Loans and Allowance for Credit Losses Past Due Loan Status and Non-Accrual Loans by Portfolio Segment (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
31-59 Days Past Due	$ 54,071	$ 60,774
60-89 Days Past Due	17,339	16,893
>90 Days Past Due and Accruing	21,225	20,524
Non-accrual	133,705	133,753
Total >90 Days	154,930	154,277
Total Past Due	226,340	231,944
Current	12,507,452	12,550,276
Loans, net of unearned income	12,733,792	12,782,220	12,377,288
Real-estate commercial mortage [Member]
31-59 Days Past Due	13,290	15,474
60-89 Days Past Due	4,633	4,009
>90 Days Past Due and Accruing	3,492	3,502
Non-accrual	42,384	40,566
Total >90 Days	45,876	44,068
Total Past Due	63,799	63,551
Current	5,073,655	5,038,371
Loans, net of unearned income	5,137,454	5,101,922	4,729,930
Commercial - industrial, financial, and agricultural
31-59 Days Past Due	9,674	9,248
60-89 Days Past Due	2,161	1,490
>90 Days Past Due and Accruing	312	1,311
Non-accrual	38,518	36,710
Total >90 Days	38,830	38,021
Total Past Due	50,665	48,759
Current	3,523,465	3,579,661
Loans, net of unearned income	3,574,130	3,628,420	3,658,483
Commercial - Secured [Member]
31-59 Days Past Due	9,370	8,916
60-89 Days Past Due	1,886	1,365
>90 Days Past Due and Accruing	308	1,311
Non-accrual	37,958	35,774
Total >90 Days	38,266	37,085
Total Past Due	49,522	47,366
Current	3,325,519	3,356,797
Loans, net of unearned income	3,375,041	3,404,163
Commercial - unsecured [Member]
31-59 Days Past Due	304	332
60-89 Days Past Due	275	125
>90 Days Past Due and Accruing	4	0
Non-accrual	560	936
Total >90 Days	564	936
Total Past Due	1,143	1,393
Current	197,946	222,864
Loans, net of unearned income	199,089	224,257
Real-estate - home equity [Member]
31-59 Days Past Due	9,347	13,555
60-89 Days Past Due	2,631	2,474
>90 Days Past Due and Accruing	5,540	3,711
Non-accrual	11,548	13,272
Total >90 Days	17,088	16,983
Total Past Due	29,066	33,012
Current	1,711,430	1,731,185
Loans, net of unearned income	1,740,496	1,764,197	1,689,446
Real-estate - residential mortgage [Member]
31-59 Days Past Due	14,682	16,969
60-89 Days Past Due	5,624	6,310
>90 Days Past Due and Accruing	7,986	9,065
Non-accrual	21,319	22,282
Total >90 Days	29,305	31,347
Total Past Due	49,611	54,626
Current	1,281,854	1,282,754
Loans, net of unearned income	1,331,465	1,337,380	1,303,454
Construction other [Member]
31-59 Days Past Due	940	0
60-89 Days Past Due	0	0
>90 Days Past Due and Accruing	0	0
Non-accrual	544	548
Total >90 Days	544	548
Total Past Due	1,484	548
Current	70,096	68,258
Loans, net of unearned income	71,580	68,806
Real-estate - construction
31-59 Days Past Due	2,292	14
60-89 Days Past Due	228	645
>90 Days Past Due and Accruing	823	346
Non-accrual	19,935	20,921
Total >90 Days	20,758	21,267
Total Past Due	23,278	21,926
Current	560,939	551,746
Loans, net of unearned income	584,217	573,672	597,597
Construction - Commercial Residential [Member]
31-59 Days Past Due	1,352	0
60-89 Days Past Due	228	645
>90 Days Past Due and Accruing	796	346
Non-accrual	17,238	18,202
Total >90 Days	18,034	18,548
Total Past Due	19,614	19,193
Current	209,927	216,176
Loans, net of unearned income	229,541	235,369
Construction - Commercial [Member]
31-59 Days Past Due	0	14
60-89 Days Past Due	0	0
>90 Days Past Due and Accruing	27	0
Non-accrual	2,153	2,171
Total >90 Days	2,180	2,171
Total Past Due	2,180	2,185
Current	280,916	267,312
Loans, net of unearned income	283,096	269,497
Total Consumer
31-59 Days Past Due	4,455	4,955
60-89 Days Past Due	1,599	1,943
>90 Days Past Due and Accruing	2,998	2,541
Non-accrual	1	2
Total >90 Days	2,999	2,543
Total Past Due	9,053	9,441
Current	260,968	273,683
Loans, net of unearned income	270,021	283,124	309,138
Consumer - direct [Member]
31-59 Days Past Due	2,495	2,091
60-89 Days Past Due	1,139	1,495
>90 Days Past Due and Accruing	2,872	2,391
Non-accrual	0	0
Total >90 Days	2,872	2,391
Total Past Due	6,506	5,977
Current	116,748	126,666
Loans, net of unearned income	123,254	132,643
Consumer - Indirect [Member]
31-59 Days Past Due	1,960	2,864
60-89 Days Past Due	460	448
>90 Days Past Due and Accruing	126	150
Non-accrual	1	2
Total >90 Days	127	152
Total Past Due	2,547	3,464
Current	144,220	147,017
Loans, net of unearned income	146,767	150,481
Leasing and other and overdrafts [Member]
31-59 Days Past Due	331	559
60-89 Days Past Due	463	22
>90 Days Past Due and Accruing	74	48
Non-accrual	0	0
Total >90 Days	74	48
Total Past Due	868	629
Current	95,141	92,876
Loans, net of unearned income	96,009	93,505	89,240
Commercial Loans, Commerical Mortgages, Constructions Loans [Member]
Loans, net of unearned income	3,509,571	3,547,012
Loans And Leases Receivable Percentage Of Loans Within Delinquecy Category By Total Non Risk Rated Loans	100.00%	100.00%
Delinquent [Member] | Real-estate - home equity [Member]
Loans, net of unearned income	11,978	16,029
Delinquent [Member] | Real-estate - residential mortgage [Member]
Loans, net of unearned income	20,306	23,279
Delinquent [Member] | Construction other [Member]
Loans, net of unearned income	940	0
Delinquent [Member] | Total Consumer
Loans, net of unearned income	6,054	6,898
Delinquent [Member] | Consumer - direct [Member]
Loans, net of unearned income	3,634	3,586
Delinquent [Member] | Consumer - Indirect [Member]
Loans, net of unearned income	2,420	3,312
Delinquent [Member] | Leasing and other and overdrafts [Member]
Loans, net of unearned income	794	581
Delinquent [Member] | Commercial Loans, Commerical Mortgages, Constructions Loans [Member]
Loans, net of unearned income	40,072	46,787
Loans And Leases Receivable Percentage Of Loans Within Delinquecy Category By Total Non Risk Rated Loans	1.20%	1.30%
Nonperforming Financing Receivable [Member] | Real-estate - home equity [Member]
Loans, net of unearned income	17,088	16,983
Nonperforming Financing Receivable [Member] | Real-estate - residential mortgage [Member]
Loans, net of unearned income	29,305	31,347
Nonperforming Financing Receivable [Member] | Construction other [Member]
Loans, net of unearned income	544	548
Nonperforming Financing Receivable [Member] | Total Consumer
Loans, net of unearned income	2,999	2,543
Nonperforming Financing Receivable [Member] | Consumer - direct [Member]
Loans, net of unearned income	2,872	2,391
Nonperforming Financing Receivable [Member] | Consumer - Indirect [Member]
Loans, net of unearned income	127	152
Nonperforming Financing Receivable [Member] | Leasing and other and overdrafts [Member]
Loans, net of unearned income	74	48
Nonperforming Financing Receivable [Member] | Commercial Loans, Commerical Mortgages, Constructions Loans [Member]
Loans, net of unearned income	50,010	51,469
Loans And Leases Receivable Percentage Of Loans Within Delinquecy Category By Total Non Risk Rated Loans	1.40%	1.50%
Performing Financing Receivable [Member] | Real-estate - home equity [Member]
Loans, net of unearned income	1,711,430	1,731,185
Performing Financing Receivable [Member] | Real-estate - residential mortgage [Member]
Loans, net of unearned income	1,281,854	1,282,754
Performing Financing Receivable [Member] | Construction other [Member]
Loans, net of unearned income	70,096	68,258
Performing Financing Receivable [Member] | Total Consumer
Loans, net of unearned income	260,968	273,683
Performing Financing Receivable [Member] | Consumer - direct [Member]
Loans, net of unearned income	116,748	126,666
Performing Financing Receivable [Member] | Consumer - Indirect [Member]
Loans, net of unearned income	144,220	147,017
Performing Financing Receivable [Member] | Leasing and other and overdrafts [Member]
Loans, net of unearned income	95,141	92,876
Performing Financing Receivable [Member] | Commercial Loans, Commerical Mortgages, Constructions Loans [Member]
Loans, net of unearned income	$ 3,419,489	$ 3,448,756
Loans And Leases Receivable Percentage Of Loans Within Delinquecy Category By Total Non Risk Rated Loans	97.40%	97.20%