Securitization Activities - Summary of Retained Interests in SPEs (Detail) - USD ($) $ in Millions	Nov. 30, 2017	Nov. 30, 2016
Securitization Vehicles [Line Items]
Total RMBS securitization assets	$ 6,383.5	$ 7,584.9
Total CMBS securitization assets	2,075.7	1,806.3
Total Collateralized loan obligations	3,957.8	4,102.2
Consumer and other loans	247.6	395.7
U.S. government agency RMBS
Securitization Vehicles [Line Items]
Retained Interests	28.2	31.0
U.S. government agency CMBS
Securitization Vehicles [Line Items]
Retained Interests	81.4	29.6
CLOs
Securitization Vehicles [Line Items]
Retained Interests	20.3	37.0
Consumer and other loans
Securitization Vehicles [Line Items]
Retained Interests	$ 47.8	$ 25.3