Accumulated Other Comprehensive Income (Loss) (Changes in Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Feb. 28, 2014	Nov. 30, 2013	Aug. 31, 2013	Feb. 28, 2013	Feb. 28, 2014	Feb. 28, 2013
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	$ 40,286	$ 37,951	$ 38,123		$ 38,123
Other comprehensive income (loss) before reclassifications	(5,222)	1,847	(660)
Amounts reclassified from accumulated other comprehensive income (loss)	488	488	488
Other comprehensive (loss) income	(4,734)	2,335	(172)	(7,720)	(2,571)	1,785
Ending balance	35,552	40,286	37,951		35,552
Foreign Currency
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	52,706	50,666	51,312		51,312
Other comprehensive income (loss) before reclassifications	(5,121)	2,040	(646)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0
Other comprehensive (loss) income	(5,121)	2,040	(646)
Ending balance	47,585	52,706	50,666		47,585
Unrealized Loss on Derivatives
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(13,552)	(13,851)	(14,339)		(14,339)
Other comprehensive income (loss) before reclassifications	(102)	(189)	0
Amounts reclassified from accumulated other comprehensive income (loss)	488	488	488
Other comprehensive (loss) income	386	299	488
Ending balance	(13,166)	(13,552)	(13,851)		(13,166)
Other
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	1,132	1,136	1,150		1,150
Other comprehensive income (loss) before reclassifications	1	(4)	(14)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0
Other comprehensive (loss) income	1	(4)	(14)
Ending balance	$ 1,133	$ 1,132	$ 1,136		$ 1,133