Loans and Allowance for Credit Losses Past Due Loan Status and Non-Accrual Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 183,478	$ 196,741
≥ 90 Days Past Due and Accruing	15,992	15,291
Non- accrual	111,742	129,523
Current	13,971,681	13,641,861
Loans, net of unearned income	14,155,159	13,838,602	$ 13,244,230
Real-estate commercial mortage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	45,805	48,951
≥ 90 Days Past Due and Accruing	192	439
Non- accrual	35,512	40,731
Current	5,589,542	5,413,379
Loans, net of unearned income	5,635,347	5,462,330	5,237,800
Commercial - Secured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	49,411	51,620
≥ 90 Days Past Due and Accruing	2,997	1,853
Non- accrual	34,675	41,498
Current	3,894,330	3,874,493
Loans, net of unearned income	3,943,741	3,926,113
Commercial - unsecured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,645	1,313
≥ 90 Days Past Due and Accruing	367	19
Non- accrual	863	701
Current	153,791	161,536
Loans, net of unearned income	155,436	162,849
Commercial - industrial, financial, and agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	51,056	52,933
≥ 90 Days Past Due and Accruing	3,364	1,872
Non- accrual	35,538	42,199
Current	4,048,121	4,036,029
Loans, net of unearned income	4,099,177	4,088,962	3,806,699
Real-estate - home equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	24,224	23,666
≥ 90 Days Past Due and Accruing	3,470	3,473
Non- accrual	10,703	11,210
Current	1,623,095	1,660,773
Loans, net of unearned income	1,647,319	1,684,439	1,689,688
Real-estate - residential mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	39,048	46,789
≥ 90 Days Past Due and Accruing	4,461	6,570
Non- accrual	20,569	21,914
Current	1,408,244	1,329,371
Loans, net of unearned income	1,447,292	1,376,160	1,369,103
Construction - Commercial Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	9,040	13,073
≥ 90 Days Past Due and Accruing	0	0
Non- accrual	8,499	11,213
Current	174,627	166,230
Loans, net of unearned income	183,667	179,303
Construction - Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,897	864
≥ 90 Days Past Due and Accruing	1,777	0
Non- accrual	504	638
Current	599,216	559,127
Loans, net of unearned income	604,113	559,991
Construction other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,515	697
≥ 90 Days Past Due and Accruing	682	416
Non- accrual	417	193
Current	63,404	59,997
Loans, net of unearned income	65,919	60,694
Real-estate - construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	16,452	14,634
≥ 90 Days Past Due and Accruing	2,459	416
Non- accrual	9,420	12,044
Current	837,247	785,354
Loans, net of unearned income	853,699	799,988	731,925
Consumer - direct [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,555	4,457
≥ 90 Days Past Due and Accruing	1,695	2,203
Non- accrual	0	0
Current	92,906	94,262
Loans, net of unearned income	96,461	98,719
Consumer - Indirect [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,317	3,046
≥ 90 Days Past Due and Accruing	193	237
Non- accrual	0	0
Current	179,293	166,823
Loans, net of unearned income	181,610	169,869
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,872	7,503
≥ 90 Days Past Due and Accruing	1,888	2,440
Non- accrual	0	0
Current	272,199	261,085
Loans, net of unearned income	278,071	268,588	272,494
Leasing and other and overdrafts [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,021	2,265
≥ 90 Days Past Due and Accruing	158	81
Non- accrual	0	1,425
Current	193,233	155,870
Loans, net of unearned income	194,254	158,135	$ 136,521
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	36,874	40,194
Financing Receivables, 30 to 59 Days Past Due [Member] | Real-estate commercial mortage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	7,813	6,469
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial - Secured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,532	5,654
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial - unsecured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	372	510
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial - industrial, financial, and agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,904	6,164
Financing Receivables, 30 to 59 Days Past Due [Member] | Real-estate - home equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	7,600	6,438
Financing Receivables, 30 to 59 Days Past Due [Member] | Real-estate - residential mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	10,356	15,141
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction - Commercial Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	1,366
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction - Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,482	50
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,416	88
Financing Receivables, 30 to 59 Days Past Due [Member] | Real-estate - construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,898	1,504
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer - direct [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,169	1,687
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer - Indirect [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,734	2,308
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,903	3,995
Financing Receivables, 30 to 59 Days Past Due [Member] | Leasing and other and overdrafts [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	400	483
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	18,870	11,733
Financing Receivables, 60 to 89 Days Past Due [Member] | Real-estate commercial mortage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,288	1,312
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial - Secured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	7,207	2,615
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial - unsecured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	43	83
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial - industrial, financial, and agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	7,250	2,698
Financing Receivables, 60 to 89 Days Past Due [Member] | Real-estate - home equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,451	2,545
Financing Receivables, 60 to 89 Days Past Due [Member] | Real-estate - residential mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,662	3,164
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction - Commercial Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	541	494
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction - Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,134	176
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Real-estate - construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,675	670
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer - direct [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	691	567
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer - Indirect [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	390	501
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,081	1,068
Financing Receivables, 60 to 89 Days Past Due [Member] | Leasing and other and overdrafts [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	463	276
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	127,734	144,814
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real-estate commercial mortage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	35,704	41,170
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial - Secured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	37,672	43,351
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial - unsecured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,230	720
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial - industrial, financial, and agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	38,902	44,071
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real-estate - home equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	14,173	14,683
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real-estate - residential mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	25,030	28,484
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction - Commercial Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	8,499	11,213
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction - Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,281	638
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,099	609
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real-estate - construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	11,879	12,460
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer - direct [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,695	2,203
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer - Indirect [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	193	237
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,888	2,440
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Leasing and other and overdrafts [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 158	$ 1,506