Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Nov. 30, 2015	Nov. 30, 2014	Nov. 30, 2015	Nov. 30, 2014	May. 31, 2015
Income Tax Disclosure [Abstract]
Effective income tax rate	30.00%	30.20%	29.70%	29.60%
Federal statutory rate	35.00%	35.00%
Undistributed foreign earnings	$ 401,500,000		$ 401,500,000		$ 419,100,000
Deferred income tax liability	101,900,000		101,900,000		$ 108,500,000
Provision for deferred income taxes	$ 0		$ 0