Debt and Preferred Equity Investments (Details 2) (USD $)					12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2011 Preferred equity investments	Dec. 31, 2010 Preferred equity investments	Dec. 31, 2011 Preferred equity with initial mandatory redemption on July, 2014	Dec. 31, 2010 Preferred equity with initial mandatory redemption on July, 2014	Dec. 31, 2011 Preferred equity with initial mandatory redemption on August, 2012	Dec. 31, 2010 Preferred equity with initial mandatory redemption on August, 2012	Dec. 31, 2011 Preferred equity with initial mandatory redemption on July, 2016
Preferred equity investment
Aggregate weighted average current yield (as a percent)					9.80%	9.80%
Senior Financing					$ 2,382,150,000		$ 480,000,000		$ 975,890,000		$ 926,260,000
Amount Outstanding, Net of Discounts							141,980,000	45,912,000	51,000,000	46,372,000	203,080,000
Loan loss reserve	(50,175,000)	(61,361,000)	(93,844,000)	(98,916,000)	(31,050,000)	(20,900,000)
Amount Outstanding, Net of Discounts	985,942,000	963,772,000			365,010,000	71,384,000
Preferred equity loans granted							$ 50,000,000