Consolidated Securitization Vehicles (Details 1) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net	$ 139,500	$ 141,500
Securitization Vehicles | West
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net	92,500	92,500
Percentage of Book Value	62.00%	65.00%
Securitization Vehicles | Northeast
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net	27,000	27,000
Percentage of Book Value	19.00%	19.00%
Securitization Vehicles | Southeast
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net	12,404	12,404
Percentage of Book Value	10.00%	9.00%
Securitization Vehicles | Southwest
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net	7,596	9,596
Percentage of Book Value	5.00%	7.00%
Securitization Vehicles | Office
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net	109,500	111,500
Percentage of Book Value	78.00%	79.00%
Securitization Vehicles | Hotel
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net	30,000	30,000
Percentage of Book Value	22.00%	21.00%
Securitization Vehicles | Subordinated interests in mortgages
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net	77,000	79,000
Percentage of Book Value	55.00%	56.00%
Securitization Vehicles | Senior Mortgages
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net	62,500	62,500
Percentage of Book Value	45.00%	44.00%
Securitization Vehicles | Loans Receivable
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net	$ 139,500	$ 141,500
Percentage of Book Value	100.00%	100.00%