Loans Part 7 (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
Financing receivable, recorded investment, aging [Abstract]
Current	$ 11,245,244	$ 10,846,838	$ 10,364,210
Past due 30 to 89 days	58,888	63,822	48,519
Past due 90 days or more	127,817	157,797	124,645
Nonaccrual	144,482	201,286	200,170
Total	11,576,431	11,269,743	10,737,544
Commercial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	7,004,707	6,465,447	6,109,765
Past due 30 to 89 days	13,171	19,125	4,978
Past due 90 days or more	137	1,687	2,137
Nonaccrual	34,529	68,811	53,365
Total	7,052,544	6,555,070	6,170,245
Commercial [Member] | Energy [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	2,272,989	2,003,192	1,709,608
Past due 30 to 89 days	2,260	1,065	153
Past due 90 days or more	0	448	0
Nonaccrual	3,087	336	345
Total	2,278,336	2,005,041	1,710,106
Commercial [Member] | Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,917,655	1,729,775	1,703,683
Past due 30 to 89 days	3,705	13,608	3,759
Past due 90 days or more	37	1,187	1,593
Nonaccrual	10,123	16,968	16,254
Total	1,931,520	1,761,538	1,725,289
Commercial [Member] | Wholesale/Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	954,475	945,776	1,027,827
Past due 30 to 89 days	1,534	470	697
Past due 90 days or more	0	0	487
Nonaccrual	4,175	21,180	25,138
Total	960,184	967,426	1,054,149
Commercial [Member] | Manufacturing [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	350,647	313,028	363,048
Past due 30 to 89 days	0	654	0
Past due 90 days or more	0	0	0
Nonaccrual	12,230	23,051	4,366
Total	362,877	336,733	367,414
Commercial [Member] | Healthcare [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,005,538	971,265	849,605
Past due 30 to 89 days	180	1,362	177
Past due 90 days or more	100	47	0
Nonaccrual	3,310	5,486	5,962
Total	1,009,128	978,160	855,744
Commercial [Member] | Integrated Food Services [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	212,075	204,306	187,833
Past due 30 to 89 days	4,903	0	0
Past due 90 days or more	0	5	0
Nonaccrual	0	0	0
Total	216,978	204,311	187,833
Commercial [Member] | Other Commercial and Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	291,328	298,105	268,161
Past due 30 to 89 days	589	1,966	192
Past due 90 days or more	0	0	57
Nonaccrual	1,604	1,790	1,300
Total	293,521	301,861	269,710
Commercial Real Estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	2,034,586	2,186,601	2,067,152
Past due 30 to 89 days	11,414	5,372	10,341
Past due 90 days or more	0	137	175
Nonaccrual	80,214	99,193	110,363
Total	2,126,214	2,291,303	2,188,031
Commercial Real Estate [Member] | Construction and Land Development [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	240,208	278,901	293,627
Past due 30 to 89 days	801	1,279	2,333
Past due 90 days or more	0	0	0
Nonaccrual	46,050	61,874	76,265
Total	287,059	342,054	372,225
Commercial Real Estate [Member] | Retail [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	478,843	502,167	442,231
Past due 30 to 89 days	5,626	372	2,911
Past due 90 days or more	0	0	0
Nonaccrual	7,908	6,863	4,642
Total	492,377	509,402	449,784
Commercial Real Estate [Member] | Office [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	373,278	394,227	471,938
Past due 30 to 89 days	525	239	2,320
Past due 90 days or more	0	0	0
Nonaccrual	10,589	11,457	11,473
Total	384,392	405,923	485,731
Commercial Real Estate [Member] | Multifamily [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	358,204	365,477	329,824
Past due 30 to 89 days	742	38	0
Past due 90 days or more	0	0	0
Nonaccrual	3,219	3,513	4,717
Total	362,165	369,028	334,541
Commercial Real Estate [Member] | Industrial [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	230,641	278,186	159,422
Past due 30 to 89 days	392	0	384
Past due 90 days or more	0	0	0
Nonaccrual	0	0	0
Total	231,033	278,186	159,806
Commercial Real Estate [Member] | Other Commercial Real Estate [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	353,412	367,643	370,110
Past due 30 to 89 days	3,328	3,444	2,393
Past due 90 days or more	0	137	175
Nonaccrual	12,448	15,486	13,266
Total	369,188	386,710	385,944
Residential Mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,822,891	1,756,358	1,693,036
Past due 30 to 89 days	31,814	32,458	24,913
Past due 90 days or more	127,665	155,944	122,312
Nonaccrual	22,727	29,767	31,693
Total	2,005,097	1,974,527	1,871,954
Residential Mortgage [Member] | Permanent Residential Mortgage [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	1,107,610	1,110,418	1,108,565
Past due 30 to 89 days	15,130	17,259	18,735
Past due 90 days or more	495	601	0
Nonaccrual	18,136	25,366	27,991
Total	1,141,371	1,153,644	1,155,291
Residential Mortgage [Member] | Permanent Mortgages Guaranteed by US Government Agencies [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	26,460	20,998	8,426
Past due 30 to 89 days	14,473	12,163	3,728
Past due 90 days or more	127,126	155,301	122,304
Nonaccrual	0	0	0
Total	168,059	188,462	134,458
Residential Mortgage [Member] | Home Equity [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	688,821	624,942	576,045
Past due 30 to 89 days	2,211	3,036	2,450
Past due 90 days or more	44	42	8
Nonaccrual	4,591	4,401	3,702
Total	695,667	632,421	582,205
Consumer [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	383,060	438,432	494,257
Past due 30 to 89 days	2,489	6,867	8,287
Past due 90 days or more	15	29	21
Nonaccrual	7,012	3,515	4,749
Total	392,576	448,843	507,314
Consumer [Member] | Indirect Automobile [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	58,895	98,345	152,496
Past due 30 to 89 days	1,771	4,581	7,256
Past due 90 days or more	1	29	19
Nonaccrual	2,257	2,194	2,729
Total	62,924	105,149	162,500
Consumer [Member] | Other Consumer [Member]
Financing receivable, recorded investment, aging [Abstract]
Current	324,165	340,087	341,761
Past due 30 to 89 days	718	2,286	1,031
Past due 90 days or more	14	0	2
Nonaccrual	4,755	1,321	2,020
Total	$ 329,652	$ 343,694	$ 344,814