Loans and Allowance for Credit Losses Past Due Loan Status and Non-Accrual Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
>90 Days Past Due and Accruing	$ 11,505	$ 15,291
Non-accrual	120,133	129,523
Total Past Due	186,787	196,741
Current	14,512,485	13,641,861
Loans, net of unearned income	14,699,272	13,838,602
Commercial – industrial, financial and agricultural
>90 Days Past Due and Accruing	1,111	1,872
Non-accrual	42,349	42,199
Total Past Due	53,669	52,933
Current	4,033,817	4,036,029
Loans, net of unearned income	4,087,486	4,088,962
Real estate – commercial mortgage
>90 Days Past Due and Accruing	383	439
Non-accrual	38,936	40,731
Total Past Due	47,195	48,951
Current	5,971,387	5,413,379
Loans, net of unearned income	6,018,582	5,462,330
Commercial - secured
>90 Days Past Due and Accruing	959	1,853
Non-accrual	41,589	41,498
Total Past Due	51,824	51,620
Current	3,881,728	3,874,493
Loans, net of unearned income	3,933,552	3,926,113
Commercial - unsecured
>90 Days Past Due and Accruing	152	19
Non-accrual	760	701
Total Past Due	1,845	1,313
Current	152,089	161,536
Loans, net of unearned income	153,934	162,849
Real estate – home equity
>90 Days Past Due and Accruing	2,543	3,473
Non-accrual	10,611	11,210
Total Past Due	22,428	23,666
Current	1,602,687	1,660,773
Loans, net of unearned income	1,625,115	1,684,439
Real estate – residential mortgage
>90 Days Past Due and Accruing	5,224	6,570
Non-accrual	18,431	21,914
Total Past Due	43,999	46,789
Current	1,557,995	1,329,371
Loans, net of unearned income	1,601,994	1,376,160
Real estate – construction
>90 Days Past Due and Accruing	36	416
Non-accrual	9,806	12,044
Total Past Due	10,869	14,634
Current	832,780	785,354
Loans, net of unearned income	843,649	799,988
Construction - commercial residential
>90 Days Past Due and Accruing	36	0
Non-accrual	8,275	11,213
Total Past Due	8,595	13,073
Current	133,594	166,230
Loans, net of unearned income	142,189	179,303
Construction - commercial
>90 Days Past Due and Accruing	0	0
Non-accrual	435	638
Total Past Due	1,178	864
Current	643,312	559,127
Loans, net of unearned income	644,490	559,991
Construction - other
>90 Days Past Due and Accruing	0	416
Non-accrual	1,096	193
Total Past Due	1,096	697
Current	55,874	59,997
Loans, net of unearned income	56,970	60,694
Consumer
>90 Days Past Due and Accruing	1,891	2,440
Non-accrual	0	0
Total Past Due	7,242	7,503
Current	284,228	261,085
Loans, net of unearned income	291,470	268,588
Consumer - direct
>90 Days Past Due and Accruing	1,563	2,203
Non-accrual	0	0
Total Past Due	3,315	4,457
Current	93,572	94,262
Loans, net of unearned income	96,887	98,719
Consumer - indirect
>90 Days Past Due and Accruing	328	237
Non-accrual	0	0
Total Past Due	3,927	3,046
Current	190,656	166,823
Loans, net of unearned income	194,583	169,869
Leasing and other and overdrafts
>90 Days Past Due and Accruing	317	81
Non-accrual	0	1,425
Total Past Due	1,385	2,265
Current	229,591	155,870
Loans, net of unearned income	230,976	158,135
30-59 Days Past Due
Total Past Due	41,938	40,194
30-59 Days Past Due | Commercial – industrial, financial and agricultural
Total Past Due	7,558	6,164
30-59 Days Past Due | Real estate – commercial mortgage
Total Past Due	6,254	6,469
30-59 Days Past Due | Commercial - secured
Total Past Due	6,660	5,654
30-59 Days Past Due | Commercial - unsecured
Total Past Due	898	510
30-59 Days Past Due | Real estate – home equity
Total Past Due	6,596	6,438
30-59 Days Past Due | Real estate – residential mortgage
Total Past Due	15,600	15,141
30-59 Days Past Due | Real estate – construction
Total Past Due	976	1,504
30-59 Days Past Due | Construction - commercial residential
Total Past Due	233	1,366
30-59 Days Past Due | Construction - commercial
Total Past Due	743	50
30-59 Days Past Due | Construction - other
Total Past Due	0	88
30-59 Days Past Due | Consumer
Total Past Due	4,411	3,995
30-59 Days Past Due | Consumer - direct
Total Past Due	1,211	1,687
30-59 Days Past Due | Consumer - indirect
Total Past Due	3,200	2,308
30-59 Days Past Due | Leasing and other and overdrafts
Total Past Due	543	483
60-89 Days Past Due
Total Past Due	13,211	11,733
60-89 Days Past Due | Commercial – industrial, financial and agricultural
Total Past Due	2,651	2,698
60-89 Days Past Due | Real estate – commercial mortgage
Total Past Due	1,622	1,312
60-89 Days Past Due | Commercial - secured
Total Past Due	2,616	2,615
60-89 Days Past Due | Commercial - unsecured
Total Past Due	35	83
60-89 Days Past Due | Real estate – home equity
Total Past Due	2,678	2,545
60-89 Days Past Due | Real estate – residential mortgage
Total Past Due	4,744	3,164
60-89 Days Past Due | Real estate – construction
Total Past Due	51	670
60-89 Days Past Due | Construction - commercial residential
Total Past Due	51	494
60-89 Days Past Due | Construction - commercial
Total Past Due	0	176
60-89 Days Past Due | Construction - other
Total Past Due	0	0
60-89 Days Past Due | Consumer
Total Past Due	940	1,068
60-89 Days Past Due | Consumer - direct
Total Past Due	541	567
60-89 Days Past Due | Consumer - indirect
Total Past Due	399	501
60-89 Days Past Due | Leasing and other and overdrafts
Total Past Due	525	276
Total ≥ 90 Days
Total Past Due	131,638	144,814
Total ≥ 90 Days | Commercial – industrial, financial and agricultural
Total Past Due	43,460	44,071
Total ≥ 90 Days | Real estate – commercial mortgage
Total Past Due	39,319	41,170
Total ≥ 90 Days | Commercial - secured
Total Past Due	42,548	43,351
Total ≥ 90 Days | Commercial - unsecured
Total Past Due	912	720
Total ≥ 90 Days | Real estate – home equity
Total Past Due	13,154	14,683
Total ≥ 90 Days | Real estate – residential mortgage
Total Past Due	23,655	28,484
Total ≥ 90 Days | Real estate – construction
Total Past Due	9,842	12,460
Total ≥ 90 Days | Construction - commercial residential
Total Past Due	8,311	11,213
Total ≥ 90 Days | Construction - commercial
Total Past Due	435	638
Total ≥ 90 Days | Construction - other
Total Past Due	1,096	609
Total ≥ 90 Days | Consumer
Total Past Due	1,891	2,440
Total ≥ 90 Days | Consumer - direct
Total Past Due	1,563	2,203
Total ≥ 90 Days | Consumer - indirect
Total Past Due	328	237
Total ≥ 90 Days | Leasing and other and overdrafts
Total Past Due	$ 317	$ 1,506