Loans and Allowance for Credit Losses Past Due Loan Status and Non-Accrual Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
>90 Days Past Due and Accruing	$ 16,057	$ 11,106
Non-accrual	125,098	128,572
Current	16,620,575	15,957,429
Loans and leases, net of unearned income	16,837,526	16,165,800
Commercial – industrial, financial and agricultural
>90 Days Past Due and Accruing	1,385	1,119
Non-accrual	48,106	50,150
Current	4,392,278	4,345,516
Loans and leases, net of unearned income	4,446,701	4,404,548
Real estate – commercial mortgage
>90 Days Past Due and Accruing	4,113	1,765
Non-accrual	33,166	30,388
Current	6,651,042	6,388,426
Loans and leases, net of unearned income	6,700,776	6,434,285
Commercial - secured
>90 Days Past Due and Accruing	986	1,068
Non-accrual	47,506	49,299
Current	4,145,323	4,168,448
Loans and leases, net of unearned income	4,198,173	4,224,980
Commercial - unsecured
>90 Days Past Due and Accruing	399	51
Non-accrual	600	851
Current	246,955	177,068
Loans and leases, net of unearned income	248,528	179,568
Real estate – home equity
>90 Days Past Due and Accruing	3,564	3,061
Non-accrual	7,004	6,708
Current	1,292,035	1,431,666
Loans and leases, net of unearned income	1,314,944	1,452,137
Real estate – residential mortgage
>90 Days Past Due and Accruing	5,735	4,433
Non-accrual	16,676	14,668
Current	2,584,763	2,202,955
Loans and leases, net of unearned income	2,641,465	2,251,044
Real estate – construction
>90 Days Past Due and Accruing	688	0
Non-accrual	3,618	7,390
Current	964,158	906,720
Loans and leases, net of unearned income	971,079	916,599
Construction - commercial residential
>90 Days Past Due and Accruing	64	0
Non-accrual	3,414	6,881
Current	102,868	108,502
Loans and leases, net of unearned income	107,166	117,872
Construction - commercial
>90 Days Past Due and Accruing	0	0
Non-accrual	19	19
Current	768,641	726,707
Loans and leases, net of unearned income	769,560	726,726
Construction - other
>90 Days Past Due and Accruing	624	0
Non-accrual	185	490
Current	92,649	71,511
Loans and leases, net of unearned income	94,353	72,001
Consumer
>90 Days Past Due and Accruing	458	409
Non-accrual	0	0
Current	457,556	415,034
Loans and leases, net of unearned income	463,164	419,186
Consumer - direct
>90 Days Past Due and Accruing	190	66
Non-accrual	0	0
Current	63,582	55,629
Loans and leases, net of unearned income	64,237	56,033
Consumer - indirect
>90 Days Past Due and Accruing	268	343
Non-accrual	0	0
Current	393,974	359,405
Loans and leases, net of unearned income	398,927	363,153
Leasing and other and overdrafts
>90 Days Past Due and Accruing	114	319
Non-accrual	16,528	19,268
Current	278,743	267,112
Loans and leases, net of unearned income	299,397	288,001
30-59 Days Past Due
Total Past Due	56,326	53,640
30-59 Days Past Due | Commercial – industrial, financial and agricultural
Total Past Due	2,302	6,825
30-59 Days Past Due | Real estate – commercial mortgage
Total Past Due	10,912	12,206
30-59 Days Past Due | Commercial - secured
Total Past Due	2,062	5,227
30-59 Days Past Due | Commercial - unsecured
Total Past Due	240	1,598
30-59 Days Past Due | Real estate – home equity
Total Past Due	9,635	7,144
30-59 Days Past Due | Real estate – residential mortgage
Total Past Due	26,982	20,796
30-59 Days Past Due | Real estate – construction
Total Past Due	1,715	2,489
30-59 Days Past Due | Construction - commercial residential
Total Past Due	820	2,489
30-59 Days Past Due | Construction - commercial
Total Past Due	0	0
30-59 Days Past Due | Construction - other
Total Past Due	895	0
30-59 Days Past Due | Consumer
Total Past Due	4,228	3,175
30-59 Days Past Due | Consumer - direct
Total Past Due	278	267
30-59 Days Past Due | Consumer - indirect
Total Past Due	3,950	2,908
30-59 Days Past Due | Leasing and other and overdrafts
Total Past Due	552	1,005
60-89 Days Past Due
Total Past Due	19,470	15,053
60-89 Days Past Due | Commercial – industrial, financial and agricultural
Total Past Due	2,630	938
60-89 Days Past Due | Real estate – commercial mortgage
Total Past Due	1,543	1,500
60-89 Days Past Due | Commercial - secured
Total Past Due	2,296	938
60-89 Days Past Due | Commercial - unsecured
Total Past Due	334	0
60-89 Days Past Due | Real estate – home equity
Total Past Due	2,706	3,558
60-89 Days Past Due | Real estate – residential mortgage
Total Past Due	7,309	8,192
60-89 Days Past Due | Real estate – construction
Total Past Due	900	0
60-89 Days Past Due | Construction - commercial residential
Total Past Due	0	0
60-89 Days Past Due | Construction - commercial
Total Past Due	900	0
60-89 Days Past Due | Construction - other
Total Past Due	0	0
60-89 Days Past Due | Consumer
Total Past Due	922	568
60-89 Days Past Due | Consumer - direct
Total Past Due	187	71
60-89 Days Past Due | Consumer - indirect
Total Past Due	735	497
60-89 Days Past Due | Leasing and other and overdrafts
Total Past Due	$ 3,460	$ 297