Derivative Financial Instruments (Credit Related Derivative Contracts) (Details) - USD ($) $ in Millions	Feb. 29, 2020	Nov. 30, 2019
Index credit default swaps
Derivative [Line Items]
Notional amount	$ 293.0	$ 35.0
Single name credit default swaps
Derivative [Line Items]
Notional amount	25.7	33.9
Investment Grade | Index credit default swaps
Derivative [Line Items]
Notional amount	2.0	3.0
Investment Grade | Single name credit default swaps
Derivative [Line Items]
Notional amount	17.8	3.4
Non-investment grade | Index credit default swaps
Derivative [Line Items]
Notional amount	291.0	32.0
Non-investment grade | Single name credit default swaps
Derivative [Line Items]
Notional amount	7.9	29.0
Unrated | Index credit default swaps
Derivative [Line Items]
Notional amount	0.0	0.0
Unrated | Single name credit default swaps
Derivative [Line Items]
Notional amount	$ 0.0	$ 1.5