Derivative Instruments And Hedging Activities (Notional Values Of Derivative Contracts Designated And Not Designated As Hedging Instruments) (Details) - USD ($) $ in Millions	Feb. 28, 2016	May. 31, 2015
Designated as Hedging Instruments | Equity forwards
Derivatives, Fair Value [Line Items]
Derivative contracts, notional	$ 17.2	$ 11.4
Designated as Hedging Instruments | Interest rate related
Derivatives, Fair Value [Line Items]
Derivative contracts, notional	0.0	200.0
Not Designated as Hedging Instruments | Equity forwards
Derivatives, Fair Value [Line Items]
Derivative contracts, notional	$ 30.2	$ 51.7