Derivative Financial Instruments (Credit Related Derivative Contracts) (Details) - USD ($) $ in Millions	Feb. 28, 2019	Nov. 30, 2018
Index credit default swaps
Derivative [Line Items]
Notional amount	$ 190.5	$ 193.1
Single name credit default swaps
Derivative [Line Items]
Notional amount	94.9	145.2
Investment Grade | Index credit default swaps
Derivative [Line Items]
Notional amount	90.5	25.7
Investment Grade | Single name credit default swaps
Derivative [Line Items]
Notional amount	8.4	57.7
Non-investment grade | Index credit default swaps
Derivative [Line Items]
Notional amount	100.0	167.4
Non-investment grade | Single name credit default swaps
Derivative [Line Items]
Notional amount	53.9	84.5
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	$ 32.6	$ 3.0