Debt and Preferred Equity Investments (Details 2) (USD $)					12 Months Ended									1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2012 Preferred equity investments	Dec. 31, 2011 Preferred equity investments	Dec. 31, 2012 Preferred equity with initial mandatory redemption on July, 2016	Dec. 31, 2011 Preferred equity with initial mandatory redemption on July, 2016	Dec. 31, 2012 Preferred equity with initial mandatory redemption on April, 2016	Dec. 31, 2012 Preferred equity with initial mandatory redemption of October 2014	Dec. 31, 2012 Preferred equity with initial mandatory redemption on July, 2014	Feb. 29, 2012 Preferred equity with initial mandatory redemption on July, 2014	Dec. 31, 2011 Preferred equity with initial mandatory redemption on July, 2014	Jun. 30, 2012 Preferred equity with initial mandatory redemption on August, 2012	Dec. 31, 2011 Preferred equity with initial mandatory redemption on August, 2012
Preferred equity investment
Aggregate weighted average current yield (as a percent)					10.12%
Senior Financing	$ 2,899,673,000				$ 1,533,347,000		$ 926,260,000		$ 57,087,000	$ 70,000,000	$ 480,000,000
Carrying Value, Net of Discounts					340,885,000		210,918,000	203,080,000	19,136,000	10,000,000	100,831,000		141,980,000		51,000,000
Loan loss reserve	(7,000,000)	(50,175,000)	(61,361,000)	(93,844,000)		(31,050,000)
Carrying Value after deduction of loan loss reserves	1,357,203,000	985,942,000				365,010,000
Junior preferred equity loan												50,000,000
Committed additional capital contribution funded									$ 6,500,000
Acquisition of interest (as a percent)														100.00%