Variable Interest Entities - Variable Interests in Non-Consolidated Variable Interest Entities (Detail) - Nonconsolidated VIEs - USD ($) $ in Millions	Aug. 31, 2017	Nov. 30, 2016
Variable Interest Entity [Line Items]
Carrying Amount, Assets	$ 334.0	$ 443.5
Carrying Amount, Liabilities	1.9	4.8
Maximum Exposure to Loss	1,655.3	1,257.0
VIE Assets	9,061.6	9,467.5
CLOs
Variable Interest Entity [Line Items]
Carrying Amount, Assets	58.1	263.3
Carrying Amount, Liabilities	1.9	4.8
Maximum Exposure to Loss	790.1	920.0
VIE Assets	3,440.3	4,451.7
Consumer loan vehicles
Variable Interest Entity [Line Items]
Carrying Amount, Assets	195.8	90.3
Carrying Amount, Liabilities	0.0	0.0
Maximum Exposure to Loss	761.9	219.6
VIE Assets	2,287.2	985.5
Related party private equity vehicles
Variable Interest Entity [Line Items]
Carrying Amount, Assets	28.1	37.6
Carrying Amount, Liabilities	0.0	0.0
Maximum Exposure to Loss	49.8	63.6
VIE Assets	106.3	155.6
Other private investment vehicles
Variable Interest Entity [Line Items]
Carrying Amount, Assets	52.0	52.3
Carrying Amount, Liabilities	0.0	0.0
Maximum Exposure to Loss	53.5	53.8
VIE Assets	$ 3,227.8	$ 3,874.7