Loans and Allowance for Credit Losses Past Due Loan Status and Non-Accrual Loans by Portfolio Segment (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
31-59 Days Past Due	$ 59,044	$ 62,810
60-89 Days Past Due	26,367	43,583
>90 Days Past Due and Accruing	35,270	28,767
Non-accrual	248,719	257,761
Total >90 Days	283,989	286,528
Total Past Due	369,400	392,921
Current	11,588,200	11,576,049
Total	11,957,600	11,968,970	11,873,208
Commercial - industrial, financial, and agricultural
31-59 Days Past Due	7,238	9,955
60-89 Days Past Due	5,181	5,013
>90 Days Past Due and Accruing	6,272	5,240
Non-accrual	76,612	75,704
Total >90 Days	82,884	80,944
Total Past Due	95,303	95,912
Current	3,422,925	3,543,456
Total	3,518,228	3,639,368
Real-estate commercial mortage [Member]
31-59 Days Past Due	13,925	11,167
60-89 Days Past Due	5,796	14,437
>90 Days Past Due and Accruing	5,564	4,394
Non-accrual	98,512	109,412
Total >90 Days	104,076	113,806
Total Past Due	123,797	139,410
Current	4,510,631	4,463,186
Total	4,634,428	4,602,596
Commercial - secured [Member]
31-59 Days Past Due	6,739	9,284
60-89 Days Past Due	4,712	4,498
>90 Days Past Due and Accruing	6,202	4,831
Non-accrual	73,687	73,048
Total >90 Days	79,889	77,879
Total Past Due	91,340	91,661
Current	3,204,305	3,301,899
Total	3,295,645	3,393,560
Commercial - unsecured [Member]
31-59 Days Past Due	499	671
60-89 Days Past Due	469	515
>90 Days Past Due and Accruing	70	409
Non-accrual	2,925	2,656
Total >90 Days	2,995	3,065
Total Past Due	3,963	4,251
Current	218,620	241,557
Total	222,583	245,808
Real-estate - home equity [Member]
31-59 Days Past Due	8,826	7,439
60-89 Days Past Due	2,966	4,194
>90 Days Past Due and Accruing	5,167	5,714
Non-accrual	5,747	5,493
Total >90 Days	10,914	11,207
Total Past Due	22,706	22,840
Current	1,579,174	1,601,722
Total	1,601,880	1,624,562
Real-estate - residential mortgage [Member]
31-59 Days Past Due	22,838	23,877
60-89 Days Past Due	9,698	13,246
>90 Days Past Due and Accruing	15,274	8,502
Non-accrual	7,742	7,834
Total >90 Days	23,016	16,336
Total Past Due	55,552	53,459
Current	1,121,395	1,043,733
Total	1,176,947	1,097,192
Real-estate - construction
31-59 Days Past Due	2,500	4,744
60-89 Days Past Due	1,150	4,824
>90 Days Past Due and Accruing	210	1,850
Non-accrual	59,707	58,894
Total >90 Days	59,917	60,744
Total Past Due	63,567	70,312
Current	584,133	545,133
Total	647,700	615,445
Construction - commercial residential [Member]
31-59 Days Past Due	2,329	2,372
60-89 Days Past Due	478	4,824
>90 Days Past Due and Accruing	0	1,656
Non-accrual	52,372	53,420
Total >90 Days	52,372	55,076
Total Past Due	55,179	62,272
Current	301,431	290,665
Total	356,610	352,937
Construction - commercial [Member]
31-59 Days Past Due	0	31
60-89 Days Past Due	0	0
>90 Days Past Due and Accruing	128	128
Non-accrual	6,163	4,347
Total >90 Days	6,291	4,475
Total Past Due	6,291	4,506
Current	228,278	204,875
Total	234,569	209,381
Construction other [Member]
31-59 Days Past Due	171	2,341
60-89 Days Past Due	672	0
>90 Days Past Due and Accruing	82	66
Non-accrual	1,172	1,127
Total >90 Days	1,254	1,193
Total Past Due	2,097	3,534
Current	54,424	49,593
Total	56,521	53,127
Total Consumer
31-59 Days Past Due	3,329	4,703
60-89 Days Past Due	1,487	1,745
>90 Days Past Due and Accruing	2,468	3,016
Non-accrual	366	368
Total >90 Days	2,834	3,384
Total Past Due	7,650	9,832
Current	300,845	308,269
Total	308,495	318,101
Consumer - direct [Member]
31-59 Days Past Due	377	455
60-89 Days Past Due	128	202
>90 Days Past Due and Accruing	41	150
Non-accrual	366	368
Total >90 Days	407	518
Total Past Due	912	1,175
Current	31,529	34,263
Total	32,441	35,438
Consumer - Indirect [Member]
31-59 Days Past Due	1,211	1,997
60-89 Days Past Due	307	440
>90 Days Past Due and Accruing	81	183
Non-accrual	0	0
Total >90 Days	81	183
Total Past Due	1,599	2,620
Current	146,798	151,112
Total	148,397	153,732
Consumer Other [Member]
31-59 Days Past Due	1,741	2,251
60-89 Days Past Due	1,052	1,103
>90 Days Past Due and Accruing	2,346	2,683
Non-accrual	0	0
Total >90 Days	2,346	2,683
Total Past Due	5,139	6,037
Current	122,518	122,894
Total	127,657	128,931
Leasing and other and overdrafts [Member]
31-59 Days Past Due	388	925
60-89 Days Past Due	89	124
>90 Days Past Due and Accruing	315	51
Non-accrual	33	56
Total >90 Days	348	107
Total Past Due	825	1,156
Current	69,097	70,550
Total	$ 69,922	$ 71,706