Loans and Allowance for Credit Losses Past Due Loan Status and Non-Accrual Loans by Portfolio Segment (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
31-59 Days Past Due	$ 66,448	$ 59,634
60-89 Days Past Due	17,493	31,223
>90 Days Past Due and Accruing	25,271	26,221
Non-accrual	143,012	184,832
Total >90 Days	168,283	211,053
Total Past Due	252,224	301,910
Current	12,528,675	11,845,061
Loans, net of unearned income	12,780,899	12,146,971	11,935,260
Real-estate commercial mortage [Member]
31-59 Days Past Due	17,060	12,993
60-89 Days Past Due	2,951	8,473
>90 Days Past Due and Accruing	3,745	2,160
Non-accrual	38,878	54,960
Total >90 Days	42,623	57,120
Total Past Due	62,634	78,586
Current	5,000,739	4,585,840
Loans, net of unearned income	5,063,373	4,664,426
Commercial - industrial, financial, and agricultural
31-59 Days Past Due	10,127	8,474
60-89 Days Past Due	1,641	8,042
>90 Days Past Due and Accruing	1,136	1,259
Non-accrual	44,048	65,695
Total >90 Days	45,184	66,954
Total Past Due	56,952	83,470
Current	3,588,318	3,528,595
Loans, net of unearned income	3,645,270	3,612,065
Commercial - Secured [Member]
31-59 Days Past Due	9,603	8,013
60-89 Days Past Due	1,333	8,030
>90 Days Past Due and Accruing	1,136	1,060
Non-accrual	42,927	63,602
Total >90 Days	44,063	64,662
Total Past Due	54,999	80,705
Current	3,384,535	3,332,739
Loans, net of unearned income	3,439,534	3,413,444
Commercial - unsecured [Member]
31-59 Days Past Due	524	461
60-89 Days Past Due	308	12
>90 Days Past Due and Accruing	0	199
Non-accrual	1,121	2,093
Total >90 Days	1,121	2,292
Total Past Due	1,953	2,765
Current	203,783	195,856
Loans, net of unearned income	205,736	198,621
Real-estate - home equity [Member]
31-59 Days Past Due	14,176	9,579
60-89 Days Past Due	4,042	3,066
>90 Days Past Due and Accruing	5,296	5,579
Non-accrual	13,395	11,625
Total >90 Days	18,691	17,204
Total Past Due	36,909	29,849
Current	1,736,645	1,602,541
Loans, net of unearned income	1,773,554	1,632,390
Real-estate - residential mortgage [Member]
31-59 Days Past Due	17,468	21,827
60-89 Days Past Due	6,634	10,296
>90 Days Past Due and Accruing	11,860	13,333
Non-accrual	22,449	21,103
Total >90 Days	34,309	34,436
Total Past Due	58,411	66,559
Current	1,269,058	1,190,873
Loans, net of unearned income	1,327,469	1,257,432
Real-estate - construction
31-59 Days Past Due	1,966	1,331
60-89 Days Past Due	339	0
>90 Days Past Due and Accruing	163	579
Non-accrual	24,233	31,426
Total >90 Days	24,396	32,005
Total Past Due	26,701	33,336
Current	550,641	550,782
Loans, net of unearned income	577,342	584,118
Construction - commercial residential [Member]
31-59 Days Past Due	233	466
60-89 Days Past Due	339	0
>90 Days Past Due and Accruing	163	251
Non-accrual	21,346	22,815
Total >90 Days	21,509	23,066
Total Past Due	22,081	23,532
Current	222,976	265,020
Loans, net of unearned income	245,057	288,552
Construction - Commercial [Member]
31-59 Days Past Due	308	0
60-89 Days Past Due	0	0
>90 Days Past Due and Accruing	0	0
Non-accrual	2,388	8,035
Total >90 Days	2,388	8,035
Total Past Due	2,696	8,035
Current	256,145	218,315
Loans, net of unearned income	258,841	226,350
Construction other [Member]
31-59 Days Past Due	1,425	865
60-89 Days Past Due	0	0
>90 Days Past Due and Accruing	0	328
Non-accrual	499	576
Total >90 Days	499	904
Total Past Due	1,924	1,769
Current	71,520	67,447
Loans, net of unearned income	73,444	69,216
Total Consumer
31-59 Days Past Due	5,357	4,768
60-89 Days Past Due	1,658	1,297
>90 Days Past Due and Accruing	3,004	3,302
Non-accrual	9	13
Total >90 Days	3,013	3,315
Total Past Due	10,028	9,380
Current	286,114	300,484
Loans, net of unearned income	296,142	309,864
Consumer - direct [Member]
31-59 Days Past Due	2,852	2,842
60-89 Days Past Due	1,205	953
>90 Days Past Due and Accruing	2,884	3,157
Non-accrual	7	13
Total >90 Days	2,891	3,170
Total Past Due	6,948	6,965
Current	138,373	159,616
Loans, net of unearned income	145,321	166,581
Consumer - Indirect [Member]
31-59 Days Past Due	2,505	1,926
60-89 Days Past Due	453	344
>90 Days Past Due and Accruing	120	145
Non-accrual	2	0
Total >90 Days	122	145
Total Past Due	3,080	2,415
Current	147,741	140,868
Loans, net of unearned income	150,821	143,283
Leasing and other and overdrafts [Member]
31-59 Days Past Due	294	662
60-89 Days Past Due	228	49
>90 Days Past Due and Accruing	67	9
Non-accrual	0	10
Total >90 Days	67	19
Total Past Due	589	730
Current	97,160	85,946
Loans, net of unearned income	$ 97,749	$ 86,676