Securitization Activities - Summary of Retained Interests in SPEs (Details) - USD ($) $ in Millions	Nov. 30, 2020	Nov. 30, 2019
Securitization Vehicles [Line Items]
Total RMBS securitization assets	$ 562.5	$ 10,671.7
Total CMBS securitization assets	2,461.2	1,374.8
Total collateralized loan obligations	3,345.5	3,006.7
Consumer and other loans	1,290.6	1,149.3
U.S. government agency RMBS
Securitization Vehicles [Line Items]
Retained Interests	7.8	103.3
U.S. government agency CMBS
Securitization Vehicles [Line Items]
Retained Interests	205.2	45.8
CLOs
Securitization Vehicles [Line Items]
Retained Interests	39.5	58.4
Consumer and other loans
Securitization Vehicles [Line Items]
Retained Interests	$ 56.6	$ 71.8