Loans and Allowance for Credit Losses Summary of Delinquency and Non-Performing Status by Portfolio Segment (Details) $ in Thousands		6 Months Ended
		Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jun. 30, 2014 USD ($)
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		$ 13,244,230	$ 13,111,716	$ 12,839,511
Real-estate - home equity [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		1,689,688	1,736,688	1,730,497
Real-estate - residential mortgage [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		1,369,103	1,377,068	1,361,976
Construction other [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		56,561	59,512
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		272,494	265,431	280,557
Consumer - direct [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		109,197	109,323
Consumer - Indirect [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		163,297	156,108
Leasing and other and overdrafts [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		136,521	119,206	$ 102,008
Real Estate, Home Equity, Construction, Other, Consumer and Leasing [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		3,524,367	3,557,905
Commercial Loans, Commerical Mortgages, Constructions Loans [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		$ 9,719,863	$ 9,553,811
Loans And Leases Receivable Percentage Of Loans Within Delinquecy Category By Total Non Risk Rated Loans		100.00%	100.00%
Performing Financing Receivable [Member] | Real-estate - home equity [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		$ 1,665,771	$ 1,711,017
Performing Financing Receivable [Member] | Real-estate - residential mortgage [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		1,316,650	1,321,139
Performing Financing Receivable [Member] | Construction other [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		55,864	59,180
Performing Financing Receivable [Member] | Consumer [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		265,186	257,376
Performing Financing Receivable [Member] | Consumer - direct [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		103,985	104,018
Performing Financing Receivable [Member] | Consumer - Indirect [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		161,201	153,358
Performing Financing Receivable [Member] | Leasing and other and overdrafts [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		135,895	118,550
Performing Financing Receivable [Member] | Real Estate, Home Equity, Construction, Other, Consumer and Leasing [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income		$ 3,439,366	$ 3,467,262
Performing Financing Receivable [Member] | Commercial Loans, Commerical Mortgages, Constructions Loans [Member]
Financing Receivable, Impaired [Line Items]
Loans And Leases Receivable Percentage Of Loans Within Delinquecy Category By Total Non Risk Rated Loans		97.60%	97.50%
Delinquent [Member] | Real-estate - home equity [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[1]	$ 9,285	$ 10,931
Delinquent [Member] | Real-estate - residential mortgage [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[1]	20,891	26,934
Delinquent [Member] | Construction other [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[1]	0	0
Delinquent [Member] | Consumer [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[1]	4,725	5,465
Delinquent [Member] | Consumer - direct [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[1]	2,886	2,891
Delinquent [Member] | Consumer - Indirect [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[1]	1,839	2,574
Delinquent [Member] | Leasing and other and overdrafts [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[1]	553	523
Delinquent [Member] | Real Estate, Home Equity, Construction, Other, Consumer and Leasing [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[1]	$ 35,454	$ 43,853
Delinquent [Member] | Commercial Loans, Commerical Mortgages, Constructions Loans [Member]
Financing Receivable, Impaired [Line Items]
Loans And Leases Receivable Percentage Of Loans Within Delinquecy Category By Total Non Risk Rated Loans	[1]	1.00%	1.20%
Nonperforming Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Days past due		90
Nonperforming Financing Receivable [Member] | Real-estate - home equity [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[2]	$ 14,632	$ 14,740
Nonperforming Financing Receivable [Member] | Real-estate - residential mortgage [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[2]	31,562	28,995
Nonperforming Financing Receivable [Member] | Construction other [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[2]	697	332
Nonperforming Financing Receivable [Member] | Consumer [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[2]	2,583	2,590
Nonperforming Financing Receivable [Member] | Consumer - direct [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[2]	2,326	2,414
Nonperforming Financing Receivable [Member] | Consumer - Indirect [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[2]	257	176
Nonperforming Financing Receivable [Member] | Leasing and other and overdrafts [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[2]	73	133
Nonperforming Financing Receivable [Member] | Real Estate, Home Equity, Construction, Other, Consumer and Leasing [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	[2]	$ 49,547	$ 46,790
Nonperforming Financing Receivable [Member] | Commercial Loans, Commerical Mortgages, Constructions Loans [Member]
Financing Receivable, Impaired [Line Items]
Loans And Leases Receivable Percentage Of Loans Within Delinquecy Category By Total Non Risk Rated Loans	[2]	1.40%	1.30%
Minimum [Member] | Delinquent [Member]
Financing Receivable, Impaired [Line Items]
Days past due		31
Maximum [Member] | Delinquent [Member]
Financing Receivable, Impaired [Line Items]
Days past due		89

[1] )Includes all accruing loans 31 days to 89 days past due

[2] Includes all accruing loans 90 days or more past due and all non-accrual loans.