Loans, Allowance for Loan Losses, and Credit Quality (Details 6) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Summarized details of Loans
30-59 Days Past Due	$ 66,935	$ 63,973
60-89 Days Past Due	21,050	26,720
90 Days or More Past Due	120,425	134,445
Total Past Due	208,410	225,138
Current	15,343,152	15,185,884
Total loans	15,551,562	15,411,022
Commercial And Industrial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	10,862	18,116
60-89 Days Past Due	3,276	2,573
90 Days or More Past Due	10,206	12,041
Total Past Due	24,344	32,730
Current	4,626,799	4,469,291
Total loans	4,651,143	4,502,021
Commercial Real Estate Owner Occupied Portfolio [Member]
Summarized details of Loans
30-59 Days Past Due	8,163	11,909
60-89 Days Past Due	2,175	2,382
90 Days or More Past Due	12,316	12,127
Total Past Due	22,654	26,418
Current	1,176,859	1,193,329
Total loans	1,199,513	1,219,747
Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	12	15
60-89 Days Past Due	281	12
90 Days or More Past Due	17	9
Total Past Due	310	36
Current	57,598	64,160
Total loans	57,908	64,196
Commercial And Business Lending [Member]
Summarized details of Loans
30-59 Days Past Due	19,037	30,040
60-89 Days Past Due	5,732	4,967
90 Days or More Past Due	22,539	24,177
Total Past Due	47,308	59,184
Current	5,861,256	5,726,780
Total loans	5,908,564	5,785,964
Commercial Real Estate Investor Portfolio Segment [Member]
Summarized details of Loans
30-59 Days Past Due	26,698	8,621
60-89 Days Past Due	4,521	8,120
90 Days or More Past Due	35,550	31,294
Total Past Due	66,769	48,035
Current	2,833,398	2,858,724
Total loans	2,900,167	2,906,759
Commercial Real Estate Construction Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	4,450	1,644
60-89 Days Past Due	303	1,527
90 Days or More Past Due	4,620	9,922
Total Past Due	9,373	13,093
Current	719,772	642,288
Total loans	729,145	655,381
Commercial Real Estate Lending [Member]
Summarized details of Loans
30-59 Days Past Due	31,148	10,265
60-89 Days Past Due	4,824	9,647
90 Days or More Past Due	40,170	41,216
Total Past Due	76,142	61,128
Current	3,553,170	3,501,012
Total loans	3,629,312	3,562,140
Commercial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	50,185	40,305
60-89 Days Past Due	10,556	14,614
90 Days or More Past Due	62,709	65,393
Total Past Due	123,450	120,312
Current	9,414,426	9,227,792
Total loans	9,537,876	9,348,104
Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	4,091	11,607
60-89 Days Past Due	4,835	5,905
90 Days or More Past Due	23,629	28,570
Total Past Due	32,555	46,082
Current	2,065,852	2,173,412
Total loans	2,098,407	2,219,494
Installment [Member]
Summarized details of Loans
30-59 Days Past Due	2,166	1,453
60-89 Days Past Due	579	950
90 Days or More Past Due	1,342	1,599
Total Past Due	4,087	4,002
Current	443,358	462,725
Total loans	447,445	466,727
Residential, Prime, Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	10,493	10,608
60-89 Days Past Due	5,080	5,251
90 Days or More Past Due	32,745	38,883
Total Past Due	48,318	54,742
Current	3,419,516	3,321,955
Total loans	3,467,834	3,376,697
Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	16,750	23,668
60-89 Days Past Due	10,494	12,106
90 Days or More Past Due	57,716	69,052
Total Past Due	84,960	104,826
Current	5,928,726	5,958,092
Total loans	6,013,686	6,062,918
Accruing Loans [Member]
Summarized details of Loans
30-59 Days Past Due	49,405	49,953
60-89 Days Past Due	13,275	14,128
90 Days or More Past Due	5,690	2,289
Total Past Due	68,370	66,370
Current	15,257,756	15,091,784
Total loans	15,326,126	15,158,154
Accruing Loans [Member] | Commercial And Industrial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	7,470	9,557
60-89 Days Past Due	2,793	1,782
90 Days or More Past Due	210	79
Total Past Due	10,473	11,418
Current	4,607,428	4,451,421
Total loans	4,617,901	4,462,839
Accruing Loans [Member] | Commercial Real Estate Owner Occupied Portfolio [Member]
Summarized details of Loans
30-59 Days Past Due	5,286	10,420
60-89 Days Past Due	1,518	633
90 Days or More Past Due	2,389	308
Total Past Due	9,193	11,361
Current	1,167,121	1,184,132
Total loans	1,176,314	1,195,493
Accruing Loans [Member] | Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	2	0
60-89 Days Past Due	281	12
90 Days or More Past Due	0	0
Total Past Due	283	12
Current	55,460	61,153
Total loans	55,743	61,165
Accruing Loans [Member] | Commercial And Business Lending [Member]
Summarized details of Loans
30-59 Days Past Due	12,758	19,977
60-89 Days Past Due	4,592	2,427
90 Days or More Past Due	2,599	387
Total Past Due	19,949	22,791
Current	5,830,009	5,696,706
Total loans	5,849,958	5,719,497
Accruing Loans [Member] | Commercial Real Estate Investor Portfolio Segment [Member]
Summarized details of Loans
30-59 Days Past Due	21,801	8,424
60-89 Days Past Due	3,400	5,048
90 Days or More Past Due	1,922	366
Total Past Due	27,123	13,838
Current	2,816,268	2,834,234
Total loans	2,843,391	2,848,072
Accruing Loans [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	1,993	1,628
60-89 Days Past Due	294	1,527
90 Days or More Past Due	74	283
Total Past Due	2,361	3,438
Current	704,618	624,641
Total loans	706,979	628,079
Accruing Loans [Member] | Commercial Real Estate Lending [Member]
Summarized details of Loans
30-59 Days Past Due	23,794	10,052
60-89 Days Past Due	3,694	6,575
90 Days or More Past Due	1,996	649
Total Past Due	29,484	17,276
Current	3,520,886	3,458,875
Total loans	3,550,370	3,476,151
Accruing Loans [Member] | Commercial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	36,552	30,029
60-89 Days Past Due	8,286	9,002
90 Days or More Past Due	4,595	1,036
Total Past Due	49,433	40,067
Current	9,350,895	9,155,581
Total loans	9,400,328	9,195,648
Accruing Loans [Member] | Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	3,412	10,151
60-89 Days Past Due	3,137	3,387
90 Days or More Past Due	93	96
Total Past Due	6,642	13,634
Current	2,057,820	2,166,645
Total loans	2,064,462	2,180,279
Accruing Loans [Member] | Installment [Member]
Summarized details of Loans
30-59 Days Past Due	2,042	1,300
60-89 Days Past Due	458	809
90 Days or More Past Due	858	1,013
Total Past Due	3,358	3,122
Current	442,325	461,767
Total loans	445,683	464,889
Accruing Loans [Member] | Residential, Prime, Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	7,399	8,473
60-89 Days Past Due	1,394	930
90 Days or More Past Due	144	144
Total Past Due	8,937	9,547
Current	3,406,716	3,307,791
Total loans	3,415,653	3,317,338
Accruing Loans [Member] | Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	12,853	19,924
60-89 Days Past Due	4,989	5,126
90 Days or More Past Due	1,095	1,253
Total Past Due	18,937	26,303
Current	5,906,861	5,936,203
Total loans	5,925,798	5,962,506
Nonaccrual Loan [Member]
Summarized details of Loans
30-59 Days Past Due	17,530	14,020
60-89 Days Past Due	7,775	12,592
90 Days or More Past Due	114,735	132,156
Total Past Due	140,040	158,768
Current	85,396	94,100
Total loans	225,436	252,868
Nonaccrual Loan [Member] | Commercial And Industrial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	3,392	8,559
60-89 Days Past Due	483	791
90 Days or More Past Due	9,996	11,962
Total Past Due	13,871	21,312
Current	19,371	17,870
Total loans	33,242	39,182
Nonaccrual Loan [Member] | Commercial Real Estate Owner Occupied Portfolio [Member]
Summarized details of Loans
30-59 Days Past Due	2,877	1,489
60-89 Days Past Due	657	1,749
90 Days or More Past Due	9,927	11,819
Total Past Due	13,461	15,057
Current	9,738	9,197
Total loans	23,199	24,254
Nonaccrual Loan [Member] | Finance Leases Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	10	15
60-89 Days Past Due	0	0
90 Days or More Past Due	17	9
Total Past Due	27	24
Current	2,138	3,007
Total loans	2,165	3,031
Nonaccrual Loan [Member] | Commercial And Business Lending [Member]
Summarized details of Loans
30-59 Days Past Due	6,279	10,063
60-89 Days Past Due	1,140	2,540
90 Days or More Past Due	19,940	23,790
Total Past Due	27,359	36,393
Current	31,247	30,074
Total loans	58,606	66,467
Nonaccrual Loan [Member] | Commercial Real Estate Investor Portfolio Segment [Member]
Summarized details of Loans
30-59 Days Past Due	4,897	197
60-89 Days Past Due	1,121	3,072
90 Days or More Past Due	33,628	30,928
Total Past Due	39,646	34,197
Current	17,130	24,490
Total loans	56,776	58,687
Nonaccrual Loan [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	2,457	16
60-89 Days Past Due	9	0
90 Days or More Past Due	4,546	9,639
Total Past Due	7,012	9,655
Current	15,154	17,647
Total loans	22,166	27,302
Nonaccrual Loan [Member] | Commercial Real Estate Lending [Member]
Summarized details of Loans
30-59 Days Past Due	7,354	213
60-89 Days Past Due	1,130	3,072
90 Days or More Past Due	38,174	40,567
Total Past Due	46,658	43,852
Current	32,284	42,137
Total loans	78,942	85,989
Nonaccrual Loan [Member] | Commercial Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	13,633	10,276
60-89 Days Past Due	2,270	5,612
90 Days or More Past Due	58,114	64,357
Total Past Due	74,017	80,245
Current	63,531	72,211
Total loans	137,548	152,456
Nonaccrual Loan [Member] | Home Equity [Member]
Summarized details of Loans
30-59 Days Past Due	679	1,456
60-89 Days Past Due	1,698	2,518
90 Days or More Past Due	23,536	28,474
Total Past Due	25,913	32,448
Current	8,032	6,767
Total loans	33,945	39,215
Nonaccrual Loan [Member] | Installment [Member]
Summarized details of Loans
30-59 Days Past Due	124	153
60-89 Days Past Due	121	141
90 Days or More Past Due	484	586
Total Past Due	729	880
Current	1,033	958
Total loans	1,762	1,838
Nonaccrual Loan [Member] | Residential, Prime, Financing Receivable [Member]
Summarized details of Loans
30-59 Days Past Due	3,094	2,135
60-89 Days Past Due	3,686	4,321
90 Days or More Past Due	32,601	38,739
Total Past Due	39,381	45,195
Current	12,800	14,164
Total loans	52,181	59,359
Nonaccrual Loan [Member] | Consumer Loan [Member]
Summarized details of Loans
30-59 Days Past Due	3,897	3,744
60-89 Days Past Due	5,505	6,980
90 Days or More Past Due	56,621	67,799
Total Past Due	66,023	78,523
Current	21,865	21,889
Total loans	$ 87,888	$ 100,412