Guarantees, Commitments And Contingencies (Schedule Of Guarantees Issued) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Standby letters of credit	$ 1,049,952	$ 1,080,284
Financial [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Standby letters of credit	883,714	914,986
Performance [Member]
Liabilities for Guarantees on Long-Duration Contracts [Line Items]
Standby letters of credit	$ 166,238	$ 165,298