Debt and Preferred Equity Investments (Details 2) (USD $)	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Preferred equity investment
Aggregate weighted average current yield (as a percent)	11.10%
Senior Financing	$ 4,073,528,000
Carrying Value, Net of Discounts, at floating rate	1,443,834,000	1,357,203,000
Preferred equity investments
Preferred equity investment
Aggregate weighted average current yield (as a percent)	11.40%
Senior Financing	1,533,347,000
Carrying Value, Net of Discounts, at fixed rate	346,607,000	340,885,000
Preferred equity with initial mandatory redemption on July, 2014
Preferred equity investment
Senior Financing	480,000,000
Carrying Value, Net of Discounts, at floating rate	103,437,000	100,831,000
Junior preferred equity loan	50,000,000
Preferred equity with initial mandatory redemption on October, 2014
Preferred equity investment
Senior Financing	70,000,000
Carrying Value, Net of Discounts, at floating rate	10,000,000	10,000,000
Preferred equity with initial mandatory redemption on April, 2016
Preferred equity investment
Senior Financing	57,087,000
Carrying Value, Net of Discounts, at floating rate	20,238,000	19,136,000
Additional commitments to fund in connection with loan	5,700,000
Preferred equity with initial mandatory redemption on July, 2016
Preferred equity investment
Senior Financing	926,260,000
Carrying Value, Net of Discounts, at floating rate	$ 212,932,000	$ 210,918,000