Repurchase Arrangements And Similar Borrowings, Including Related Hedging Activity (Schedule Of Repurchase Arrangements And Similar Borrowings, Classified By Type Of Collateral And Remaining Maturities And Related Weighted Average Interest Rates) (Details) (USD $) In Thousands, unless otherwise specified										9 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010	Sep. 30, 2011 Borrowings With Maturities Of 30 Days Or Less [Member]	Dec. 31, 2010 Borrowings With Maturities Of 30 Days Or Less [Member]	Sep. 30, 2011 Borrowings With Maturities Of 31 To 90 Days [Member]	Dec. 31, 2010 Borrowings With Maturities Of 31 To 90 Days [Member]	Sep. 30, 2011 Borrowings With Maturities Of 91 To 365 Days [Member]	Dec. 31, 2010 Borrowings With Maturities Of 91 To 365 Days [Member]	Sep. 30, 2011 Structured Financings Secured By Private Residential Mortgage Securities [Member]	Dec. 31, 2010 Structured Financings Secured By Private Residential Mortgage Securities [Member]	Sep. 30, 2011 Agency Securities [Member]	Dec. 31, 2010 Agency Securities [Member]	Sep. 30, 2011 Quarter-End Rates Adjusted For Effects Of Related Derivatives Held As Cash Flow Hedges [Member]	Dec. 31, 2010 Quarter-End Rates Adjusted For Effects Of Related Derivatives Held As Cash Flow Hedges [Member]
Repurchase Arrangements And Similar Borrowings, Including Related Hedging Activity [Line Items]
Secured Debt Outstanding	$ 11,087,863	$ 7,792,743		$ 9,940,856	$ 7,554,225	$ 1,096,227	$ 235,000	$ 47,419	$ 0			$ 11,087,863	$ 7,792,743
Secured Debt Outstanding										$ 3,361	$ 3,518
Unsecured Borrowings, Average rate	8.49%	8.49%	8.49%	0.27%	0.30%	0.27%	0.33%	0.35%	0.00%	8.04%	7.97%	0.28%	0.31%	0.54%	0.63%