Derivative Financial Instruments - External Credit Ratings of Underlyings or Referenced Assets (Details) - USD ($) $ in Millions	Aug. 31, 2020	Nov. 30, 2019
Index credit default swaps
Derivative [Line Items]
Derivative notional amount	$ 47.9	$ 35.0
Single name credit default swaps
Derivative [Line Items]
Derivative notional amount	6.4	33.9
Investment Grade | Index credit default swaps
Derivative [Line Items]
Derivative notional amount	2.0	3.0
Investment Grade | Single name credit default swaps
Derivative [Line Items]
Derivative notional amount	0.0	3.4
Non-investment Grade | Index credit default swaps
Derivative [Line Items]
Derivative notional amount	45.9	32.0
Non-investment Grade | Single name credit default swaps
Derivative [Line Items]
Derivative notional amount	6.2	29.0
Unrated | Index credit default swaps
Derivative [Line Items]
Derivative notional amount	0.0	0.0
Unrated | Single name credit default swaps
Derivative [Line Items]
Derivative notional amount	$ 0.2	$ 1.5