Debt and Preferred Equity Investments (Details 2) (USD $)	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Preferred equity investment
Aggregate weighted average current yield (as a percent)	11.20%
Senior Financing	$ 4,277,860,000
Carrying Value, Net of Discounts and Deferred Origination Fees, at floating rate	1,227,421,000	1,348,434,000
Preferred equity investments
Preferred equity investment
Aggregate weighted average current yield (as a percent)	10.20%
Senior Financing	1,577,246,000
Carrying Value, Net of Discounts and Deferred Origination Fees, at fixed rate	351,301,000	338,579,000
Preferred equity with initial mandatory redemption on July, 2015
Preferred equity investment
Senior Financing	525,000,000
Carrying Value, Net of Discounts and Deferred Origination Fees, at floating rate	105,360,000	99,768,000
Preferred equity with initial mandatory redemption on October, 2014
Preferred equity investment
Senior Financing	70,000,000
Carrying Value, Net of Discounts and Deferred Origination Fees, at floating rate	9,934,000	9,927,000
Preferred equity with initial mandatory redemption on April, 2016
Preferred equity investment
Senior Financing	55,986,000
Carrying Value, Net of Discounts and Deferred Origination Fees, at floating rate	22,213,000	18,925,000
Additional commitments to fund in connection with loan	3,600,000
Preferred equity with initial mandatory redemption on July, 2016
Preferred equity investment
Senior Financing	926,260,000
Carrying Value, Net of Discounts and Deferred Origination Fees, at floating rate	$ 213,794,000	$ 209,959,000