Loans And Allowance For Loan Losses (Summary Classification Of Held To Maturity Loan Portfolio) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Loans And Allowance For Loan Losses [Line Items]
Total loans	$ 13,954,111	$ 13,983,674
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	4,990,298	4,958,554
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	967,151	968,820
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	2,727,580	2,697,452
Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	2,102,586	2,062,787
Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	2,012,644	2,104,487
Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	374,557	400,587
Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	775,214	783,864
Overdrafts [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	$ 4,081	$ 7,123