Loans, Allowance for Loan Losses, and Credit Quality Loans by Past Due Status (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Summarized details of Loans
30-59 Days Past Due	$ 63,892	$ 63,973
60-89 Days Past Due	19,854	26,720
90 Days or More Past Due	105,738	134,445
Total Past Due	189,484	225,138
Current	15,396,370	15,185,884
Total loans	15,585,854	15,411,022
Commercial And Industrial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	3,837	18,116
60-89 Days Past Due	5,701	2,573
90 Days or More Past Due	12,264	12,041
Total Past Due	21,802	32,730
Current	4,681,254	4,469,291
Total loans	4,703,056	4,502,021
Commercial Real Estate Owner Occupied Portfolio [Member]
Summarized details of Loans
30-59 Days Past Due	6,746	11,909
60-89 Days Past Due	4,236	2,382
90 Days or More Past Due	11,755	12,127
Total Past Due	22,737	26,418
Current	1,124,615	1,193,329
Total loans	1,147,352	1,219,747
Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	1,000	15
60-89 Days Past Due	0	12
90 Days or More Past Due	99	9
Total Past Due	1,099	36
Current	50,628	64,160
Total loans	51,727	64,196
Commercial And Business Lending [Member]
Summarized details of Loans
30-59 Days Past Due	11,583	30,040
60-89 Days Past Due	9,937	4,967
90 Days or More Past Due	24,118	24,177
Total Past Due	45,638	59,184
Current	5,856,497	5,726,780
Total loans	5,902,135	5,785,964
Commercial Real Estate Investor Portfolio Segment [Member]
Summarized details of Loans
30-59 Days Past Due	24,238	8,621
60-89 Days Past Due	231	8,120
90 Days or More Past Due	36,503	31,294
Total Past Due	60,972	48,035
Current	2,786,180	2,858,724
Total loans	2,847,152	2,906,759
Commercial Real Estate Construction Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	9,623	1,644
60-89 Days Past Due	297	1,527
90 Days or More Past Due	2,850	9,922
Total Past Due	12,770	13,093
Current	821,974	642,288
Total loans	834,744	655,381
Commercial Real Estate Lending [Member]
Summarized details of Loans
30-59 Days Past Due	33,861	10,265
60-89 Days Past Due	528	9,647
90 Days or More Past Due	39,353	41,216
Total Past Due	73,742	61,128
Current	3,608,154	3,501,012
Total loans	3,681,896	3,562,140
Commercial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	45,444	40,305
60-89 Days Past Due	10,465	14,614
90 Days or More Past Due	63,471	65,393
Total Past Due	119,380	120,312
Current	9,464,651	9,227,792
Total loans	9,584,031	9,348,104
Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	8,758	11,607
60-89 Days Past Due	4,707	5,905
90 Days or More Past Due	14,020	28,570
Total Past Due	27,485	46,082
Current	1,863,893	2,173,412
Total loans	1,891,378	2,219,494
Installment [Member]
Summarized details of Loans
30-59 Days Past Due	1,013	1,453
60-89 Days Past Due	457	950
90 Days or More Past Due	1,014	1,599
Total Past Due	2,484	4,002
Current	417,784	462,725
Total loans	420,268	466,727
Residential, Prime, Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	8,677	10,608
60-89 Days Past Due	4,225	5,251
90 Days or More Past Due	27,233	38,883
Total Past Due	40,135	54,742
Current	3,650,042	3,321,955
Total loans	3,690,177	3,376,697
Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	18,448	23,668
60-89 Days Past Due	9,389	12,106
90 Days or More Past Due	42,267	69,052
Total Past Due	70,104	104,826
Current	5,931,719	5,958,092
Total loans	6,001,823	6,062,918
Accruing Loans [Member]
Summarized details of Loans
30-59 Days Past Due	45,749	49,953
60-89 Days Past Due	10,633	14,128
90 Days or More Past Due	2,063	2,289
Total Past Due	58,445	66,370
Current	15,319,815	15,091,784
Total loans	15,378,260	15,158,154
Accruing Loans [Member] | Commercial And Industrial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	3,327	9,557
60-89 Days Past Due	3,191	1,782
90 Days or More Past Due	0	79
Total Past Due	6,518	11,418
Current	4,660,433	4,451,421
Total loans	4,666,951	4,462,839
Accruing Loans [Member] | Commercial Real Estate Owner Occupied Portfolio [Member]
Summarized details of Loans
30-59 Days Past Due	5,231	10,420
60-89 Days Past Due	3,274	633
90 Days or More Past Due	727	308
Total Past Due	9,232	11,361
Current	1,109,819	1,184,132
Total loans	1,119,051	1,195,493
Accruing Loans [Member] | Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	1,000	0
60-89 Days Past Due	0	12
90 Days or More Past Due	0	0
Total Past Due	1,000	12
Current	50,628	61,153
Total loans	51,628	61,165
Accruing Loans [Member] | Commercial And Business Lending [Member]
Summarized details of Loans
30-59 Days Past Due	9,558	19,977
60-89 Days Past Due	6,465	2,427
90 Days or More Past Due	727	387
Total Past Due	16,750	22,791
Current	5,820,880	5,696,706
Total loans	5,837,630	5,719,497
Accruing Loans [Member] | Commercial Real Estate Investor Portfolio Segment [Member]
Summarized details of Loans
30-59 Days Past Due	21,667	8,424
60-89 Days Past Due	80	5,048
90 Days or More Past Due	0	366
Total Past Due	21,747	13,838
Current	2,775,564	2,834,234
Total loans	2,797,311	2,848,072
Accruing Loans [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	617	1,628
60-89 Days Past Due	203	1,527
90 Days or More Past Due	471	283
Total Past Due	1,291	3,438
Current	814,783	624,641
Total loans	816,074	628,079
Accruing Loans [Member] | Commercial Real Estate Lending [Member]
Summarized details of Loans
30-59 Days Past Due	22,284	10,052
60-89 Days Past Due	283	6,575
90 Days or More Past Due	471	649
Total Past Due	23,038	17,276
Current	3,590,347	3,458,875
Total loans	3,613,385	3,476,151
Accruing Loans [Member] | Commercial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	31,842	30,029
60-89 Days Past Due	6,748	9,002
90 Days or More Past Due	1,198	1,036
Total Past Due	39,788	40,067
Current	9,411,227	9,155,581
Total loans	9,451,015	9,195,648
Accruing Loans [Member] | Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	7,170	10,151
60-89 Days Past Due	2,730	3,387
90 Days or More Past Due	32	96
Total Past Due	9,932	13,634
Current	1,856,003	2,166,645
Total loans	1,865,935	2,180,279
Accruing Loans [Member] | Installment [Member]
Summarized details of Loans
30-59 Days Past Due	831	1,300
60-89 Days Past Due	339	809
90 Days or More Past Due	723	1,013
Total Past Due	1,893	3,122
Current	417,106	461,767
Total loans	418,999	464,889
Accruing Loans [Member] | Residential, Prime, Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	5,906	8,473
60-89 Days Past Due	816	930
90 Days or More Past Due	110	144
Total Past Due	6,832	9,547
Current	3,635,479	3,307,791
Total loans	3,642,311	3,317,338
Accruing Loans [Member] | Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	13,907	19,924
60-89 Days Past Due	3,885	5,126
90 Days or More Past Due	865	1,253
Total Past Due	18,657	26,303
Current	5,908,588	5,936,203
Total loans	5,927,245	5,962,506
Nonaccrual Loan [Member]
Summarized details of Loans
30-59 Days Past Due	18,143	14,020
60-89 Days Past Due	9,221	12,592
90 Days or More Past Due	103,675	132,156
Total Past Due	131,039	158,768
Current	76,555	94,100
Total loans	207,594	252,868
Nonaccrual Loan [Member] | Commercial And Industrial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	510	8,559
60-89 Days Past Due	2,510	791
90 Days or More Past Due	12,264	11,962
Total Past Due	15,284	21,312
Current	20,821	17,870
Total loans	36,105	39,182
Nonaccrual Loan [Member] | Commercial Real Estate Owner Occupied Portfolio [Member]
Summarized details of Loans
30-59 Days Past Due	1,515	1,489
60-89 Days Past Due	962	1,749
90 Days or More Past Due	11,028	11,819
Total Past Due	13,505	15,057
Current	14,796	9,197
Total loans	28,301	24,254
Nonaccrual Loan [Member] | Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	0	15
60-89 Days Past Due	0	0
90 Days or More Past Due	99	9
Total Past Due	99	24
Current	0	3,007
Total loans	99	3,031
Nonaccrual Loan [Member] | Commercial And Business Lending [Member]
Summarized details of Loans
30-59 Days Past Due	2,025	10,063
60-89 Days Past Due	3,472	2,540
90 Days or More Past Due	23,391	23,790
Total Past Due	28,888	36,393
Current	35,617	30,074
Total loans	64,505	66,467
Nonaccrual Loan [Member] | Commercial Real Estate Investor Portfolio Segment [Member]
Summarized details of Loans
30-59 Days Past Due	2,571	197
60-89 Days Past Due	151	3,072
90 Days or More Past Due	36,503	30,928
Total Past Due	39,225	34,197
Current	10,616	24,490
Total loans	49,841	58,687
Nonaccrual Loan [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	9,006	16
60-89 Days Past Due	94	0
90 Days or More Past Due	2,379	9,639
Total Past Due	11,479	9,655
Current	7,191	17,647
Total loans	18,670	27,302
Nonaccrual Loan [Member] | Commercial Real Estate Lending [Member]
Summarized details of Loans
30-59 Days Past Due	11,577	213
60-89 Days Past Due	245	3,072
90 Days or More Past Due	38,882	40,567
Total Past Due	50,704	43,852
Current	17,807	42,137
Total loans	68,511	85,989
Nonaccrual Loan [Member] | Commercial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	13,602	10,276
60-89 Days Past Due	3,717	5,612
90 Days or More Past Due	62,273	64,357
Total Past Due	79,592	80,245
Current	53,424	72,211
Total loans	133,016	152,456
Nonaccrual Loan [Member] | Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	1,588	1,456
60-89 Days Past Due	1,977	2,518
90 Days or More Past Due	13,988	28,474
Total Past Due	17,553	32,448
Current	7,890	6,767
Total loans	25,443	39,215
Nonaccrual Loan [Member] | Installment [Member]
Summarized details of Loans
30-59 Days Past Due	182	153
60-89 Days Past Due	118	141
90 Days or More Past Due	291	586
Total Past Due	591	880
Current	678	958
Total loans	1,269	1,838
Nonaccrual Loan [Member] | Residential, Prime, Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	2,771	2,135
60-89 Days Past Due	3,409	4,321
90 Days or More Past Due	27,123	38,739
Total Past Due	33,303	45,195
Current	14,563	14,164
Total loans	47,866	59,359
Nonaccrual Loan [Member] | Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	4,541	3,744
60-89 Days Past Due	5,504	6,980
90 Days or More Past Due	41,402	67,799
Total Past Due	51,447	78,523
Current	23,131	21,889
Total loans	$ 74,578	$ 100,412