Consolidated Securitization Vehicles (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012 Securities	Dec. 31, 2011
Total assets	$ 62,767	$ 70,300
Total liabilties	26,160	35,204
Securitization Vehicles
Total assets	402,185	1,040,921
Total liabilties	517,071	1,239,451
Number of consolidated securization vehicles	4
Impairment previously recorded in other comprehensive income	160
Number of investments	33	52
Estimated Fair Value	144,700	350,200
Securities held-to-maturity	154,848	358,972	[1]
Number of loans	2
Book value of loans in maturity default	52,700
Non-recourse securitized debt obligations	497,423	1,211,407
Maximum potential amount of future payment	722,500
Expected reclassified from other comprehensive income to interest expense	9,800
Number of securities recognized other-than-temporary-impairment	11
Securitization Vehicles | Subordinated interests in mortgages
Troubled debt restructuring - loan principal balance	6,600
Trouble debt restructing - impairment	4,600
Securitization Vehicles | CT CDOs
Number of consolidated securization vehicles	3
Notional Amounts of subordinated debt and equity interests	162,000
Non-recourse securitized debt obligations	446,871	742,253
Number of issuances	3	4
Face amount of issuances	467,600
Loans receivable, CT CDOs	149,500	208,300
Securities financed by CT CDOs	154,800	359,000
Securitization Vehicles | Other Consolidation Securization Vehicles
Loans receivable, CT CDOs	65,000	404,300
Securitization Vehicles | CMBS
Impairment previously recorded in other comprehensive income	160
Number of investments	29	51
Estimated Fair Value	126,100	348,300
Securities held-to-maturity	124,648	357,037
Securitization Vehicles | CDOs & Other
Impairment previously recorded in other comprehensive income
Number of investments	4	1
Estimated Fair Value	18,600	1,900
Securities held-to-maturity	$ 30,200	$ 1,935

[1] Includes securities with a total face value of $236.4 million and $490.9 million as of September 30, 2012 and December 31, 2011, respectively.