Loans, Allowance for Loan Losses, and Credit Quality (Details 6) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Summarized details of Loans
30-59 Days Past Due	$ 45,101	$ 46,612
60-89 Days Past Due	26,552	29,844
90 Days or More Past Due	155,996	175,181
Total Past Due	227,649	251,637
Current	14,471,253	13,779,434
Total loans	14,698,902	14,031,071
Commercial and industrial financing receivable [Member]
Summarized details of Loans
30-59 Days Past Due	4,674	8,887
60-89 Days Past Due	1,697	12,163
90 Days or More Past Due	16,728	24,547
Total Past Due	23,099	45,597
Current	4,053,271	3,679,139
Total loans	4,076,370	3,724,736
Commercial Real Estate Owner Occupied Portfolio Segment
Summarized details of Loans
30-59 Days Past Due	6,358	8,978
60-89 Days Past Due	1,050	489
90 Days or More Past Due	15,983	19,724
Total Past Due	23,391	29,191
Current	1,093,424	1,057,638
Total loans	1,116,815	1,086,829
Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	28	31
60-89 Days Past Due	11	73
90 Days or More Past Due	837	858
Total Past Due	876	962
Current	61,874	57,232
Total loans	62,750	58,194
Commercial and business lending
Summarized details of Loans
30-59 Days Past Due	11,060	17,896
60-89 Days Past Due	2,758	12,725
90 Days or More Past Due	33,548	45,129
Total Past Due	47,366	75,750
Current	5,208,569	4,794,009
Total loans	5,255,935	4,869,759
Commercial Real Estate Investor Portfolio Segment
Summarized details of Loans
30-59 Days Past Due	8,496	5,102
60-89 Days Past Due	10,303	4,930
90 Days or More Past Due	30,143	31,529
Total Past Due	48,942	41,561
Current	2,761,579	2,522,206
Total loans	2,810,521	2,563,767
Real estate construction
Summarized details of Loans
30-59 Days Past Due	763	909
60-89 Days Past Due	2,402	605
90 Days or More Past Due	15,368	19,106
Total Past Due	18,533	20,620
Current	594,023	563,426
Total loans	612,556	584,046
Commercial real estate lending
Summarized details of Loans
30-59 Days Past Due	9,259	6,011
60-89 Days Past Due	12,705	5,535
90 Days or More Past Due	45,511	50,635
Total Past Due	67,475	62,181
Current	3,355,602	3,085,632
Total loans	3,423,077	3,147,813
Total commercial [Member]
Summarized details of Loans
30-59 Days Past Due	20,319	23,907
60-89 Days Past Due	15,463	18,260
90 Days or More Past Due	79,059	95,764
Total Past Due	114,841	137,931
Current	8,564,171	7,879,641
Total loans	8,679,012	8,017,572
Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	12,394	12,217
60-89 Days Past Due	7,566	5,198
90 Days or More Past Due	30,532	34,976
Total Past Due	50,492	52,391
Current	2,379,102	2,452,313
Total loans	2,429,594	2,504,704
Installment
Summarized details of Loans
30-59 Days Past Due	1,168	2,187
60-89 Days Past Due	714	1,181
90 Days or More Past Due	2,308	1,288
Total Past Due	4,190	4,656
Current	506,641	553,126
Total loans	510,831	557,782
Total retail [Member]
Summarized details of Loans
30-59 Days Past Due	13,562	14,404
60-89 Days Past Due	8,280	6,379
90 Days or More Past Due	32,840	36,264
Total Past Due	54,682	57,047
Current	2,885,743	3,005,439
Total loans	2,940,425	3,062,486
Residential mortgage [Member]
Summarized details of Loans
30-59 Days Past Due	11,220	8,301
60-89 Days Past Due	2,809	5,205
90 Days or More Past Due	44,097	43,153
Total Past Due	58,126	56,659
Current	3,021,339	2,894,354
Total loans	3,079,465	2,951,013
Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	24,782	22,705
60-89 Days Past Due	11,089	11,584
90 Days or More Past Due	76,937	79,417
Total Past Due	112,808	113,706
Current	5,907,082	5,899,793
Total loans	6,019,890	6,013,499
Accruing Loans [Member]
Summarized details of Loans
30-59 Days Past Due	32,416	31,478
60-89 Days Past Due	15,381	12,432
90 Days or More Past Due	5,224	4,925
Total Past Due	53,021	48,835
Current	14,328,009	13,625,464
Total loans	14,381,030	13,674,299
Accruing Loans [Member] | Commercial and industrial financing receivable [Member]
Summarized details of Loans
30-59 Days Past Due	3,698	3,513
60-89 Days Past Due	767	5,230
90 Days or More Past Due	0	3,755
Total Past Due	4,465	12,498
Current	4,025,794	3,656,163
Total loans	4,030,259	3,668,661
Accruing Loans [Member] | Commercial Real Estate Owner Occupied Portfolio Segment
Summarized details of Loans
30-59 Days Past Due	1,632	6,788
60-89 Days Past Due	493	304
90 Days or More Past Due	0	0
Total Past Due	2,125	7,092
Current	1,081,273	1,044,019
Total loans	1,083,398	1,051,111
Accruing Loans [Member] | Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	28	31
60-89 Days Past Due	11	73
90 Days or More Past Due	0	0
Total Past Due	39	104
Current	54,451	47,446
Total loans	54,490	47,550
Accruing Loans [Member] | Commercial and business lending
Summarized details of Loans
30-59 Days Past Due	5,358	10,332
60-89 Days Past Due	1,271	5,607
90 Days or More Past Due	0	3,755
Total Past Due	6,629	19,694
Current	5,161,518	4,747,628
Total loans	5,168,147	4,767,322
Accruing Loans [Member] | Commercial Real Estate Investor Portfolio Segment
Summarized details of Loans
30-59 Days Past Due	5,293	2,770
60-89 Days Past Due	7,561	2,200
90 Days or More Past Due	4,563	0
Total Past Due	17,417	4,970
Current	2,704,298	2,459,445
Total loans	2,721,715	2,464,415
Accruing Loans [Member] | Real estate construction
Summarized details of Loans
30-59 Days Past Due	763	873
60-89 Days Past Due	855	123
90 Days or More Past Due	0	481
Total Past Due	1,618	1,477
Current	574,535	540,763
Total loans	576,153	542,240
Accruing Loans [Member] | Commercial real estate lending
Summarized details of Loans
30-59 Days Past Due	6,056	3,643
60-89 Days Past Due	8,416	2,323
90 Days or More Past Due	4,563	481
Total Past Due	19,035	6,447
Current	3,278,833	3,000,208
Total loans	3,297,868	3,006,655
Accruing Loans [Member] | Total commercial [Member]
Summarized details of Loans
30-59 Days Past Due	11,414	13,975
60-89 Days Past Due	9,687	7,930
90 Days or More Past Due	4,563	4,236
Total Past Due	25,664	26,141
Current	8,440,351	7,747,836
Total loans	8,466,015	7,773,977
Accruing Loans [Member] | Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	10,859	9,399
60-89 Days Past Due	4,443	2,790
90 Days or More Past Due	0	0
Total Past Due	15,302	12,189
Current	2,372,756	2,445,608
Total loans	2,388,058	2,457,797
Accruing Loans [Member] | Installment
Summarized details of Loans
30-59 Days Past Due	1,074	1,784
60-89 Days Past Due	484	808
90 Days or More Past Due	661	689
Total Past Due	2,219	3,281
Current	505,565	551,786
Total loans	507,784	555,067
Accruing Loans [Member] | Total retail [Member]
Summarized details of Loans
30-59 Days Past Due	11,933	11,183
60-89 Days Past Due	4,927	3,598
90 Days or More Past Due	661	689
Total Past Due	17,521	15,470
Current	2,878,321	2,997,394
Total loans	2,895,842	3,012,864
Accruing Loans [Member] | Residential mortgage [Member]
Summarized details of Loans
30-59 Days Past Due	9,069	6,320
60-89 Days Past Due	767	904
90 Days or More Past Due	0	0
Total Past Due	9,836	7,224
Current	3,009,337	2,880,234
Total loans	3,019,173	2,887,458
Accruing Loans [Member] | Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	21,002	17,503
60-89 Days Past Due	5,694	4,502
90 Days or More Past Due	661	689
Total Past Due	27,357	22,694
Current	5,887,658	5,877,628
Total loans	5,915,015	5,900,322
Nonaccrual Loans [Member]
Summarized details of Loans
30-59 Days Past Due	12,685	15,134
60-89 Days Past Due	11,171	17,412
90 Days or More Past Due	150,772	170,256
Total Past Due	174,628	202,802
Current	143,244	153,970
Total loans	317,872	356,772
Nonaccrual Loans [Member] | Commercial and industrial financing receivable [Member]
Summarized details of Loans
30-59 Days Past Due	976	5,374
60-89 Days Past Due	930	6,933
90 Days or More Past Due	16,728	20,792
Total Past Due	18,634	33,099
Current	27,477	22,976
Total loans	46,111	56,075
Nonaccrual Loans [Member] | Commercial Real Estate Owner Occupied Portfolio Segment
Summarized details of Loans
30-59 Days Past Due	4,726	2,190
60-89 Days Past Due	557	185
90 Days or More Past Due	15,983	19,724
Total Past Due	21,266	22,099
Current	12,151	13,619
Total loans	33,417	35,718
Nonaccrual 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	837	858
Total Past Due	837	858
Current	7,423	9,786
Total loans	8,260	10,644
Nonaccrual Loans [Member] | Commercial and business lending
Summarized details of Loans
30-59 Days Past Due	5,702	7,564
60-89 Days Past Due	1,487	7,118
90 Days or More Past Due	33,548	41,374
Total Past Due	40,737	56,056
Current	47,051	46,381
Total loans	87,788	102,437
Nonaccrual Loans [Member] | Commercial Real Estate Investor Portfolio Segment
Summarized details of Loans
30-59 Days Past Due	3,203	2,332
60-89 Days Past Due	2,742	2,730
90 Days or More Past Due	25,580	31,529
Total Past Due	31,525	36,591
Current	57,281	62,761
Total loans	88,806	99,352
Nonaccrual Loans [Member] | Real estate construction
Summarized details of Loans
30-59 Days Past Due	0	36
60-89 Days Past Due	1,547	482
90 Days or More Past Due	15,368	18,625
Total Past Due	16,915	19,143
Current	19,488	22,663
Total loans	36,403	41,806
Nonaccrual Loans [Member] | Commercial real estate lending
Summarized details of Loans
30-59 Days Past Due	3,203	2,368
60-89 Days Past Due	4,289	3,212
90 Days or More Past Due	40,948	50,154
Total Past Due	48,440	55,734
Current	76,769	85,424
Total loans	125,209	141,158
Nonaccrual Loans [Member] | Total commercial [Member]
Summarized details of Loans
30-59 Days Past Due	8,905	9,932
60-89 Days Past Due	5,776	10,330
90 Days or More Past Due	74,496	91,528
Total Past Due	89,177	111,790
Current	123,820	131,805
Total loans	212,997	243,595
Nonaccrual Loans [Member] | Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	1,535	2,818
60-89 Days Past Due	3,123	2,408
90 Days or More Past Due	30,532	34,976
Total Past Due	35,190	40,202
Current	6,346	6,705
Total loans	41,536	46,907
Nonaccrual Loans [Member] | Installment
Summarized details of Loans
30-59 Days Past Due	94	403
60-89 Days Past Due	230	373
90 Days or More Past Due	1,647	599
Total Past Due	1,971	1,375
Current	1,076	1,340
Total loans	3,047	2,715
Nonaccrual Loans [Member] | Total retail [Member]
Summarized details of Loans
30-59 Days Past Due	1,629	3,221
60-89 Days Past Due	3,353	2,781
90 Days or More Past Due	32,179	35,575
Total Past Due	37,161	41,577
Current	7,422	8,045
Total loans	44,583	49,622
Nonaccrual Loans [Member] | Residential mortgage [Member]
Summarized details of Loans
30-59 Days Past Due	2,151	1,981
60-89 Days Past Due	2,042	4,301
90 Days or More Past Due	44,097	43,153
Total Past Due	48,290	49,435
Current	12,002	14,120
Total loans	60,292	63,555
Nonaccrual Loans [Member] | Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	3,780	5,202
60-89 Days Past Due	5,395	7,082
90 Days or More Past Due	76,276	78,728
Total Past Due	85,451	91,012
Current	19,424	22,165
Total loans	$ 104,875	$ 113,177