Loans - Schedule Of Loans By Portfolio Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2019		Jun. 30, 2019	Dec. 31, 2018		Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 31,260,833	[1]		$ 27,535,532	[1]	$ 27,350,214
Allowance for loan losses	193,149		$ 192,749	180,424		185,959	$ 185,462	$ 189,555
Total net loans	31,067,684			27,355,108
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	149,755			130,258
Commercial | Commercial, financial, and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	20,293,930			16,514,328		16,044,145
Allowance for loan losses	114,130		116,096	98,947		100,314	96,834	98,211
Commercial | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	4,228,598			4,030,870		4,237,036
Allowance for loan losses	35,625		32,953	31,311		33,915	33,832	28,427
Consumer | Consumer real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	6,062,829			6,249,516		6,300,983
Allowance for loan losses	21,837		22,857	26,439		28,919	34,155	39,823
Consumer | Permanent mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	182,467			222,448		237,254
Allowance for loan losses	8,837		8,675	11,000		11,098	11,692	13,113
Consumer | Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	493,009			518,370		530,796
Allowance for loan losses	12,720		$ 12,168	12,727		11,713	$ 8,949	$ 9,981
Consumer | Restricted and secured consumer real estate loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 12,400			$ 16,200
Restatement Adjustment | Commercial | Commercial, financial, and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income						(410,000)
Restatement Adjustment | Commercial | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income						$ 410,000

[1] September 30, 2019 and December 31, 2018 include $18.2 million and $28.6 million, respectively, of held-to-maturity consumer mortgage loans secured by residential real estate in process of foreclosure.