Accumulated Other Comprehensive Income (Loss) - Reclassifications Out of Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Nov. 30, 2015	Aug. 31, 2015	Nov. 30, 2014	Aug. 31, 2014	Nov. 30, 2015	Nov. 30, 2014
Equity [Abstract]
Amortization of interest rate locks	$ (783)		$ (783)		$ (1,565)	$ (1,565)
Amortization of interest rate locks, net of tax	(488)		(488)		(976)	(976)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax benefit	295		295		589	589
Cumulative translation adjustment on investment in Shred-it, net of tax	(6,960)	$ (488)	(488)	$ (488)
Accumulated Translation Adjustment on Investment Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cumulative translation adjustment on investment in Shred-it	(10,381)		0		(10,381)	0
Tax benefit	3,909		0		3,909	0
Cumulative translation adjustment on investment in Shred-it, net of tax	$ (6,472)		$ 0		$ (6,472)	$ 0