Accumulated Other Comprehensive Income (Loss) - Accumulated Other Comprehensive Income (Loss) and Related Component (Detail) (USD $) In Millions, unless otherwise specified	Aug. 31, 2012	May 31, 2012
Accumulated Other Comprehensive Income Loss [Line Items]
Unrealized loss on available-for-sale securities, net of tax	$ 0.3	$ (0.5)
Unrealized gain (loss) on interest rate swaps, net of tax	(49.9)	(47.3)
Foreign currency translation adjustments	196.9	173.7
Unrecognized actuarial gain (loss) on pension assets, net of tax	(3.0)	(3.0)
Accumulated other comprehensive income	$ 144.3	$ 122.9