Loans And Allowance For Loan Losses (Allowance For Loan Losses And Related Loan Balance Disaggregated On The Basis Of Impairment Methodology) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans And Allowance For Loan Losses [Line Items]
Loans And Leases Receivable Excluding Impaired Financing Receivables Recorded Investment	$ 13,789,834	$ 13,868,879
Impaired Financing Receivable, Recorded Investment	103,527	114,795
Loans and Leases Receivable Allowance Excluding Impaired Financing Receivable Related Allowance	156,034	155,289
Impaired Financing Receivable, Related Allowance	3,498	4,243
Commercial Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans And Leases Receivable Excluding Impaired Financing Receivables Recorded Investment	8,534,557	8,532,213
Impaired Financing Receivable, Recorded Investment	82,699	92,613
Loans and Leases Receivable Allowance Excluding Impaired Financing Receivable Related Allowance	90,674	90,637
Impaired Financing Receivable, Related Allowance	2,391	3,067
Personal Banking Portfolio Segment [Member]
Loans And Allowance For Loan Losses [Line Items]
Loans And Leases Receivable Excluding Impaired Financing Receivables Recorded Investment	5,255,277	5,336,666
Impaired Financing Receivable, Recorded Investment	20,828	22,182
Loans and Leases Receivable Allowance Excluding Impaired Financing Receivable Related Allowance	65,360	64,652
Impaired Financing Receivable, Related Allowance	$ 1,107	$ 1,176