Variable Interest Entities - Variable Interests in Non-Consolidated Variable Interest Entities (Detail) - Nonconsolidated VIEs - USD ($) $ in Millions	Feb. 28, 2018	Nov. 30, 2017
Variable Interest Entity [Line Items]
Carrying Amount, Assets	$ 607.1	$ 490.0
Carrying Amount, Liabilities	4.9	8.9
Maximum Exposure to Loss	2,076.9	1,874.4
VIE Assets	11,554.5	10,546.5
CLOs
Variable Interest Entity [Line Items]
Carrying Amount, Assets	212.3	163.5
Carrying Amount, Liabilities	4.9	8.9
Maximum Exposure to Loss	1,247.6	1,020.5
VIE Assets	5,342.6	5,210.4
Consumer loan vehicles
Variable Interest Entity [Line Items]
Carrying Amount, Assets	315.8	254.8
Carrying Amount, Liabilities	0.0	0.0
Maximum Exposure to Loss	728.0	759.8
VIE Assets	2,879.6	2,322.7
Related party private equity vehicles
Variable Interest Entity [Line Items]
Carrying Amount, Assets	30.9	23.7
Carrying Amount, Liabilities	0.0	0.0
Maximum Exposure to Loss	52.4	45.4
VIE Assets	97.1	75.0
Other private investment vehicles
Variable Interest Entity [Line Items]
Carrying Amount, Assets	48.1	48.0
Carrying Amount, Liabilities	0.0	0.0
Maximum Exposure to Loss	48.9	48.7
VIE Assets	$ 3,235.2	$ 2,938.4