Real Estate Debt Investments (Details 2) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013 investment	Dec. 31, 2012
Maturities of principal amounts of CRE debt investments
Total	$ 945,910	$ 543,619
Credit Quality Monitoring
Number of CRE debt investments contributing to more than 10% of interest income	0
Minimum
Credit Quality Monitoring
Period past due on contractual debt service payments for debt investments to be categorized as non-performing loans	90 days
Initial Maturity
Maturities of principal amounts of CRE debt investments
July 1 - December 31, 2013	64,480
2014	114,310
2015	418,070
2016	259,800
Thereafter	89,250
Total	945,910
Maturity Including Extensions
Maturities of principal amounts of CRE debt investments
2014	52,000
2015	12,480
2016	179,512
2017	352,868
Thereafter	349,050
Total	$ 945,910