Consolidated Securitization Vehicles (Details 1) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net	$ 141,500	$ 838,394
Consolidated Securization 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	89,500
Percentage of Book Value	65.00%	62.00%
Consolidated Securization 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%
Consolidated Securization 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	15,142
Percentage of Book Value	9.00%	10.00%
Consolidated Securization Vehicles | Southwest
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net	9,596	13,350
Percentage of Book Value	7.00%	9.00%
Consolidated Securization Vehicles | Midwest
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net		499
Percentage of Book Value
Consolidated Securization Vehicles | Office
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net	111,500	139,789
Percentage of Book Value	79.00%	96.00%
Consolidated Securization 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	5,702
Percentage of Book Value	21.00%	4.00%
Consolidated Securization 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	79,000	80,491
Percentage of Book Value	56.00%	55.00%
Consolidated Securization Vehicles | Senior Mortgage Loans
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net	62,500	65,000
Percentage of Book Value	44.00%	45.00%
Consolidated Securization Vehicles | Loans Receivable
Types of loans as well as the property type and geographic distribution of the properties securing these loans
Book Value, net	$ 141,500	$ 145,491
Percentage of Book Value	100.00%	100.00%