Subsequent Events (Details)	9 Months Ended				0 Months Ended		1 Months Ended	0 Months Ended				0 Months Ended
	Sep. 30, 2013 USD ($)	Dec. 31, 2012 USD ($)	Sep. 30, 2013 Mezzanine loan secured by indirect equity interests in subsidiaries USD ($)	Dec. 14, 2012 SEREF USD ($)	Sep. 30, 2013 Subsequent event Mezzanine loan secured by the Hyatt Regency, located in New Orleans USD ($)	Sep. 30, 2013 Subsequent event First mortgage secured by multifamily units and ground floor retails units, located in San Francisco, CA USD ($) item	Oct. 31, 2013 Subsequent event Mezzanine loan secured by indirect equity interests in subsidiaries USD ($)	Sep. 30, 2013 Subsequent event SEREF First mortgage collateralized by the Heron Tower, located in London USD ($)	Sep. 30, 2013 Subsequent event SEREF First mortgage collateralized by the Heron Tower, located in London GBP (£)	Sep. 30, 2013 Subsequent event Preferred equity investment USD ($) item sqft	Sep. 30, 2013 Subsequent event SWAY Expected Minimum USD ($)	Oct. 31, 2013 Subsequent event Spin off Expected USD ($)
Subsequent Events
Cash contribution												$ 100,000,000
Initial borrowing capacity											400,000,000
Share exchange ratio												0.20
Acquisitions/Origination	2,506,378,000				106,000,000	86,000,000			288,000,000
LIBOR-based collateralized term financing facility									210,000,000
Amount funded at closing					84,000,000
Amount retained as Junior investment								60,000,000
Number of multifamily units collateralized against loan						432
Number of ground floor retails collateralized against loan						23
Amount of loan owned	4,220,991,000	3,000,335,000	217,600,000
Proceeds from sale of loan, net of repayment of financing facility secured							63,600,000
Repayment of financing facility secured by investment							140,200,000
Value of investment at origination				$ 14,700,000						$ 250,000,000
Number of properties in portfolio investment										41
Area of property										9,100,000