Loans and Allowance for Credit Losses Summary of Delinquency and Non-Performing Status by Portfolio Segment (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($) day	Dec. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	$ 14,155,159	$ 13,838,602	$ 13,244,230
Real-estate - home equity [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	1,647,319	1,684,439	1,689,688
Real-estate - residential mortgage [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	1,447,292	1,376,160	1,369,103
Construction other [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	65,919	60,694
Consumer [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	278,071	268,588	272,494
Consumer - direct [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	96,461	98,719
Consumer - Indirect [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	181,610	169,869
Leasing and other and overdrafts [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	194,254	158,135	$ 136,521
Real Estate, Home Equity, Construction, Other, Consumer and Leasing [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	3,632,855	3,548,016
Commercial Loans, Commerical Mortgages, Constructions Loans [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	$ 10,522,304	$ 10,290,586
% of Total	100.00%	100.00%
Performing Financing Receivable [Member] | Real-estate - home equity [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	$ 1,623,095	$ 1,660,773
Performing Financing Receivable [Member] | Real-estate - residential mortgage [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	1,408,244	1,329,371
Performing Financing Receivable [Member] | Construction other [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	63,404	59,997
Performing Financing Receivable [Member] | Consumer [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	272,199	261,085
Performing Financing Receivable [Member] | Consumer - direct [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	92,906	94,262
Performing Financing Receivable [Member] | Consumer - Indirect [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	179,293	166,823
Performing Financing Receivable [Member] | Leasing and other and overdrafts [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	193,233	155,870
Performing Financing Receivable [Member] | Real Estate, Home Equity, Construction, Other, Consumer and Leasing [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	$ 3,560,175	$ 3,467,096
Performing Financing Receivable [Member] | Commercial Loans, Commerical Mortgages, Constructions Loans [Member]
Financing Receivable, Impaired [Line Items]
% of Total	98.00%	97.70%
Delinquent [Member] | Real-estate - home equity [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	$ 10,051	$ 8,983
Delinquent [Member] | Real-estate - residential mortgage [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	14,018	18,305
Delinquent [Member] | Construction other [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	1,416	88
Delinquent [Member] | Consumer [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	3,984	5,063
Delinquent [Member] | Consumer - direct [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	1,860	2,254
Delinquent [Member] | Consumer - Indirect [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	2,124	2,809
Delinquent [Member] | Leasing and other and overdrafts [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	863	759
Delinquent [Member] | Real Estate, Home Equity, Construction, Other, Consumer and Leasing [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	$ 30,332	$ 33,198
Delinquent [Member] | Commercial Loans, Commerical Mortgages, Constructions Loans [Member]
Financing Receivable, Impaired [Line Items]
% of Total	0.80%	1.00%
Nonperforming Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Days past due | day	90
Nonperforming Financing Receivable [Member] | Real-estate - home equity [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	$ 14,173	$ 14,683
Nonperforming Financing Receivable [Member] | Real-estate - residential mortgage [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	25,030	28,484
Nonperforming Financing Receivable [Member] | Construction other [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	1,099	609
Nonperforming Financing Receivable [Member] | Consumer [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	1,888	2,440
Nonperforming Financing Receivable [Member] | Consumer - direct [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	1,695	2,203
Nonperforming Financing Receivable [Member] | Consumer - Indirect [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	193	237
Nonperforming Financing Receivable [Member] | Leasing and other and overdrafts [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	158	1,506
Nonperforming Financing Receivable [Member] | Real Estate, Home Equity, Construction, Other, Consumer and Leasing [Member]
Financing Receivable, Impaired [Line Items]
Loans, net of unearned income	$ 42,348	$ 47,722
Nonperforming Financing Receivable [Member] | Commercial Loans, Commerical Mortgages, Constructions Loans [Member]
Financing Receivable, Impaired [Line Items]
% of Total	1.20%	1.30%
Minimum [Member] | Delinquent [Member]
Financing Receivable, Impaired [Line Items]
Days past due | day	30
Maximum [Member] | Delinquent [Member]
Financing Receivable, Impaired [Line Items]
Days past due | day	89