Loans and Allowance for Credit Losses Summary of Delinquency and Non-Performing Status by Portfolio Segment (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Loans, net of unearned income	$ 13,838,602	$ 13,111,716
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	$ 1,684,439	1,736,688
Real estate – residential mortgage
Loans, net of unearned income	1,376,160	1,377,068
Construction - other
Loans, net of unearned income	60,694	59,512
Consumer - direct
Loans, net of unearned income	98,719	109,323
Consumer - indirect
Loans, net of unearned income	169,869	156,108
Consumer
Loans, net of unearned income	268,588	265,431
Leasing and other and overdrafts
Loans, net of unearned income	158,135	119,206
Commercial Loans, Commerical Mortgages, Constructions Loans
Loans, net of unearned income	$ 3,548,016	$ 3,557,905
Ratio of nonperforming loans to all loans	100.00%	100.00%
Performing | Real estate – home equity
Loans, net of unearned income	$ 1,660,773	$ 1,711,017
Performing | Real estate – residential mortgage
Loans, net of unearned income	1,329,371	1,321,139
Performing | Construction - other
Loans, net of unearned income	59,997	59,180
Performing | Consumer - direct
Loans, net of unearned income	94,262	104,018
Performing | Consumer - indirect
Loans, net of unearned income	166,823	153,358
Performing | Consumer
Loans, net of unearned income	261,085	257,376
Performing | Leasing and other and overdrafts
Loans, net of unearned income	155,870	118,550
Performing | Commercial Loans, Commerical Mortgages, Constructions Loans
Loans, net of unearned income	$ 3,467,096	$ 3,467,262
Ratio of nonperforming loans to all loans	97.70%	97.50%
Delinquent | Real estate – home equity
Loans, net of unearned income	$ 8,983	$ 10,931
Delinquent | Real estate – residential mortgage
Loans, net of unearned income	18,305	26,934
Delinquent | Construction - other
Loans, net of unearned income	88	0
Delinquent | Consumer - direct
Loans, net of unearned income	2,254	2,891
Delinquent | Consumer - indirect
Loans, net of unearned income	2,809	2,574
Delinquent | Consumer
Loans, net of unearned income	5,063	5,465
Delinquent | Leasing and other and overdrafts
Loans, net of unearned income	759	523
Delinquent | Commercial Loans, Commerical Mortgages, Constructions Loans
Loans, net of unearned income	$ 33,198	$ 43,853
Ratio of nonperforming loans to all loans	1.00%	1.20%
Nonperforming | Real estate – home equity
Loans, net of unearned income	$ 14,683	$ 14,740
Nonperforming | Real estate – residential mortgage
Loans, net of unearned income	28,484	28,995
Nonperforming | Construction - other
Loans, net of unearned income	609	332
Nonperforming | Consumer - direct
Loans, net of unearned income	2,203	2,414
Nonperforming | Consumer - indirect
Loans, net of unearned income	237	176
Nonperforming | Consumer
Loans, net of unearned income	2,440	2,590
Nonperforming | Leasing and other and overdrafts
Loans, net of unearned income	1,506	133
Nonperforming | Commercial Loans, Commerical Mortgages, Constructions Loans
Loans, net of unearned income	$ 47,722	$ 46,790
Ratio of nonperforming loans to all loans	1.30%	1.30%