Securitization Activities (Details 1) (USD $)	11 Months Ended	12 Months Ended
	Nov. 30, 2010	Nov. 30, 2011	Nov. 30, 2010
Summary of retained interests in SPEs
Total RMBS securitization assets	$ 6,549,500,000	$ 7,968,000,000	$ 6,549,500,000
Total CMBS securitization assets	2,005,400,000	2,574,300,000	2,005,400,000
Military housing loans	107,800,000	127,400,000	107,800,000
Assets Retained	87,000	347,000	100,000
Current year securities [Member]
Securitization Activities (Textual) [Abstract]
Inventory in residential mortgage-backed securities		248,300,000
Inventory in Commercial mortgage-backed securities		27,600,000
Previous year securities [Member]
Securitization Activities (Textual) [Abstract]
Inventory in residential mortgage-backed securities		30,200,000
Inventory in Commercial mortgage-backed securities		27,600,000
U.S. government agency residential mortgage-backed securities [Member]
Summary of retained interests in SPEs
Fair Value of Mortgage-Backed Securitizations Initially Retained	684,700,000	517,900,000	684,700,000
U.S. government agency commercial mortgage-backed securities [Member]
Summary of retained interests in SPEs
Fair Value of Mortgage-Backed Securitizations Initially Retained	$ 40,400,000	$ 49,900,000	$ 40,400,000