Loans And Allowance For Loan Losses (Summary Classification Of Held To Maturity Loan Portfolio) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans And Allowance For Loan Losses [Line Items]
Total loans	$ 13,893,361	$ 13,983,674
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	4,960,614	4,958,554
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	932,058	968,820
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	2,724,584	2,697,452
Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	2,069,012	2,062,787
Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	2,069,235	2,104,487
Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	382,825	400,587
Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	752,651	783,864
Overdrafts [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	$ 2,382	$ 7,123