CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2017	Aug. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (63.7)	$ (39.6)
Other comprehensive income (loss), net:
Foreign currency translation adjustments	3.7	(1.9)
Pension and post-retirement adjustments (net of tax)	0.5	0.7
Total other comprehensive income (loss)	4.2	(1.2)
Comprehensive income (loss)	$ (59.5)	$ (40.8)