Consolidated Securitization Vehicles (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2013		Dec. 31, 2011		Dec. 31, 2012
Net book value	$ 139,500				$ 141,500
Securitization Vehicles | Loans Receivable
Number of investments	6				7
Principal balance	157,579				164,180
Net book value	$ 139,500				$ 141,500
Coupon	4.64%	[1],[2]			4.73%	[1],[2]
Yield	3.57%	[1],[2]			4.74%	[1],[2]
Maturity (years)	6 months	[1]	8 months	[1]

[1] Represents a weighted average as of March 31, 2013 and December 31, 2012, respectively.

[2] All loans are floating rate loans as of both March 31, 2013 and December 31, 2012. Calculations are based on LIBOR of 0.20% and 0.30% as of March 31, 2013 and December 31, 2012, respectively.