Securitization Activities - Summary of Retained Interests in SPEs (Details) - USD ($) $ in Millions	Aug. 31, 2020	Nov. 30, 2019
Debt and Equity Securities, FV-NI [Line Items]
Total RMBS securitization assets	$ 928.7	$ 10,671.7
Total CMBS securitization assets	439.2	1,374.8
Total Collateralized loan obligations	3,419.9	3,006.7
Consumer and other loans	884.0	1,149.3
U.S. government agency RMBS
Debt and Equity Securities, FV-NI [Line Items]
Retained Interests	12.4	103.3
U.S. government agency CMBS
Debt and Equity Securities, FV-NI [Line Items]
Retained Interests	138.3	45.8
CLOs
Debt and Equity Securities, FV-NI [Line Items]
Retained Interests	41.8	58.4
Consumer and other loans
Debt and Equity Securities, FV-NI [Line Items]
Retained Interests	$ 45.6	$ 71.8