Loans, Allowance for Loan Losses, and Credit Quality Loans by Past Due Status (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Summarized details of Loans
30-59 Days Past Due	$ 39,567	$ 43,388
60-89 Days Past Due	14,751	33,281
90 Days or More Past Due	62,373	86,863
Total Past Due	116,691	163,532
Current	17,042,399	15,732,729
Total loans	17,159,090	15,896,261
Percent of current nonaccrual loans	59.00%	42.00%
Commercial And Industrial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	4,096	4,388
60-89 Days Past Due	3,166	5,200
90 Days or More Past Due	7,902	10,964
Total Past Due	15,164	20,552
Current	5,588,735	4,802,128
Total loans	5,603,899	4,822,680
Commercial Real Estate Owner Occupied Portfolio [Member]
Summarized details of Loans
30-59 Days Past Due	1,453	3,497
60-89 Days Past Due	2,233	3,815
90 Days or More Past Due	10,159	11,125
Total Past Due	13,845	18,437
Current	1,000,490	1,096,278
Total loans	1,014,335	1,114,715
Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	0	0
60-89 Days Past Due	0	0
90 Days or More Past Due	550	69
Total Past Due	550	69
Current	52,050	55,414
Total loans	52,600	55,483
Commercial And Business Lending [Member]
Summarized details of Loans
30-59 Days Past Due	5,549	7,885
60-89 Days Past Due	5,399	9,015
90 Days or More Past Due	18,611	22,158
Total Past Due	29,559	39,058
Current	6,641,275	5,953,820
Total loans	6,670,834	5,992,878
Commercial Real Estate Investor Portfolio Segment [Member]
Summarized details of Loans
30-59 Days Past Due	16,009	12,489
60-89 Days Past Due	685	15,033
90 Days or More Past Due	8,418	20,466
Total Past Due	25,112	47,988
Current	3,018,249	2,891,468
Total loans	3,043,361	2,939,456
Commercial Real Estate Construction Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	363	3,212
60-89 Days Past Due	156	1,118
90 Days or More Past Due	1,061	2,267
Total Past Due	1,580	6,597
Current	980,846	889,651
Total loans	982,426	896,248
Commercial Real Estate Lending [Member]
Summarized details of Loans
30-59 Days Past Due	16,372	15,701
60-89 Days Past Due	841	16,151
90 Days or More Past Due	9,479	22,733
Total Past Due	26,692	54,585
Current	3,999,095	3,781,119
Total loans	4,025,787	3,835,704
Commercial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	21,921	23,586
60-89 Days Past Due	6,240	25,166
90 Days or More Past Due	28,090	44,891
Total Past Due	56,251	93,643
Current	10,640,370	9,734,939
Total loans	10,696,621	9,828,582
Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	9,605	10,336
60-89 Days Past Due	4,806	3,704
90 Days or More Past Due	10,607	14,677
Total Past Due	25,018	28,717
Current	1,651,507	1,796,297
Total loans	1,676,525	1,825,014
Installment and Credit Cards [Member]
Summarized details of Loans
30-59 Days Past Due	1,163	1,014
60-89 Days Past Due	761	289
90 Days or More Past Due	1,507	926
Total Past Due	3,431	2,229
Current	456,251	404,845
Total loans	459,682	407,074
Residential, Prime, Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	6,878	8,452
60-89 Days Past Due	2,944	4,122
90 Days or More Past Due	22,169	26,369
Total Past Due	31,991	38,943
Current	4,294,271	3,796,648
Total loans	4,326,262	3,835,591
Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	17,646	19,802
60-89 Days Past Due	8,511	8,115
90 Days or More Past Due	34,283	41,972
Total Past Due	60,440	69,889
Current	6,402,029	5,997,790
Total loans	6,462,469	6,067,679
Accruing Loans [Member]
Summarized details of Loans
30-59 Days Past Due	31,276	29,071
60-89 Days Past Due	7,401	23,978
90 Days or More Past Due	1,690	2,350
Total Past Due	40,367	55,399
Current	16,934,585	15,655,434
Total loans	16,974,952	15,710,833
Accruing Loans [Member] | Commercial And Industrial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	2,035	3,390
60-89 Days Past Due	1,912	3,436
90 Days or More Past Due	269	1,199
Total Past Due	4,216	8,025
Current	5,548,540	4,776,936
Total loans	5,552,756	4,784,961
Accruing Loans [Member] | Commercial Real Estate Owner Occupied Portfolio [Member]
Summarized details of Loans
30-59 Days Past Due	1,024	1,015
60-89 Days Past Due	1,651	2,091
90 Days or More Past Due	0	0
Total Past Due	2,675	3,106
Current	987,320	1,081,945
Total loans	989,995	1,085,051
Accruing Loans [Member] | Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	0	0
60-89 Days Past Due	0	0
90 Days or More Past Due	0	0
Total Past Due	0	0
Current	50,653	55,414
Total loans	50,653	55,414
Accruing Loans [Member] | Commercial And Business Lending [Member]
Summarized details of Loans
30-59 Days Past Due	3,059	4,405
60-89 Days Past Due	3,563	5,527
90 Days or More Past Due	269	1,199
Total Past Due	6,891	11,131
Current	6,586,513	5,914,295
Total loans	6,593,404	5,925,426
Accruing Loans [Member] | Commercial Real Estate Investor Portfolio Segment [Member]
Summarized details of Loans
30-59 Days Past Due	15,869	9,081
60-89 Days Past Due	0	14,134
90 Days or More Past Due	0	0
Total Past Due	15,869	23,215
Current	3,002,386	2,878,645
Total loans	3,018,255	2,901,860
Accruing Loans [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	299	836
60-89 Days Past Due	100	1,118
90 Days or More Past Due	0	0
Total Past Due	399	1,954
Current	973,840	887,827
Total loans	974,239	889,781
Accruing Loans [Member] | Commercial Real Estate Lending [Member]
Summarized details of Loans
30-59 Days Past Due	16,168	9,917
60-89 Days Past Due	100	15,252
90 Days or More Past Due	0	0
Total Past Due	16,268	25,169
Current	3,976,226	3,766,472
Total loans	3,992,494	3,791,641
Accruing Loans [Member] | Commercial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	19,227	14,322
60-89 Days Past Due	3,663	20,779
90 Days or More Past Due	269	1,199
Total Past Due	23,159	36,300
Current	10,562,739	9,680,767
Total loans	10,585,898	9,717,067
Accruing Loans [Member] | Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	7,999	8,611
60-89 Days Past Due	2,739	2,069
90 Days or More Past Due	0	346
Total Past Due	10,738	11,026
Current	1,644,526	1,788,821
Total loans	1,655,264	1,799,847
Accruing Loans [Member] | Installment and Credit Cards [Member]
Summarized details of Loans
30-59 Days Past Due	1,106	885
60-89 Days Past Due	712	265
90 Days or More Past Due	1,369	637
Total Past Due	3,187	1,787
Current	455,842	404,173
Total loans	459,029	405,960
Accruing Loans [Member] | Residential, Prime, Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	2,944	5,253
60-89 Days Past Due	287	865
90 Days or More Past Due	52	168
Total Past Due	3,283	6,286
Current	4,271,478	3,781,673
Total loans	4,274,761	3,787,959
Accruing Loans [Member] | Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	12,049	14,749
60-89 Days Past Due	3,738	3,199
90 Days or More Past Due	1,421	1,151
Total Past Due	17,208	19,099
Current	6,371,846	5,974,667
Total loans	6,389,054	5,993,766
Nonaccrual Loan [Member]
Summarized details of Loans
30-59 Days Past Due	8,291	14,317
60-89 Days Past Due	7,350	9,303
90 Days or More Past Due	60,683	84,513
Total Past Due	76,324	108,133
Current	107,814	77,295
Total loans	184,138	185,428
Nonaccrual Loan [Member] | Commercial And Industrial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	2,061	998
60-89 Days Past Due	1,254	1,764
90 Days or More Past Due	7,633	9,765
Total Past Due	10,948	12,527
Current	40,195	25,192
Total loans	51,143	37,719
Nonaccrual Loan [Member] | Commercial Real Estate Owner Occupied Portfolio [Member]
Summarized details of Loans
30-59 Days Past Due	429	2,482
60-89 Days Past Due	582	1,724
90 Days or More Past Due	10,159	11,125
Total Past Due	11,170	15,331
Current	13,170	14,333
Total loans	24,340	29,664
Nonaccrual Loan [Member] | Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	0	0
60-89 Days Past Due	0	0
90 Days or More Past Due	550	69
Total Past Due	550	69
Current	1,397	0
Total loans	1,947	69
Nonaccrual Loan [Member] | Commercial And Business Lending [Member]
Summarized details of Loans
30-59 Days Past Due	2,490	3,480
60-89 Days Past Due	1,836	3,488
90 Days or More Past Due	18,342	20,959
Total Past Due	22,668	27,927
Current	54,762	39,525
Total loans	77,430	67,452
Nonaccrual Loan [Member] | Commercial Real Estate Investor Portfolio Segment [Member]
Summarized details of Loans
30-59 Days Past Due	140	3,408
60-89 Days Past Due	685	899
90 Days or More Past Due	8,418	20,466
Total Past Due	9,243	24,773
Current	15,863	12,823
Total loans	25,106	37,596
Nonaccrual Loan [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	64	2,376
60-89 Days Past Due	56	0
90 Days or More Past Due	1,061	2,267
Total Past Due	1,181	4,643
Current	7,006	1,824
Total loans	8,187	6,467
Nonaccrual Loan [Member] | Commercial Real Estate Lending [Member]
Summarized details of Loans
30-59 Days Past Due	204	5,784
60-89 Days Past Due	741	899
90 Days or More Past Due	9,479	22,733
Total Past Due	10,424	29,416
Current	22,869	14,647
Total loans	33,293	44,063
Nonaccrual Loan [Member] | Commercial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	2,694	9,264
60-89 Days Past Due	2,577	4,387
90 Days or More Past Due	27,821	43,692
Total Past Due	33,092	57,343
Current	77,631	54,172
Total loans	110,723	111,515
Nonaccrual Loan [Member] | Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	1,606	1,725
60-89 Days Past Due	2,067	1,635
90 Days or More Past Due	10,607	14,331
Total Past Due	14,280	17,691
Current	6,981	7,476
Total loans	21,261	25,167
Nonaccrual Loan [Member] | Installment and Credit Cards [Member]
Summarized details of Loans
30-59 Days Past Due	57	129
60-89 Days Past Due	49	24
90 Days or More Past Due	138	289
Total Past Due	244	442
Current	409	672
Total loans	653	1,114
Nonaccrual Loan [Member] | Residential, Prime, Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	3,934	3,199
60-89 Days Past Due	2,657	3,257
90 Days or More Past Due	22,117	26,201
Total Past Due	28,708	32,657
Current	22,793	14,975
Total loans	51,501	47,632
Nonaccrual Loan [Member] | Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	5,597	5,053
60-89 Days Past Due	4,773	4,916
90 Days or More Past Due	32,862	40,821
Total Past Due	43,232	50,790
Current	30,183	23,123
Total loans	$ 73,415	$ 73,913