Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Nov. 30, 2014	Aug. 31, 2014	Nov. 30, 2013	Aug. 31, 2013	Nov. 30, 2014	Nov. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ 26,818	$ 28,428	$ 37,951	$ 38,123	$ 28,428	$ 38,123
Other comprehensive (loss) income before reclassifications	(9,796)	(2,098)	1,847	(660)
Amounts reclassified from accumulated other comprehensive income (loss)	488	488	488	488
Other comprehensive (loss) income	(9,308)	(1,610)	2,335	(172)	(10,918)	2,163
Ending Balance	17,510	26,818	40,286	37,951	17,510	40,286
Foreign Currency
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	39,410	41,525	50,666	51,312	41,525	51,312
Other comprehensive (loss) income before reclassifications	(9,778)	(2,115)	2,040	(646)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Other comprehensive (loss) income	(9,778)	(2,115)	2,040	(646)
Ending Balance	29,632	39,410	52,706	50,666	29,632	52,706
Unrealized Loss on Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(12,110)	(12,615)	(13,851)	(14,339)	(12,615)	(14,339)
Other comprehensive (loss) income before reclassifications	(21)	17	(189)	0
Amounts reclassified from accumulated other comprehensive income (loss)	488	488	488	488
Other comprehensive (loss) income	467	505	299	488
Ending Balance	(11,643)	(12,110)	(13,552)	(13,851)	(11,643)	(13,552)
Other
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(482)	(482)	1,136	1,150	(482)	1,150
Other comprehensive (loss) income before reclassifications	3	0	(4)	(14)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0	0
Other comprehensive (loss) income	3	0	(4)	(14)
Ending Balance	$ (479)	$ (482)	$ 1,132	$ 1,136	$ (479)	$ 1,132