Loans and Allowance for Credit Losses Summary Of Gross Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	$ 15,954,326	$ 15,795,918
Unearned income	(29,233)	(27,671)
Loans, net of unearned income	15,925,093	15,768,247	$ 15,486,899
Real-estate - commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	6,337,984	6,364,804
Loans, net of unearned income	6,337,984	6,364,804	6,275,140
Commercial - industrial, financial and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	4,288,823	4,300,297
Loans, net of unearned income	4,288,823	4,300,297	4,223,075
Real-estate - home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	1,469,152	1,559,719
Loans, net of unearned income	1,469,152	1,559,719	1,567,473
Real estate - residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	2,173,548	1,954,711
Loans, net of unearned income	2,173,548	1,954,711	1,887,907
Real-estate - construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	979,857	1,006,935
Loans, net of unearned income	979,857	1,006,935	973,108
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	390,708	313,783
Loans, net of unearned income	390,708	313,783	$ 302,448
Leasing and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	312,207	291,556
Overdrafts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, gross of unearned income	$ 2,047	$ 4,113

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Amount of deferred interest and fee income, unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of acquired loans. Excludes amounts for loans and leases covered under loss sharing agreements.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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