Consolidated Securitization Vehicles (Details 5) (Securitization Vehicles, USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Less than 12 months, Estimated Fair Value	$ 25,500		$ 154,100
Less than 12 months, Gross Unrealized Losses	(10,600)		(4,700)
Greater than 12 months , Estimated Fair Value	86,300		130,100
Greater than 12 months , Gross Unrealized Losses	(10,100)		(11,100)
Total, Estimated Fair Value	111,800		284,200
Total Gross Unrealized Losses	(20,700)		(15,800)
[HeldToMaturitySecuritiesExcluded]	132,500	[1]	300,000	[2]
Floating Rate
Less than 12 months, Estimated Fair Value
Less than 12 months, Gross Unrealized Losses
Greater than 12 months , Estimated Fair Value
Greater than 12 months , Gross Unrealized Losses
Total, Estimated Fair Value
Total Gross Unrealized Losses
[HeldToMaturitySecuritiesExcluded]		[1]		[2]
Fixed Rate
Less than 12 months, Estimated Fair Value	25,500		154,100
Less than 12 months, Gross Unrealized Losses	(10,600)		(4,700)
Greater than 12 months , Estimated Fair Value	86,300		130,100
Greater than 12 months , Gross Unrealized Losses	(10,100)		(11,100)
Total, Estimated Fair Value	111,800		284,200
Total Gross Unrealized Losses	(20,700)		(15,800)
[HeldToMaturitySecuritiesExcluded]	$ 132,500	[1]	$ 300,000	[2]

[1] Excludes, as of June 30, 2012, $34.1 million of securities which were carried at or below fair value and securities against which an other-than-temporary impairment equal to the entire book value was recognized in earnings.

[2] Excludes, as of December 31, 2011, $59.0 million of securities which were carried at or below fair value and securities against which an other-than-temporary impairment equal to the entire book value was recognized in earnings.