CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2015	Aug. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (49.4)	$ (34.1)
Other comprehensive income (loss), net:
Foreign currency translation adjustments	(7.3)	0.5
Pension and post-retirement adjustments (net of tax)	0.7	0.5
Total other comprehensive income (loss)	(6.6)	1.0
Comprehensive income (loss)	$ (56.0)	$ (33.1)