Loans, Allowance for Loan Losses, and Credit Quality (Details 6) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Summarized details of Loans
30-59 Days Past Due	$ 40,999	$ 46,612
60-89 Days Past Due	27,864	29,844
90 Days or More Past Due	147,170	175,181
Total Past Due	216,033	251,637
Current	14,750,181	13,779,434
Total loans	14,966,214	14,031,071
Commercial And Industrial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	3,448	8,887
60-89 Days Past Due	5,283	12,163
90 Days or More Past Due	10,808	24,547
Total Past Due	19,539	45,597
Current	4,245,817	3,679,139
Total loans	4,265,356	3,724,736
Commercial Real Estate Owner Occupied Portfolio [Member]
Summarized details of Loans
30-59 Days Past Due	3,250	8,978
60-89 Days Past Due	4,966	489
90 Days or More Past Due	12,919	19,724
Total Past Due	21,135	29,191
Current	1,176,382	1,057,638
Total loans	1,197,517	1,086,829
Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	0	31
60-89 Days Past Due	17	73
90 Days or More Past Due	483	858
Total Past Due	500	962
Current	60,318	57,232
Total loans	60,818	58,194
Commercial And Business Lending [Member]
Summarized details of Loans
30-59 Days Past Due	6,698	17,896
60-89 Days Past Due	10,266	12,725
90 Days or More Past Due	24,210	45,129
Total Past Due	41,174	75,750
Current	5,482,517	4,794,009
Total loans	5,523,691	4,869,759
Commercial Real Estate Investor Portfolio Segment [Member]
Summarized details of Loans
30-59 Days Past Due	10,541	5,102
60-89 Days Past Due	5,710	4,930
90 Days or More Past Due	33,660	31,529
Total Past Due	49,911	41,561
Current	2,737,247	2,522,206
Total loans	2,787,158	2,563,767
Commercial Real Estate Construction Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	1,057	909
60-89 Days Past Due	485	605
90 Days or More Past Due	16,578	19,106
Total Past Due	18,120	20,620
Current	593,066	563,426
Total loans	611,186	584,046
Commercial Real Estate Lending [Member]
Summarized details of Loans
30-59 Days Past Due	11,598	6,011
60-89 Days Past Due	6,195	5,535
90 Days or More Past Due	50,238	50,635
Total Past Due	68,031	62,181
Current	3,330,313	3,085,632
Total loans	3,398,344	3,147,813
Commercial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	18,296	23,907
60-89 Days Past Due	16,461	18,260
90 Days or More Past Due	74,448	95,764
Total Past Due	109,205	137,931
Current	8,812,830	7,879,641
Total loans	8,922,035	8,017,572
Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	13,092	12,217
60-89 Days Past Due	5,871	5,198
90 Days or More Past Due	29,347	34,976
Total Past Due	48,310	52,391
Current	2,308,590	2,452,313
Total loans	2,356,900	2,504,704
Installment [Member]
Summarized details of Loans
30-59 Days Past Due	1,379	2,187
60-89 Days Past Due	631	1,181
90 Days or More Past Due	2,202	1,288
Total Past Due	4,212	4,656
Current	478,239	553,126
Total loans	482,451	557,782
Consumer Retail Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	14,471	14,404
60-89 Days Past Due	6,502	6,379
90 Days or More Past Due	31,549	36,264
Total Past Due	52,522	57,047
Current	2,786,829	3,005,439
Total loans	2,839,351	3,062,486
Residential, Prime, Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	8,232	8,301
60-89 Days Past Due	4,901	5,205
90 Days or More Past Due	41,173	43,153
Total Past Due	54,306	56,659
Current	3,150,522	2,894,354
Total loans	3,204,828	2,951,013
Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	22,703	22,705
60-89 Days Past Due	11,403	11,584
90 Days or More Past Due	72,722	79,417
Total Past Due	106,828	113,706
Current	5,937,351	5,899,793
Total loans	6,044,179	6,013,499
Accruing Loans [Member]
Summarized details of Loans
30-59 Days Past Due	30,707	31,478
60-89 Days Past Due	11,405	12,432
90 Days or More Past Due	2,334	4,925
Total Past Due	44,446	48,835
Current	14,643,596	13,625,464
Total loans	14,688,042	13,674,299
Accruing Loans [Member] | Commercial And Industrial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	2,525	3,513
60-89 Days Past Due	1,270	5,230
90 Days or More Past Due	0	3,755
Total Past Due	3,795	12,498
Current	4,219,867	3,656,163
Total loans	4,223,662	3,668,661
Accruing Loans [Member] | Commercial Real Estate Owner Occupied Portfolio [Member]
Summarized details of Loans
30-59 Days Past Due	1,453	6,788
60-89 Days Past Due	3,390	304
90 Days or More Past Due	1,052	0
Total Past Due	5,895	7,092
Current	1,164,461	1,044,019
Total loans	1,170,356	1,051,111
Accruing Loans [Member] | Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	0	31
60-89 Days Past Due	17	73
90 Days or More Past Due	0	0
Total Past Due	17	104
Current	54,874	47,446
Total loans	54,891	47,550
Accruing Loans [Member] | Commercial And Business Lending [Member]
Summarized details of Loans
30-59 Days Past Due	3,978	10,332
60-89 Days Past Due	4,677	5,607
90 Days or More Past Due	1,052	3,755
Total Past Due	9,707	19,694
Current	5,439,202	4,747,628
Total loans	5,448,909	4,767,322
Accruing Loans [Member] | Commercial Real Estate Investor Portfolio Segment [Member]
Summarized details of Loans
30-59 Days Past Due	7,203	2,770
60-89 Days Past Due	1,606	2,200
90 Days or More Past Due	615	0
Total Past Due	9,424	4,970
Current	2,706,212	2,459,445
Total loans	2,715,636	2,464,415
Accruing Loans [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	1,057	873
60-89 Days Past Due	197	123
90 Days or More Past Due	0	481
Total Past Due	1,254	1,477
Current	578,248	540,763
Total loans	579,502	542,240
Accruing Loans [Member] | Commercial Real Estate Lending [Member]
Summarized details of Loans
30-59 Days Past Due	8,260	3,643
60-89 Days Past Due	1,803	2,323
90 Days or More Past Due	615	481
Total Past Due	10,678	6,447
Current	3,284,460	3,000,208
Total loans	3,295,138	3,006,655
Accruing Loans [Member] | Commercial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	12,238	13,975
60-89 Days Past Due	6,480	7,930
90 Days or More Past Due	1,667	4,236
Total Past Due	20,385	26,141
Current	8,723,662	7,747,836
Total loans	8,744,047	7,773,977
Accruing Loans [Member] | Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	11,020	9,399
60-89 Days Past Due	3,803	2,790
90 Days or More Past Due	55	0
Total Past Due	14,878	12,189
Current	2,303,555	2,445,608
Total loans	2,318,433	2,457,797
Accruing Loans [Member] | Installment [Member]
Summarized details of Loans
30-59 Days Past Due	1,235	1,784
60-89 Days Past Due	458	808
90 Days or More Past Due	612	689
Total Past Due	2,305	3,281
Current	477,253	551,786
Total loans	479,558	555,067
Accruing Loans [Member] | Consumer Retail Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	12,255	11,183
60-89 Days Past Due	4,261	3,598
90 Days or More Past Due	667	689
Total Past Due	17,183	15,470
Current	2,780,808	2,997,394
Total loans	2,797,991	3,012,864
Accruing Loans [Member] | Residential, Prime, Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	6,214	6,320
60-89 Days Past Due	664	904
90 Days or More Past Due	0	0
Total Past Due	6,878	7,224
Current	3,139,126	2,880,234
Total loans	3,146,004	2,887,458
Accruing Loans [Member] | Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	18,469	17,503
60-89 Days Past Due	4,925	4,502
90 Days or More Past Due	667	689
Total Past Due	24,061	22,694
Current	5,919,934	5,877,628
Total loans	5,943,995	5,900,322
Nonaccrual Loan [Member]
Summarized details of Loans
30-59 Days Past Due	10,292	15,134
60-89 Days Past Due	16,459	17,412
90 Days or More Past Due	144,836	170,256
Total Past Due	171,587	202,802
Current	106,585	153,970
Total loans	278,172	356,772
Nonaccrual Loan [Member] | Commercial And Industrial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	923	5,374
60-89 Days Past Due	4,013	6,933
90 Days or More Past Due	10,808	20,792
Total Past Due	15,744	33,099
Current	25,950	22,976
Total loans	41,694	56,075
Nonaccrual Loan [Member] | Commercial Real Estate Owner Occupied Portfolio [Member]
Summarized details of Loans
30-59 Days Past Due	1,797	2,190
60-89 Days Past Due	1,576	185
90 Days or More Past Due	11,867	19,724
Total Past Due	15,240	22,099
Current	11,921	13,619
Total loans	27,161	35,718
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	483	858
Total Past Due	483	858
Current	5,444	9,786
Total loans	5,927	10,644
Nonaccrual Loan [Member] | Commercial And Business Lending [Member]
Summarized details of Loans
30-59 Days Past Due	2,720	7,564
60-89 Days Past Due	5,589	7,118
90 Days or More Past Due	23,158	41,374
Total Past Due	31,467	56,056
Current	43,315	46,381
Total loans	74,782	102,437
Nonaccrual Loan [Member] | Commercial Real Estate Investor Portfolio Segment [Member]
Summarized details of Loans
30-59 Days Past Due	3,338	2,332
60-89 Days Past Due	4,104	2,730
90 Days or More Past Due	33,045	31,529
Total Past Due	40,487	36,591
Current	31,035	62,761
Total loans	71,522	99,352
Nonaccrual Loan [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	0	36
60-89 Days Past Due	288	482
90 Days or More Past Due	16,578	18,625
Total Past Due	16,866	19,143
Current	14,818	22,663
Total loans	31,684	41,806
Nonaccrual Loan [Member] | Commercial Real Estate Lending [Member]
Summarized details of Loans
30-59 Days Past Due	3,338	2,368
60-89 Days Past Due	4,392	3,212
90 Days or More Past Due	49,623	50,154
Total Past Due	57,353	55,734
Current	45,853	85,424
Total loans	103,206	141,158
Nonaccrual Loan [Member] | Commercial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	6,058	9,932
60-89 Days Past Due	9,981	10,330
90 Days or More Past Due	72,781	91,528
Total Past Due	88,820	111,790
Current	89,168	131,805
Total loans	177,988	243,595
Nonaccrual Loan [Member] | Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	2,072	2,818
60-89 Days Past Due	2,068	2,408
90 Days or More Past Due	29,292	34,976
Total Past Due	33,432	40,202
Current	5,035	6,705
Total loans	38,467	46,907
Nonaccrual Loan [Member] | Installment [Member]
Summarized details of Loans
30-59 Days Past Due	144	403
60-89 Days Past Due	173	373
90 Days or More Past Due	1,590	599
Total Past Due	1,907	1,375
Current	986	1,340
Total loans	2,893	2,715
Nonaccrual Loan [Member] | Consumer Retail Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	2,216	3,221
60-89 Days Past Due	2,241	2,781
90 Days or More Past Due	30,882	35,575
Total Past Due	35,339	41,577
Current	6,021	8,045
Total loans	41,360	49,622
Nonaccrual Loan [Member] | Residential, Prime, Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	2,018	1,981
60-89 Days Past Due	4,237	4,301
90 Days or More Past Due	41,173	43,153
Total Past Due	47,428	49,435
Current	11,396	14,120
Total loans	58,824	63,555
Nonaccrual Loan [Member] | Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	4,234	5,202
60-89 Days Past Due	6,478	7,082
90 Days or More Past Due	72,055	78,728
Total Past Due	82,767	91,012
Current	17,417	22,165
Total loans	$ 100,184	$ 113,177