Loans and Allowance for Credit Losses Summary of Delinquency and Non-Performing Status by Portfolio Segment (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($) day	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	$ 16,686,866	$ 16,165,800	$ 15,925,093
Delinquent | Minimum
Financing Receivable, Impaired [Line Items]
Days past due | day	30
Delinquent | Maximum
Financing Receivable, Impaired [Line Items]
Days past due | day	89
Non-performing
Financing Receivable, Impaired [Line Items]
Days past due | day	90
Real-estate - home equity
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	$ 1,346,115	1,452,137	1,469,152
Real-estate - home equity | Performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	1,325,900	1,431,666
Real-estate - home equity | Delinquent
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	9,445	10,702
Real-estate - home equity | Non-performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	10,770	9,769
Real estate - residential mortgage
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	2,570,793	2,251,044	2,173,548
Real estate - residential mortgage | Performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	2,526,551	2,202,955
Real estate - residential mortgage | Delinquent
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	24,092	28,988
Real estate - residential mortgage | Non-performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	20,150	19,101
Construction - other
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	84,270	72,001
Construction - other | Performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	82,787	71,511
Construction - other | Delinquent
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	1,296	0
Construction - other | Non-performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	187	490
Consumer
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	64,801	56,033
Consumer | Performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	64,066	55,629
Consumer | Delinquent
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	641	338
Consumer | Non-performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	94	66
Consumer - indirect
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	399,412	363,153
Consumer - indirect | Performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	395,919	359,405
Consumer - indirect | Delinquent
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	3,345	3,405
Consumer - indirect | Non-performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	148	343
Consumer
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	464,213	419,186	390,708
Consumer | Performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	459,985	415,034
Consumer | Delinquent
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	3,986	3,743
Consumer | Non-performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	242	409
Equipment lease financing, other and overdrafts
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	292,971	288,001	$ 285,021
Equipment lease financing, other and overdrafts | Performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	274,239	267,112
Equipment lease financing, other and overdrafts | Delinquent
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	1,066	1,302
Equipment lease financing, other and overdrafts | Non-performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	17,666	19,587
Real Estate, Consumer, Leasing And Other Loans [Member] [Member]
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	4,758,362	4,482,369
Real Estate, Consumer, Leasing And Other Loans [Member] [Member] | Performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	4,669,462	4,388,278
Real Estate, Consumer, Leasing And Other Loans [Member] [Member] | Delinquent
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	39,885	44,735
Real Estate, Consumer, Leasing And Other Loans [Member] [Member] | Non-performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	$ 49,015	$ 49,356
Commercial Loans, Commerical Mortgages, Constructions Loans
Financing Receivable, Impaired [Line Items]
% of Total	100.00%	100.00%
Commercial Loans, Commerical Mortgages, Constructions Loans | Performing
Financing Receivable, Impaired [Line Items]
% of Total	98.10%	97.90%
Commercial Loans, Commerical Mortgages, Constructions Loans | Delinquent
Financing Receivable, Impaired [Line Items]
% of Total	0.90%	1.00%
Commercial Loans, Commerical Mortgages, Constructions Loans | Non-performing
Financing Receivable, Impaired [Line Items]
% of Total	1.00%	1.10%