Derivative Instruments and Hedging Activities - Schedule of Interest Rate Swap (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 9 Months Ended
Feb. 28, 2014
Feb. 28, 2013
Feb. 28, 2014
Feb. 28, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]        
Amount of gain (loss) recognized in OCI $ 5.5 $ 10.7 $ 31.7 $ 9.5
Amount of (gain) loss reclassified from accumulated OCI into interest expense (effective portion) 6.2 9.0 20.5 40.4
Amount (gain) loss recognized in other income (expense) (ineffective portion and amount excluded from effectiveness testing)       $ 21.8