Consolidated Condensed Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Aug. 31, 2015	Aug. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 100,181	$ 110,108
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustments	(12,013)	(2,115)
Change in fair value of derivatives	0	17
Amortization of interest rate lock agreements	488	488
Change in fair value of available-for-sale securities	(8)	0
Other comprehensive loss	(11,533)	(1,610)
Comprehensive income	$ 88,648	$ 108,498