Discontinued Operations - Schedule of Discontinued Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	May. 31, 2015	May. 31, 2014	May. 31, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax (benefit) expense	$ 12,320	$ 658	$ 377
Gain on sale of business	38,573	0	0
Net income (loss) from discontinued operations	22,541	157	(1,144)
Discontinued Operations | Storage Business
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue	31,379	82,246	70,507
(Loss) income before income taxes	(3,712)	815	(767)
Income tax (benefit) expense	(3,232)	658	377
Gain on sale of business	38,573	0	0
Income tax expense on gain	15,552	0	0
Net income (loss) from discontinued operations	$ 22,541	$ 157	$ (1,144)