Debt and Preferred Equity Investments (Details 2) (USD $)				6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Dec. 31, 2010	Jun. 30, 2012 Preferred equity investments	Dec. 31, 2011 Preferred equity investments	Jun. 30, 2012 Preferred equity with initial mandatory redemption on July, 2016	Dec. 31, 2011 Preferred equity with initial mandatory redemption on July, 2016	Jun. 30, 2012 Preferred equity with initial mandatory redemption on April, 2016	Jun. 30, 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)				11.14%
Senior Financing	$ 3,815,340,000			$ 2,437,868,000		$ 926,260,000		$ 56,935,000	$ 480,000,000		$ 974,673,000
Carrying Value, Net of Discounts, at fixed rate						206,931,000	203,080,000	16,042,000	95,653,000	141,980,000	50,716,000	51,000,000
Loan loss reserve	(41,050,000)	(50,175,000)	(61,361,000)	(34,050,000)	(31,050,000)
Carrying Value, Net of Discounts, at floating rate	982,209,000	985,942,000
Additional commitments to fund in connection with loan								10,000,000
Junior preferred equity loan									$ 50,000,000
Interest in property (as a percent)											100.00%