1,724
90 Days or More Past Due	3,641	11,125
Total Past Due	5,668	15,331
Current	21,067	14,333
Total loans	26,735	29,664
Nonaccrual Loan [Member] | Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	29	0
60-89 Days Past Due	0	0
90 Days or More Past Due	10	69
Total Past Due	39	69
Current	133	0
Total loans	172	69
Nonaccrual Loan [Member] | Commercial And Business Lending [Member]
Summarized details of Loans
30-59 Days Past Due	4,464	3,480
60-89 Days Past Due	2,600	3,488
90 Days or More Past Due	7,782	20,959
Total Past Due	14,846	27,927
Current	50,549	39,525
Total loans	65,395	67,452
Nonaccrual Loan [Member] | Commercial Real Estate Investor Portfolio Segment [Member]
Summarized details of Loans
30-59 Days Past Due	1,832	3,408
60-89 Days Past Due	3,915	899
90 Days or More Past Due	17,037	20,466
Total Past Due	22,784	24,773
Current	10,827	12,823
Total loans	33,611	37,596
Nonaccrual Loan [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	21	2,376
60-89 Days Past Due	24	0
90 Days or More Past Due	2,529	2,267
Total Past Due	2,574	4,643
Current	4,093	1,824
Total loans	6,667	6,467
Nonaccrual Loan [Member] | Commercial Real Estate Lending [Member]
Summarized details of Loans
30-59 Days Past Due	1,853	5,784
60-89 Days Past Due	3,939	899
90 Days or More Past Due	19,566	22,733
Total Past Due	25,358	29,416
Current	14,920	14,647
Total loans	40,278	44,063
Nonaccrual Loan [Member] | Commercial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	6,317	9,264
60-89 Days Past Due	6,539	4,387
90 Days or More Past Due	27,348	43,692
Total Past Due	40,204	57,343
Current	65,469	54,172
Total loans	105,673	111,515
Nonaccrual Loan [Member] | Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	1,824	1,725
60-89 Days Past Due	2,216	1,635
90 Days or More Past Due	11,678	14,331
Total Past Due	15,718	17,691
Current	6,767	7,476
Total loans	22,485	25,167
Nonaccrual Loan [Member] | Installment [Member]
Summarized details of Loans
30-59 Days Past Due	86	129
60-89 Days Past Due	200	24
90 Days or More Past Due	133	289
Total Past Due	419	442
Current	496	672
Total loans	915	1,114
Nonaccrual Loan [Member] | Residential, Prime, Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	3,817	3,199
60-89 Days Past Due	3,536	3,257
90 Days or More Past Due	24,194	26,201
Total Past Due	31,547	32,657
Current	17,358	14,975
Total loans	48,905	47,632
Nonaccrual Loan [Member] | Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	5,727	5,053
60-89 Days Past Due	5,952	4,916
90 Days or More Past Due	36,005	40,821
Total Past Due	47,684	50,790
Current	24,621	23,123
Total loans	$ 72,305	$ 73,913