Derivative Financial Instruments - External Credit Ratings of Underlyings or Referenced Assets (Details) - USD ($) $ in Millions	Aug. 31, 2019	Nov. 30, 2018
Index credit default swaps
Derivative [Line Items]
Total Notional	$ 96.8	$ 193.1
Single name credit default swaps
Derivative [Line Items]
Total Notional	72.1	145.2
Investment Grade | Index credit default swaps
Derivative [Line Items]
Total Notional	0.0	25.7
Investment Grade | Single name credit default swaps
Derivative [Line Items]
Total Notional	7.6	57.7
Non-investment Grade | Index credit default swaps
Derivative [Line Items]
Total Notional	96.8	167.4
Non-investment Grade | Single name credit default swaps
Derivative [Line Items]
Total Notional	31.6	84.5
Unrated | Index credit default swaps
Derivative [Line Items]
Total Notional	0.0	0.0
Unrated | Single name credit default swaps
Derivative [Line Items]
Total Notional	$ 32.9	$ 3.0