Loans and Allowance for Credit Losses Summary of Delinquency and Non-Performing Status by Portfolio Segment (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2019 USD ($) day	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	$ 16,368,458	$ 16,165,800	$ 15,792,969
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	$ 1,386,974	1,452,137	1,491,395
Real-estate - home equity | Performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	1,363,344	1,431,666
Real-estate - home equity | Delinquent
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	11,634	10,702
Real-estate - home equity | Non-performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	11,996	9,769
Real estate - residential mortgage
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	2,451,966	2,251,044	2,094,530
Real estate - residential mortgage | Performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	2,398,432	2,202,955
Real estate - residential mortgage | Delinquent
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	31,876	28,988
Real estate - residential mortgage | Non-performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	21,658	19,101
Construction - other
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	76,854	72,001
Construction - other | Performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	76,116	71,511
Construction - other | Delinquent
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	549	0
Construction - other | Non-performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	189	490
Consumer
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	58,713	56,033
Consumer | Performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	58,295	55,629
Consumer | Delinquent
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	295	338
Consumer | Non-performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	123	66
Consumer - indirect
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	394,161	363,153
Consumer - indirect | Performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	390,394	359,405
Consumer - indirect | Delinquent
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	3,508	3,405
Consumer - indirect | Non-performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	259	343
Consumer
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	452,874	419,186	360,315
Consumer | Performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	448,689	415,034
Consumer | Delinquent
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	3,803	3,743
Consumer | Non-performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	382	409
Equipment lease financing, other and overdrafts
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	290,876	288,001	$ 286,947
Equipment lease financing, other and overdrafts | Performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	271,130	267,112
Equipment lease financing, other and overdrafts | Delinquent
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	1,808	1,302
Equipment lease financing, other and overdrafts | Non-performing
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	17,938	19,587
Real Estate, Consumer, Leasing And Other Loans [Member] [Member]
Financing Receivable, Impaired [Line Items]
Loans and leases, net of unearned income	4,659,544	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	4,557,711	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	49,670	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	$ 52,163	$ 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	97.80%	97.90%
Commercial Loans, Commerical Mortgages, Constructions Loans | Delinquent
Financing Receivable, Impaired [Line Items]
% of Total	1.10%	1.00%
Commercial Loans, Commerical Mortgages, Constructions Loans | Non-performing
Financing Receivable, Impaired [Line Items]
% of Total	1.10%	1.10%