Consolidated Securitization Vehicles (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Book Value, net	$ 141,500	$ 838,394
Consolidated Securization Vehicles | Loans Receivable
Number of Loans	7	12
Principal Balance	164,180	228,151
Book Value, net	141,500	145,491
Consolidated Securization Vehicles | Loans Receivable | Risk Rating 1-3
Number of Loans	2	5
Principal Balance	47,000	142,202
Book Value, net	47,000	142,202
Consolidated Securization Vehicles | Loans Receivable | Risk Rating 4-5
Number of Loans	2
Principal Balance	92,500
Book Value, net	92,500
Consolidated Securization Vehicles | Loans Receivable | Risk Rating 6-8
Number of Loans	3	7
Principal Balance	24,680	85,949
Book Value, net	2,000	3,289
Consolidated Securization Vehicles | Senior Mortgage Loans
Number of Loans	1	1
Principal Balance	62,500	65,000
Book Value, net	62,500	65,000
Consolidated Securization Vehicles | Senior Mortgage Loans | Risk Rating 1-3
Number of Loans		1
Principal Balance		65,000
Book Value, net		65,000
Consolidated Securization Vehicles | Senior Mortgage Loans | Risk Rating 4-5
Number of Loans	1
Principal Balance	62,500
Book Value, net	62,500
Consolidated Securization Vehicles | Subordinated interests in mortgages
Number of Loans	6	11
Principal Balance	101,680	163,151
Book Value, net	79,000	80,491
Consolidated Securization Vehicles | Subordinated interests in mortgages | Risk Rating 1-3
Number of Loans	2	4
Principal Balance	47,000	77,202
Book Value, net	47,000	77,202
Consolidated Securization Vehicles | Subordinated interests in mortgages | Risk Rating 4-5
Number of Loans	1
Principal Balance	30,000
Book Value, net	30,000
Consolidated Securization Vehicles | Subordinated interests in mortgages | Risk Rating 6-8
Number of Loans	3	7
Principal Balance	24,680	85,949
Book Value, net	$ 2,000	$ 3,289