Commitments, Credit Risk And Contingencies (Summary Of Off-Balance Sheet Credit Risk Information) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2011	Dec. 31, 2010
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Percentage of commitments to extend credit dependent upon the financial condition of the customers	80.70%
Commitments To Extend Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Extended credit and standby letters of credit	$ 1,837,315	$ 1,550,256
Standby Letters Of Credit [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]
Extended credit and standby letters of credit	$ 112,431	$ 101,185