Loans And Allowance For Loan Losses (Summary Classification Of Held To Maturity Loan Portfolio) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Loans And Allowance For Loan Losses [Line Items]
Total loans	$ 13,955,559	$ 13,983,674
Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	4,966,722	4,958,554
Real Estate - Construction And Land [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	999,691	968,820
Real Estate - Business [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	2,726,042	2,697,452
Real Estate - Personal [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	2,120,672	2,062,787
Consumer [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	1,967,465	2,104,487
Revolving Home Equity [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	375,322	400,587
Consumer Credit Card [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	788,111	783,864
Overdrafts [Member]
Loans And Allowance For Loan Losses [Line Items]
Total loans	$ 11,534	$ 7,123