Loans (Schedule Of Loans By Portfolio Segment) (Details) - USD ($) $ in Thousands	Sep. 30, 2017		Jun. 30, 2017	Dec. 31, 2016		Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 20,166,091	[1]		$ 19,589,520	[1]	$ 19,555,787
Allowance for loan losses	194,867		$ 197,257	202,068		201,557	$ 199,807	$ 210,242
Total net loans	19,971,224			19,387,452
Commercial Financial And Industrial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	12,791,844			12,148,087		12,118,298
Allowance for loan losses	98,205		92,379	89,398		86,866	80,972	73,637
Commercial Real Estate Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	2,251,015			2,135,523		2,065,595
Allowance for loan losses	29,683		30,470	33,852		32,420	30,264	25,159
Consumer Real Estate Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	4,369,717			4,523,752		4,578,371
Allowance for loan losses	40,939		46,069	50,357		53,235	59,081	80,614
Permanent Mortgage Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	403,082			423,125		436,100
Allowance for loan losses	15,719		16,398	16,289		16,589	17,600	18,947
Credit Card And Other Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	350,433			359,033		357,423
Allowance for loan losses	10,321		$ 11,941	12,172		$ 12,447	$ 11,890	$ 11,885
Restricted And Secured Consumer Real Estate Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 26,200			$ 35,900

[1] September 30, 2017 and December 31, 2016 include $24.8 million and $28.5 million, respectively, of held-to-maturity consumer mortgage loans secured by residential real estate properties in process of foreclosure.