Loans and Allowance for Credit Losses Past Due Loan Status and Non-Accrual Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 183,730	$ 186,787
≥ 90 Days Past Due and Accruing	14,268	11,505
Non- accrual	117,264	120,133
Current	14,779,447	14,512,485
Loans, net of unearned income	14,963,177	14,699,272	$ 13,870,701
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	40,539	41,938
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	11,659	13,211
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	131,532	131,638
Real-estate - commercial mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	47,574	47,195
≥ 90 Days Past Due and Accruing	910	383
Non- accrual	35,803	38,936
Current	6,070,959	5,971,387
Loans, net of unearned income	6,118,533	6,018,582	5,558,108
Real-estate - commercial mortgage | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	9,890	6,254
Real-estate - commercial mortgage | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	971	1,622
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	36,713	39,319
Commercial - secured
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	50,304	51,824
≥ 90 Days Past Due and Accruing	2,511	959
Non- accrual	40,084	41,589
Current	3,980,613	3,881,728
Loans, net of unearned income	4,030,917	3,933,552
Commercial - secured | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,530	6,660
Commercial - secured | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,179	2,616
Commercial - secured | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	42,595	42,548
Commercial - unsecured
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,594	1,845
≥ 90 Days Past Due and Accruing	497	152
Non- accrual	734	760
Current	135,298	152,089
Loans, net of unearned income	136,892	153,934
Commercial - unsecured | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	309	898
Commercial - unsecured | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	54	35
Commercial - unsecured | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,231	912
Commercial - industrial, financial and agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	51,898	53,669
≥ 90 Days Past Due and Accruing	3,008	1,111
Non- accrual	40,818	42,349
Current	4,115,911	4,033,817
Loans, net of unearned income	4,167,809	4,087,486	4,035,333
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	4,839	7,558
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	3,233	2,651
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	43,826	43,460
Real-estate - home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	19,527	22,428
≥ 90 Days Past Due and Accruing	2,881	2,543
Non- accrual	9,351	10,611
Current	1,576,374	1,602,687
Loans, net of unearned income	1,595,901	1,625,115	1,659,481
Real-estate - home equity | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,181	6,596
Real-estate - home equity | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,114	2,678
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	12,232	13,154
Real-estate - residential mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	40,665	43,999
≥ 90 Days Past Due and Accruing	5,790	5,224
Non- accrual	17,807	18,431
Current	1,624,477	1,557,995
Loans, net of unearned income	1,665,142	1,601,994	1,377,459
Real-estate - residential mortgage | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	12,829	15,600
Real-estate - residential mortgage | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,239	4,744
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	23,597	23,655
Construction - commercial residential
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	14,121	8,595
≥ 90 Days Past Due and Accruing	65	36
Non- accrual	11,705	8,275
Current	137,192	133,594
Loans, net of unearned income	151,313	142,189
Construction - commercial residential | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,550	233
Construction - commercial residential | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	801	51
Construction - commercial residential | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	11,770	8,311
Construction - commercial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,372	1,178
≥ 90 Days Past Due and Accruing	0	0
Non- accrual	684	435
Current	682,756	643,312
Loans, net of unearned income	685,128	644,490
Construction - commercial | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,546	743
Construction - commercial | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	142	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	684	435
Construction - other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,096	1,096
≥ 90 Days Past Due and Accruing	0	0
Non- accrual	1,096	1,096
Current	45,446	55,874
Loans, net of unearned income	46,542	56,970
Construction - other | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	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	1,096	1,096
Real-estate - construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	17,589	10,869
≥ 90 Days Past Due and Accruing	65	36
Non- accrual	13,485	9,806
Current	865,394	832,780
Loans, net of unearned income	882,983	843,649	810,872
Real-estate - construction | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,096	976
Real-estate - construction | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	943	51
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	13,550	9,842
Consumer - direct
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,512	3,315
≥ 90 Days Past Due and Accruing	1,129	1,563
Non- accrual	0	0
Current	84,670	93,572
Loans, net of unearned income	87,182	96,887
Consumer - direct | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	939	1,211
Consumer - direct | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	444	541
Consumer - direct | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,129	1,563
Consumer - indirect
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,102	3,927
≥ 90 Days Past Due and Accruing	47	328
Non- accrual	0	0
Current	199,542	190,656
Loans, net of unearned income	201,644	194,583
Consumer - indirect | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,784	3,200
Consumer - indirect | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	271	399
Consumer - indirect | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	47	328
Consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,614	7,242
≥ 90 Days Past Due and Accruing	1,176	1,891
Non- accrual	0	0
Current	284,212	284,228
Loans, net of unearned income	288,826	291,470	263,221
Consumer | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,723	4,411
Consumer | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	715	940
Consumer | Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,176	1,891
Leasing, other and overdrafts
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,863	1,385
≥ 90 Days Past Due and Accruing	438	317
Non- accrual	0	0
Current	242,120	229,591
Loans, net of unearned income	243,983	230,976	$ 166,227
Leasing, other and overdrafts | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	981	543
Leasing, other and overdrafts | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	444	525
Leasing, 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	$ 438	$ 317