Loans and Allowance for Credit Losses Past Due Loan Status and Non-Accrual Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
>90 Days Past Due and Accruing	$ 15,291	$ 17,402
Non-accrual	129,523	121,080
Total Past Due	196,741	206,828
Current	13,641,861	12,904,888
Loans, net of unearned income	13,838,602	13,111,716
Commercial – industrial, financial and agricultural
>90 Days Past Due and Accruing	1,872	619
Non-accrual	42,199	29,769
Total Past Due	52,933	36,645
Current	4,036,029	3,688,922
Loans, net of unearned income	4,088,962	3,725,567
Real estate – commercial mortgage
>90 Days Past Due and Accruing	439	800
Non-accrual	40,731	44,437
Total Past Due	48,951	63,313
Current	5,413,379	5,133,842
Loans, net of unearned income	5,462,330	5,197,155
Commercial - secured
>90 Days Past Due and Accruing	1,853	610
Non-accrual	41,498	28,747
Total Past Due	51,620	35,154
Current	3,874,493	3,529,460
Loans, net of unearned income	3,926,113	3,564,614
Commercial - unsecured
>90 Days Past Due and Accruing	19	9
Non-accrual	701	1,022
Total Past Due	1,313	1,491
Current	161,536	159,462
Loans, net of unearned income	162,849	160,953
Real estate – home equity
>90 Days Past Due and Accruing	3,473	4,257
Non-accrual	11,210	10,483
Total Past Due	23,666	25,671
Current	1,660,773	1,711,017
Loans, net of unearned income	1,684,439	1,736,688
Real estate – residential mortgage
>90 Days Past Due and Accruing	6,570	8,952
Non-accrual	21,914	20,043
Total Past Due	46,789	55,929
Current	1,329,371	1,321,139
Loans, net of unearned income	1,376,160	1,377,068
Real estate – construction
>90 Days Past Due and Accruing	416	51
Non-accrual	12,044	16,348
Total Past Due	14,634	16,559
Current	785,354	674,042
Loans, net of unearned income	799,988	690,601
Construction - commercial residential
>90 Days Past Due and Accruing	0	0
Non-accrual	11,213	13,463
Total Past Due	13,073	13,623
Current	166,230	190,047
Loans, net of unearned income	179,303	203,670
Construction - commercial
>90 Days Past Due and Accruing	0	0
Non-accrual	638	2,604
Total Past Due	864	2,604
Current	559,127	424,815
Loans, net of unearned income	559,991	427,419
Construction - other
>90 Days Past Due and Accruing	416	51
Non-accrual	193	281
Total Past Due	697	332
Current	59,997	59,180
Loans, net of unearned income	60,694	59,512
Consumer
>90 Days Past Due and Accruing	2,440	2,590
Non-accrual	0	0
Total Past Due	7,503	8,055
Current	261,085	257,376
Loans, net of unearned income	268,588	265,431
Consumer - direct
>90 Days Past Due and Accruing	2,203	2,414
Non-accrual	0	0
Total Past Due	4,457	5,305
Current	94,262	104,018
Loans, net of unearned income	98,719	109,323
Consumer - indirect
>90 Days Past Due and Accruing	237	176
Non-accrual	0	0
Total Past Due	3,046	2,750
Current	166,823	153,358
Loans, net of unearned income	169,869	156,108
Leasing and other and overdrafts
>90 Days Past Due and Accruing	81	133
Non-accrual	1,425	0
Total Past Due	2,265	656
Current	155,870	118,550
Loans, net of unearned income	158,135	119,206
30-59 Days Past Due
Total Past Due	40,194	51,177
30-59 Days Past Due | Commercial – industrial, financial and agricultural
Total Past Due	6,164	5,234
30-59 Days Past Due | Real estate – commercial mortgage
Total Past Due	6,469	14,399
30-59 Days Past Due | Commercial - secured
Total Past Due	5,654	4,839
30-59 Days Past Due | Commercial - unsecured
Total Past Due	510	395
30-59 Days Past Due | Real estate – home equity
Total Past Due	6,438	8,048
30-59 Days Past Due | Real estate – residential mortgage
Total Past Due	15,141	18,789
30-59 Days Past Due | Real estate – construction
Total Past Due	1,504	160
30-59 Days Past Due | Construction - commercial residential
Total Past Due	1,366	160
30-59 Days Past Due | Construction - commercial
Total Past Due	50	0
30-59 Days Past Due | Construction - other
Total Past Due	88	0
30-59 Days Past Due | Consumer
Total Past Due	3,995	4,190
30-59 Days Past Due | Consumer - direct
Total Past Due	1,687	2,034
30-59 Days Past Due | Consumer - indirect
Total Past Due	2,308	2,156
30-59 Days Past Due | Leasing and other and overdrafts
Total Past Due	483	357
60-89 Days Past Due
Total Past Due	11,733	17,169
60-89 Days Past Due | Commercial – industrial, financial and agricultural
Total Past Due	2,698	1,023
60-89 Days Past Due | Real estate – commercial mortgage
Total Past Due	1,312	3,677
60-89 Days Past Due | Commercial - secured
Total Past Due	2,615	958
60-89 Days Past Due | Commercial - unsecured
Total Past Due	83	65
60-89 Days Past Due | Real estate – home equity
Total Past Due	2,545	2,883
60-89 Days Past Due | Real estate – residential mortgage
Total Past Due	3,164	8,145
60-89 Days Past Due | Real estate – construction
Total Past Due	670	0
60-89 Days Past Due | Construction - commercial residential
Total Past Due	494	0
60-89 Days Past Due | Construction - commercial
Total Past Due	176	0
60-89 Days Past Due | Construction - other
Total Past Due	0	0
60-89 Days Past Due | Consumer
Total Past Due	1,068	1,275
60-89 Days Past Due | Consumer - direct
Total Past Due	567	857
60-89 Days Past Due | Consumer - indirect
Total Past Due	501	418
60-89 Days Past Due | Leasing and other and overdrafts
Total Past Due	276	166
Total ≥ 90 Days
Total Past Due	144,814	138,482
Total ≥ 90 Days | Commercial – industrial, financial and agricultural
Total Past Due	44,071	30,388
Total ≥ 90 Days | Real estate – commercial mortgage
Total Past Due	41,170	45,237
Total ≥ 90 Days | Commercial - secured
Total Past Due	43,351	29,357
Total ≥ 90 Days | Commercial - unsecured
Total Past Due	720	1,031
Total ≥ 90 Days | Real estate – home equity
Total Past Due	14,683	14,740
Total ≥ 90 Days | Real estate – residential mortgage
Total Past Due	28,484	28,995
Total ≥ 90 Days | Real estate – construction
Total Past Due	12,460	16,399
Total ≥ 90 Days | Construction - commercial residential
Total Past Due	11,213	13,463
Total ≥ 90 Days | Construction - commercial
Total Past Due	638	2,604
Total ≥ 90 Days | Construction - other
Total Past Due	609	332
Total ≥ 90 Days | Consumer
Total Past Due	2,440	2,590
Total ≥ 90 Days | Consumer - direct
Total Past Due	2,203	2,414
Total ≥ 90 Days | Consumer - indirect
Total Past Due	237	176
Total ≥ 90 Days | Leasing and other and overdrafts
Total Past Due	$ 1,506	$ 133