Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Aug. 31, 2015	Aug. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	$ (8,471)	$ 28,428
Other comprehensive loss before reclassifications	(12,021)	(2,098)
Amounts reclassified from accumulated other comprehensive income (loss)	488	488
Other comprehensive loss	(11,533)	(1,610)
Ending Balance	(20,004)	26,818
Foreign Currency
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	2,987	41,525
Other comprehensive loss before reclassifications	(12,013)	(2,115)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Other comprehensive loss	(12,013)	(2,115)
Ending Balance	(9,026)	39,410
Unrealized Loss on Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(10,626)	(12,615)
Other comprehensive loss before reclassifications	0	17
Amounts reclassified from accumulated other comprehensive income (loss)	488	488
Other comprehensive loss	488	505
Ending Balance	(10,138)	(12,110)
Other
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(832)	(482)
Other comprehensive loss before reclassifications	(8)	0
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Other comprehensive loss	(8)	0
Ending Balance	$ (840)	$ (482)