Loans and Allowance for Credit Losses Past Due Loan Status and Non-Accrual Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Financial Receivable, Recorded investment, Past Due [Line Items]
>90 Days Past Due and Accruing	$ 12,867	$ 17,402
Non-accrual	132,154	121,080
Total Past Due	201,715	206,828
Current	13,334,646	12,904,888
Loans, net of unearned income	13,536,361	13,111,716	$ 13,030,405
Real-estate commercial mortage [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
>90 Days Past Due and Accruing	194	800
Non-accrual	48,827	44,437
Total Past Due	57,512	63,313
Current	5,282,416	5,133,842
Loans, net of unearned income	5,339,928	5,197,155	5,156,979
Commercial - industrial, financial, and agricultural [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
>90 Days Past Due and Accruing	1,479	619
Non-accrual	36,553	29,769
Total Past Due	51,872	36,645
Current	3,878,036	3,688,922
Loans, net of unearned income	3,929,908	3,725,567	3,691,262
Commercial - Secured [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
>90 Days Past Due and Accruing	1,414	610
Non-accrual	33,935	28,747
Total Past Due	46,794	35,154
Current	3,736,032	3,529,460
Loans, net of unearned income	3,782,826	3,564,614
Commercial - unsecured [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
>90 Days Past Due and Accruing	65	9
Non-accrual	2,618	1,022
Total Past Due	5,078	1,491
Current	142,004	159,462
Loans, net of unearned income	147,082	160,953
Real-estate - home equity [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
>90 Days Past Due and Accruing	2,883	4,257
Non-accrual	10,224	10,483
Total Past Due	22,176	25,671
Current	1,671,473	1,711,017
Loans, net of unearned income	1,693,649	1,736,688	1,733,036
Real-estate - residential mortgage [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
>90 Days Past Due and Accruing	5,730	8,952
Non-accrual	21,977	20,043
Total Past Due	45,208	55,929
Current	1,336,877	1,321,139
Loans, net of unearned income	1,382,085	1,377,068	1,372,033
Construction - Commercial Residential [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
>90 Days Past Due and Accruing	0	0
Non-accrual	12,073	13,463
Total Past Due	14,136	13,623
Current	176,385	190,047
Loans, net of unearned income	190,521	203,670
Construction - Commercial [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
>90 Days Past Due and Accruing	0	0
Non-accrual	2,220	2,604
Total Past Due	2,485	2,604
Current	519,381	424,815
Loans, net of unearned income	521,866	427,419
Construction other [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
>90 Days Past Due and Accruing	416	51
Non-accrual	280	281
Total Past Due	696	332
Current	56,482	59,180
Loans, net of unearned income	57,178	59,512
Real-estate - construction [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
>90 Days Past Due and Accruing	416	51
Non-accrual	14,573	16,348
Total Past Due	17,317	16,559
Current	752,248	674,042
Loans, net of unearned income	769,565	690,601	687,728
Consumer [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
>90 Days Past Due and Accruing	2,079	2,590
Non-accrual	0	0
Total Past Due	7,080	8,055
Current	264,616	257,376
Loans, net of unearned income	271,696	265,431	278,219
Consumer - direct [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
>90 Days Past Due and Accruing	1,961	2,414
Non-accrual	0	0
Total Past Due	4,658	5,305
Current	98,576	104,018
Loans, net of unearned income	103,234	109,323
Consumer - Indirect [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
>90 Days Past Due and Accruing	118	176
Non-accrual	0	0
Total Past Due	2,422	2,750
Current	166,040	153,358
Loans, net of unearned income	168,462	156,108
Leasing and other and overdrafts [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
>90 Days Past Due and Accruing	86	133
Non-accrual	0	0
Total Past Due	550	656
Current	148,980	118,550
Loans, net of unearned income	149,530	119,206	$ 111,148
Financing Receivables, 30 to 59 Days Past Due [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	40,328	51,177
Financing Receivables, 30 to 59 Days Past Due [Member] | Real-estate commercial mortage [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	7,322	14,399
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial - industrial, financial, and agricultural [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	9,289	5,234
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial - Secured [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	6,909	4,839
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial - unsecured [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	2,380	395
Financing Receivables, 30 to 59 Days Past Due [Member] | Real-estate - home equity [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	6,312	8,048
Financing Receivables, 30 to 59 Days Past Due [Member] | Real-estate - residential mortgage [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	11,499	18,789
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction - Commercial Residential [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	1,832	160
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction - Commercial [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	265	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction other [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Real-estate - construction [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	2,097	160
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	3,360	4,190
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer - direct [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	1,398	2,034
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer - Indirect [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	1,962	2,156
Financing Receivables, 30 to 59 Days Past Due [Member] | Leasing and other and overdrafts [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	449	357
Financing Receivables, 60 to 89 Days Past Due [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	16,366	17,169
Financing Receivables, 60 to 89 Days Past Due [Member] | Real-estate commercial mortage [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	1,169	3,677
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial - industrial, financial, and agricultural [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	4,551	1,023
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial - Secured [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	4,536	958
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial - unsecured [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	15	65
Financing Receivables, 60 to 89 Days Past Due [Member] | Real-estate - home equity [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	2,757	2,883
Financing Receivables, 60 to 89 Days Past Due [Member] | Real-estate - residential mortgage [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	6,002	8,145
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction - Commercial Residential [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	231	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction - Commercial [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction other [Member]
Financial 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]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	231	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	1,641	1,275
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer - direct [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	1,299	857
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer - Indirect [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	342	418
Financing Receivables, 60 to 89 Days Past Due [Member] | Leasing and other and overdrafts [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	15	166
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	145,021	138,482
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real-estate commercial mortage [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	49,021	45,237
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial - industrial, financial, and agricultural [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	38,032	30,388
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial - Secured [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	35,349	29,357
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial - unsecured [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	2,683	1,031
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real-estate - home equity [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	13,107	14,740
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real-estate - residential mortgage [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	27,707	28,995
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction - Commercial Residential [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	12,073	13,463
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction - Commercial [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	2,220	2,604
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction other [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	696	332
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real-estate - construction [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	14,989	16,399
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	2,079	2,590
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer - direct [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	1,961	2,414
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer - Indirect [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	118	176
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Leasing and other and overdrafts [Member]
Financial Receivable, Recorded investment, Past Due [Line Items]
Total Past Due	$ 86	$ 133