Repurchase Arrangements And Similar Borrowings, Including Related Hedging Activity (Schedule Of Swap Agreements Expiration Period And Characteristics) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2010	Mar. 31, 2012 Currently-Paying Contracts [Member]	Mar. 31, 2012 Forward-Starting Contracts [Member]	Mar. 31, 2012 Third Quarter 2012 [Member] Currently-Paying Contracts [Member]	Mar. 31, 2012 First Quarter 2013 [Member] Currently-Paying Contracts [Member]	Mar. 31, 2012 Second Quarter 2013 [Member] Currently-Paying Contracts [Member]	Mar. 31, 2012 Third Quarter 2013 [Member] Currently-Paying Contracts [Member]	Mar. 31, 2012 Fourth Quarter 2013 [Member] Currently-Paying Contracts [Member]	Mar. 31, 2012 First Quarter 2014 [Member] Currently-Paying Contracts [Member]	Mar. 31, 2012 Second Quarter 2014 [Member] Forward-Starting Contracts [Member]	Mar. 31, 2012 Third Quarter 2014 [Member] Forward-Starting Contracts [Member]	Mar. 31, 2012 Fourth Quarter 2014 [Member] Forward-Starting Contracts [Member]
Repurchase Arrangements And Similar Borrowings, Including Interest Rate Hedging Activity [Line Items]
Notional Amount	$ 100,000	$ 3,300,000	$ 4,400,000	$ 200,000	$ 1,100,000	$ 700,000	$ 300,000	$ 800,000	$ 200,000	$ 400,000	$ 200,000	$ 500,000
Average Fixed Rate Payment Requirement	4.09%	0.83%		0.83%	0.81%	0.96%	0.87%	0.78%	0.60%	0.51%	0.51%	0.58%