Accumulated Other Comprehensive Income (Loss) (Changes in Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Aug. 31, 2014	Aug. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at June 1, 2014	$ 28,428	$ 38,123
Other comprehensive (loss) income before reclassifications	(2,098)	(660)
Amounts reclassified from accumulated other comprehensive income (loss)	488	488
Other comprehensive loss	(1,610)	(172)
Balance at August 31, 2014	26,818	37,951
Foreign Currency
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at June 1, 2014	41,525	51,312
Other comprehensive (loss) income before reclassifications	(2,115)	(646)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Other comprehensive loss	(2,115)	(646)
Balance at August 31, 2014	39,410	50,666
Unrealized Loss on Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at June 1, 2014	(12,615)	(14,339)
Other comprehensive (loss) income before reclassifications	17	0
Amounts reclassified from accumulated other comprehensive income (loss)	488	488
Other comprehensive loss	505	488
Balance at August 31, 2014	(12,110)	(13,851)
Other
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at June 1, 2014	(482)	1,150
Other comprehensive (loss) income before reclassifications	0	(14)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Other comprehensive loss	0	(14)
Balance at August 31, 2014	$ (482)	$ 1,136