Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015	May. 31, 2015
Income Tax Disclosure [Abstract]
Provision for income tax	$ 2,613,000	$ 99,379,000	$ 80,564,000	$ 174,512,000
Federal statutory rate	35.00%	35.00%	35.00%	35.00%
Net discrete tax benefits primarily comprised of reversal of deferred tax asset valuation allowances and adjustments to tax contingency reserves	$ 3,900,000	$ 13,100,000
Provision for deferred income taxes	0	106,200,000	$ 0	$ 106,200,000
Undistributed foreign earnings	356,500,000	$ 347,500,000	356,500,000	$ 347,500,000	$ 419,100,000
Deferred income tax liability	$ 91,600,000		$ 91,600,000		$ 108,500,000