Loans and Allowance for Credit Losses Summary of Delinquency and Non-Performing Status by Portfolio Segment (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Loans, net of unearned income	$ 14,699,272	$ 13,838,602
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	$ 1,625,115	1,684,439
Real estate – residential mortgage
Loans, net of unearned income	1,601,994	1,376,160
Construction - other
Loans, net of unearned income	56,970	60,694
Consumer - direct
Loans, net of unearned income	96,887	98,719
Consumer - indirect:
Loans, net of unearned income	194,583	169,869
Consumer
Loans, net of unearned income	291,470	268,588
Leasing and other and overdrafts
Loans, net of unearned income	230,976	158,135
Commercial Loans, Commerical Mortgages, Constructions Loans
Loans, net of unearned income	$ 3,806,525	$ 3,548,016
Ratio of nonperforming loans to all loans	100.00%	100.00%
Performing | Real estate – home equity
Loans, net of unearned income	$ 1,602,687	$ 1,660,773
Performing | Real estate – residential mortgage
Loans, net of unearned income	1,557,995	1,329,371
Performing | Construction - other
Loans, net of unearned income	55,874	59,997
Performing | Consumer - direct
Loans, net of unearned income	93,572	94,262
Performing | Consumer - indirect:
Loans, net of unearned income	190,656	166,823
Performing | Consumer
Loans, net of unearned income	284,228	261,085
Performing | Leasing and other and overdrafts
Loans, net of unearned income	229,591	155,870
Performing | Commercial Loans, Commerical Mortgages, Constructions Loans
Loans, net of unearned income	$ 3,730,375	$ 3,467,096
Ratio of nonperforming loans to all loans	98.00%	97.70%
Delinquent | Real estate – home equity
Loans, net of unearned income	$ 9,274	$ 8,983
Delinquent | Real estate – residential mortgage
Loans, net of unearned income	20,344	18,305
Delinquent | Construction - other
Loans, net of unearned income	0	88
Delinquent | Consumer - direct
Loans, net of unearned income	1,752	2,254
Delinquent | Consumer - indirect:
Loans, net of unearned income	3,599	2,809
Delinquent | Consumer
Loans, net of unearned income	5,351	5,063
Delinquent | Leasing and other and overdrafts
Loans, net of unearned income	1,068	759
Delinquent | Commercial Loans, Commerical Mortgages, Constructions Loans
Loans, net of unearned income	$ 36,037	$ 33,198
Ratio of nonperforming loans to all loans	0.90%	1.00%
Nonperforming | Real estate – home equity
Loans, net of unearned income	$ 13,154	$ 14,683
Nonperforming | Real estate – residential mortgage
Loans, net of unearned income	23,655	28,484
Nonperforming | Construction - other
Loans, net of unearned income	1,096	609
Nonperforming | Consumer - direct
Loans, net of unearned income	1,563	2,203
Nonperforming | Consumer - indirect:
Loans, net of unearned income	328	237
Nonperforming | Consumer
Loans, net of unearned income	1,891	2,440
Nonperforming | Leasing and other and overdrafts
Loans, net of unearned income	317	1,506
Nonperforming | Commercial Loans, Commerical Mortgages, Constructions Loans
Loans, net of unearned income	$ 40,113	$ 47,722
Ratio of nonperforming loans to all loans	1.10%	1.30%