Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2016	May 31, 2015	May 31, 2014
AOCI, Net of Tax [Roll Forward]
Beginning Balance	$ 1,932,455	$ 2,192,858	$ 2,201,492
Other comprehensive loss	(16,403)	(36,899)	(9,695)
Ending Balance	1,842,659	1,932,455	2,192,858
Foreign Currency
AOCI, Net of Tax [Roll Forward]
Beginning Balance	2,987	41,525
Other comprehensive loss before reclassifications	(11,933)	(38,538)
Amounts reclassified from accumulated other comprehensive income (loss)	6,472	0
Other comprehensive loss	(5,461)	(38,538)
Ending Balance	(2,474)	2,987	41,525
Unrealized Loss on Derivatives
AOCI, Net of Tax [Roll Forward]
Beginning Balance	(10,626)	(12,615)
Other comprehensive loss before reclassifications	(12,156)	37
Amounts reclassified from accumulated other comprehensive income (loss)	1,952	1,952
Other comprehensive loss	(10,204)	1,989
Ending Balance	(20,830)	(10,626)	(12,615)
Other
AOCI, Net of Tax [Roll Forward]
Beginning Balance	(832)	(482)
Other comprehensive loss before reclassifications	(738)	(350)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Other comprehensive loss	(738)	(350)
Ending Balance	(1,570)	(832)	(482)
Other Accumulated Comprehensive Income (Loss)
AOCI, Net of Tax [Roll Forward]
Beginning Balance	(8,471)	28,428	38,123
Other comprehensive loss before reclassifications	(24,827)	(38,851)
Amounts reclassified from accumulated other comprehensive income (loss)	8,424	1,952
Other comprehensive loss	(16,403)	(36,899)
Ending Balance	$ (24,874)	$ (8,471)	$ 28,428