Loans (Schedule Of Loans By Portfolio Segment) (Details) - USD ($) $ in Thousands	Mar. 31, 2018		Dec. 31, 2017		Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 27,249,793	[1]	$ 27,658,929	[1]	$ 19,090,074
Allowance for loan losses	187,194		189,555		201,968	$ 202,068
Total net loans	27,062,599		27,469,374
Commercial Financial And Industrial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	15,828,308		16,057,273		11,703,996
Allowance for loan losses	100,238		98,211		93,107	89,398
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	4,234,435		4,214,695		2,173,311
Allowance for loan losses	29,057		28,427		30,888	33,852
Consumer Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	6,246,552		6,367,755		4,456,811
Allowance for loan losses	32,750		37,371		49,680	50,357
Permanent Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	379,688		399,307		409,235
Allowance for loan losses	15,435		15,565		15,893	16,289
Credit Card and Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	560,810		619,899		346,721
Allowance for loan losses	9,714		9,981		$ 12,400	$ 12,172
Restricted And Secured Consumer Real Estate Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 21,300		$ 24,200

[1] March 31, 2018 and December 31, 2017 include $21.5 million and $22.7 million, respectively, of held-to-maturity consumer mortgage loans secured by residential real estate in process of foreclosure.