Derivative Financial Instruments - External Credit Ratings of Underlyings or Referenced Assets (Details) - USD ($) $ in Millions	Nov. 30, 2017	Nov. 30, 2016
Index credit default swaps
Derivative [Line Items]
Notional amount	$ 49.0	$ 54.0
Single name credit default swaps
Derivative [Line Items]
Notional amount	218.2	383.6
Investment Grade | Index credit default swaps
Derivative [Line Items]
Notional amount	3.0	54.0
Investment Grade | Single name credit default swaps
Derivative [Line Items]
Notional amount	129.1	122.4
Non-investment Grade | Index credit default swaps
Derivative [Line Items]
Notional amount	46.0	0.0
Non-investment Grade | Single name credit default swaps
Derivative [Line Items]
Notional amount	$ 89.1	$ 261.2