Loans and Allowance for Credit Losses Past Due Loan Status and Non-Accrual Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 197,934	$ 196,741
≥ 90 Days Past Due and Accruing	14,095	15,291
Non- accrual	124,017	129,523
Current	14,193,304	13,641,861
Loans, net of unearned income	14,391,238	13,838,602	$ 13,536,361
Real-estate commercial mortage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	50,346	48,951
≥ 90 Days Past Due and Accruing	664	439
Non- accrual	38,967	40,731
Current	5,768,569	5,413,379
Loans, net of unearned income	5,818,915	5,462,330	5,339,928
Commercial - Secured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	58,318	51,620
≥ 90 Days Past Due and Accruing	3,023	1,853
Non- accrual	43,304	41,498
Current	3,818,215	3,874,493
Loans, net of unearned income	3,876,533	3,926,113
Commercial - unsecured [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,290	1,313
≥ 90 Days Past Due and Accruing	137	19
Non- accrual	866	701
Current	146,296	161,536
Loans, net of unearned income	147,586	162,849
Commercial - industrial, financial, and agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	59,608	52,933
≥ 90 Days Past Due and Accruing	3,160	1,872
Non- accrual	44,170	42,199
Current	3,964,511	4,036,029
Loans, net of unearned income	4,024,119	4,088,962	3,929,908
Real-estate - home equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	24,764	23,666
≥ 90 Days Past Due and Accruing	3,237	3,473
Non- accrual	11,023	11,210
Current	1,615,657	1,660,773
Loans, net of unearned income	1,640,421	1,684,439	1,693,649
Real-estate - residential mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	41,210	46,789
≥ 90 Days Past Due and Accruing	4,070	6,570
Non- accrual	19,381	21,914
Current	1,501,486	1,329,371
Loans, net of unearned income	1,542,696	1,376,160	1,382,085
Construction - Commercial Residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	11,635	13,073
≥ 90 Days Past Due and Accruing	72	0
Non- accrual	8,930	11,213
Current	150,273	166,230
Loans, net of unearned income	161,908	179,303
Construction - Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,134	864
≥ 90 Days Past Due and Accruing	675	0
Non- accrual	450	638
Current	635,758	559,127
Loans, net of unearned income	636,892	559,991
Construction other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,096	697
≥ 90 Days Past Due and Accruing	0	416
Non- accrual	1,096	193
Current	61,738	59,997
Loans, net of unearned income	62,834	60,694
Real-estate - construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	13,865	14,634
≥ 90 Days Past Due and Accruing	747	416
Non- accrual	10,476	12,044
Current	847,769	785,354
Loans, net of unearned income	861,634	799,988	769,565
Consumer - direct [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,618	4,457
≥ 90 Days Past Due and Accruing	1,943	2,203
Non- accrual	0	0
Current	91,164	94,262
Loans, net of unearned income	94,782	98,719
Consumer - Indirect [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,018	3,046
≥ 90 Days Past Due and Accruing	223	237
Non- accrual	0	0
Current	185,873	166,823
Loans, net of unearned income	188,891	169,869
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,636	7,503
≥ 90 Days Past Due and Accruing	2,166	2,440
Non- accrual	0	0
Current	277,037	261,085
Loans, net of unearned income	283,673	268,588	271,696
Leasing and other and overdrafts [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,505	2,265
≥ 90 Days Past Due and Accruing	51	81
Non- accrual	0	1,425
Current	218,275	155,870
Loans, net of unearned income	219,780	158,135	$ 149,530
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	43,422	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	9,268	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	8,369	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	234	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	8,603	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	6,016	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	12,920	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	2,004	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	0	50
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	0	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	2,004	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	1,147	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	2,466	2,308
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,613	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	998	483
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	16,400	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	1,447	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	3,622	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	53	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	3,675	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	4,488	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	4,839	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	629	494
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction - Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	9	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	638	670
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer - direct [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	528	567
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer - Indirect [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	329	501
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	857	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	456	276
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	138,112	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	39,631	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	46,327	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	1,003	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	47,330	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	14,260	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	23,451	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	9,002	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	1,125	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	1,096	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	11,223	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	1,943	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	223	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	2,166	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	$ 51	$ 1,506