Loans and Allowance for Credit Losses Summary of Delinquency and Non-Performing Status by Portfolio Segment (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Loans, net of unearned income	$ 13,111,716		$ 12,782,220
Period for which change in loans evaluated individually for impairment	90
Minimum
Days outstanding	30
Maximum
Days outstanding	89
Real estate – home equity
Loans, net of unearned income	1,736,688		1,764,197
Real estate – residential mortgage
Loans, net of unearned income	1,377,068		1,337,380
Construction - other
Loans, net of unearned income	59,512		68,806
Consumer - direct
Loans, net of unearned income	109,323		132,643
Consumer - indirect
Loans, net of unearned income	156,108		150,481
Consumer
Loans, net of unearned income	265,431		283,124
Leasing and other and overdrafts
Loans, net of unearned income	119,206		93,505
Commercial Loans, Commerical Mortgages, Constructions Loans
Loans, net of unearned income	3,557,905		3,547,012
Ratio of nonperforming loans to all loans	100.00%		100.00%
Performing | Real estate – home equity
Loans, net of unearned income	1,711,017		1,731,185
Performing | Real estate – residential mortgage
Loans, net of unearned income	1,321,139		1,282,754
Performing | Construction - other
Loans, net of unearned income	59,180		68,258
Performing | Consumer - direct
Loans, net of unearned income	104,018		126,666
Performing | Consumer - indirect
Loans, net of unearned income	153,358		147,017
Performing | Consumer
Loans, net of unearned income	257,376		273,683
Performing | Leasing and other and overdrafts
Loans, net of unearned income	118,550		92,876
Performing | Commercial Loans, Commerical Mortgages, Constructions Loans
Loans, net of unearned income	3,467,262		3,448,756
Ratio of nonperforming loans to all loans	97.50%		97.20%
Delinquent | Real estate – home equity
Loans, net of unearned income	10,931	[1]	16,029	[1]
Delinquent | Real estate – residential mortgage
Loans, net of unearned income	26,934	[1]	23,279	[1]
Delinquent | Construction - other
Loans, net of unearned income	0	[1]	0	[1]
Delinquent | Consumer - direct
Loans, net of unearned income	2,891	[1]	3,586	[1]
Delinquent | Consumer - indirect
Loans, net of unearned income	2,574	[1]	3,312	[1]
Delinquent | Consumer
Loans, net of unearned income	5,465	[1]	6,898	[1]
Delinquent | Leasing and other and overdrafts
Loans, net of unearned income	523	[1]	581	[1]
Delinquent | Commercial Loans, Commerical Mortgages, Constructions Loans
Loans, net of unearned income	43,853	[1]	46,787	[1]
Ratio of nonperforming loans to all loans	1.20%		1.30%
Nonperforming | Real estate – home equity
Loans, net of unearned income	14,740	[2]	16,983	[2]
Nonperforming | Real estate – residential mortgage
Loans, net of unearned income	28,995	[2]	31,347	[2]
Nonperforming | Construction - other
Loans, net of unearned income	332	[2]	548	[2]
Nonperforming | Consumer - direct
Loans, net of unearned income	2,414	[2]	2,391	[2]
Nonperforming | Consumer - indirect
Loans, net of unearned income	176	[2]	152	[2]
Nonperforming | Consumer
Loans, net of unearned income	2,590	[2]	2,543	[2]
Nonperforming | Leasing and other and overdrafts
Loans, net of unearned income	133	[2]	48	[2]
Nonperforming | Commercial Loans, Commerical Mortgages, Constructions Loans
Loans, net of unearned income	$ 46,790	[2]	$ 51,469	[2]
Ratio of nonperforming loans to all loans	1.30%		1.50%

[1] 1)Includes all accruing loans 30 days to 89 days past due

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