Loans and Allowance for Credit Losses Past Due Loan Status and Non-Accrual Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 228,091	$ 208,371
≥ 90 Days Past Due and Accruing	14,598	11,106
Non- accrual	133,118	128,572
Current	16,140,367	15,957,429
Loans and leases, net of unearned income	16,368,458	16,165,800	$ 15,792,969
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	67,112	53,640
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	13,263	15,053
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	147,716	139,678
Real-estate - commercial mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	62,529	45,859
≥ 90 Days Past Due and Accruing	637	1,765
Non- accrual	43,213	30,388
Current	6,435,444	6,388,426
Loans and leases, net of unearned income	6,497,973	6,434,285	6,304,475
Real-estate - commercial mortgage | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	16,620	12,206
Real-estate - commercial mortgage | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,059	1,500
Real-estate - commercial mortgage | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	43,850	32,153
Commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	56,939	56,532
≥ 90 Days Past Due and Accruing	1,422	1,068
Non- accrual	45,114	49,299
Current	4,132,657	4,168,448
Loans and leases, net of unearned income	4,189,596	4,224,980
Commercial | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	8,480	5,227
Commercial | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,923	938
Commercial | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	46,536	50,367
Commercial - unsecured
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,451	2,500
≥ 90 Days Past Due and Accruing	0	51
Non- accrual	723	851
Current	174,201	177,068
Loans and leases, net of unearned income	175,652	179,568
Commercial - unsecured | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	592	1,598
Commercial - unsecured | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	136	0
Commercial - unsecured | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	723	902
Commercial - industrial, financial and agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	58,390	59,032
≥ 90 Days Past Due and Accruing	1,422	1,119
Non- accrual	45,837	50,150
Current	4,306,858	4,345,516
Loans and leases, net of unearned income	4,365,248	4,404,548	4,264,602
Commercial - industrial, financial and agricultural | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	9,072	6,825
Commercial - industrial, financial and agricultural | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,059	938
Commercial - industrial, financial and agricultural | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	47,259	51,269
Real-estate - home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	23,630	20,471
≥ 90 Days Past Due and Accruing	4,803	3,061
Non- accrual	7,193	6,708
Current	1,363,344	1,431,666
Loans and leases, net of unearned income	1,386,974	1,452,137	1,491,395
Real-estate - home equity | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	9,370	7,144
Real-estate - home equity | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,264	3,558
Real-estate - home equity | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	11,996	9,769
Real estate - residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	53,534	48,089
≥ 90 Days Past Due and Accruing	6,708	4,433
Non- accrual	14,950	14,668
Current	2,398,432	2,202,955
Loans and leases, net of unearned income	2,451,966	2,251,044	2,094,530
Real estate - residential mortgage | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	26,135	20,796
Real estate - residential mortgage | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,741	8,192
Real estate - residential mortgage | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	21,658	19,101
Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,959	9,370
≥ 90 Days Past Due and Accruing	0	0
Non- accrual	3,959	6,881
Current	112,250	108,502
Loans and leases, net of unearned income	116,209	117,872
Construction | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	2,489
Construction | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Construction | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,959	6,881
Construction - commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,380	19
≥ 90 Days Past Due and Accruing	466	0
Non- accrual	19	19
Current	728,104	726,707
Loans and leases, net of unearned income	729,484	726,726
Construction - commercial | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	895	0
Construction - commercial | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Construction - commercial | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	485	19
Construction - other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	738	490
≥ 90 Days Past Due and Accruing	0	0
Non- accrual	189	490
Current	76,116	71,511
Loans and leases, net of unearned income	76,854	72,001
Construction - other | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	549	0
Construction - other | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Construction - other | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	189	490
Real estate - construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,077	9,879
≥ 90 Days Past Due and Accruing	466	0
Non- accrual	4,167	7,390
Current	916,470	906,720
Loans and leases, net of unearned income	922,547	916,599	990,705
Real estate - construction | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,444	2,489
Real estate - construction | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Real estate - construction | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,633	7,390
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	418	404
≥ 90 Days Past Due and Accruing	123	66
Non- accrual	0	0
Current	58,295	55,629
Loans and leases, net of unearned income	58,713	56,033
Consumer | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	205	267
Consumer | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	90	71
Consumer | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	123	66
Consumer - indirect
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,767	3,748
≥ 90 Days Past Due and Accruing	259	343
Non- accrual	0	0
Current	390,394	359,405
Loans and leases, net of unearned income	394,161	363,153
Consumer - indirect | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,901	2,908
Consumer - indirect | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	607	497
Consumer - indirect | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	259	343
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,185	4,152
≥ 90 Days Past Due and Accruing	382	409
Non- accrual	0	0
Current	448,689	415,034
Loans and leases, net of unearned income	452,874	419,186	360,315
Consumer | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,106	3,175
Consumer | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	697	568
Consumer | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	382	409
Equipment lease financing, other and overdrafts
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	19,746	20,889
≥ 90 Days Past Due and Accruing	180	319
Non- accrual	17,758	19,268
Current	271,130	267,112
Loans and leases, net of unearned income	290,876	288,001	$ 286,947
Equipment lease financing, other and overdrafts | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,365	1,005
Equipment lease financing, other and overdrafts | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	443	297
Equipment lease financing, other and overdrafts | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 17,938	$ 19,587