Accumulated Other Comprehensive Income (Loss) - Tax effects in other comprehensive income (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Nov. 30, 2014	Nov. 30, 2013	Nov. 30, 2014	Nov. 30, 2013
Equity [Abstract]
Unrecognized actuarial gains (losses), before tax	$ 2.3	$ (0.2)	$ 2.7	$ 0
Unrecognized actuarial gains (losses), tax	(0.7)	0	(0.8)	0
Unrecognized actuarial gains (losses), net of tax	1.6	(0.2)	1.9	0
Foreign currency translation adjustments, before tax	(152.0)	26.0	(203.8)	18.2
Foreign currency translation adjustments, tax	14.7	1.2	18.3	13.5
Foreign currency translation adjustments, net tax	(137.3)	27.2	(185.5)	31.7
Unrealized gain (loss) on interest rate swaps, before tax	(2.7)	(18.1)	(5.7)	(9.4)
Unrealized gain (loss) on interest rate swaps, tax	0.7	9.1	4.3	9.3
Unrealized gain (loss) on interest rate swaps, net of tax	(2.0)	(9.0)	(1.4)	(0.1)
Reclassifications on interest rate swaps, before tax	2.5	28.6	7.3	36.1
Reclassifications on interest rate swaps, tax	(0.9)	(10.8)	(2.7)	(13.7)
Reclassifications on interest rate swaps, net of tax	1.6	17.8	4.6	22.4
Unrealized gain (loss) on available-for-sale securities, before tax	0	2.7	0.1	2.7
Unrealized gain (loss) on available-for-sale securities, tax	0	(1.4)	0	(1.4)
Unrealized gain (loss) on available-for-sale securities, net of tax	0	1.3	0.1	1.3
Accumulated other comprehensive income, before tax	(149.9)	39.0	(199.4)	47.6
Accumulated other comprehensive income, tax	13.8	(1.9)	19.1	7.7
Other comprehensive income (loss)	$ (136.1)	$ 37.1	$ (180.3)	$ 55.3