Accumulated Other Comprehensive Income (Loss) (Changes in Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	May 31, 2014	May 31, 2013	May 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 38,123
Other comprehensive loss before reclassifications	(11,647)
Amounts reclassified from accumulated other comprehensive income (loss)	1,952
Net current period other comprehensive (loss) income	(9,695)	1,460	(22,144)
Ending Balance	28,428	38,123
Foreign Currency [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	51,312
Other comprehensive loss before reclassifications	(9,787)
Amounts reclassified from accumulated other comprehensive income (loss)	0
Net current period other comprehensive (loss) income	(9,787)
Ending Balance	41,525
Unrealized Loss on Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(14,339)
Other comprehensive loss before reclassifications	(228)
Amounts reclassified from accumulated other comprehensive income (loss)	1,952
Net current period other comprehensive (loss) income	1,724
Ending Balance	(12,615)
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	1,150
Other comprehensive loss before reclassifications	(1,632)
Amounts reclassified from accumulated other comprehensive income (loss)	0
Net current period other comprehensive (loss) income	(1,632)
Ending Balance	$ (482)