CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2018	Feb. 28, 2017	Feb. 28, 2018	Feb. 28, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (49.2)	$ (15.4)	$ (55.8)	$ 12.9
Other comprehensive income (loss), net:
Foreign currency translation adjustments (net of tax)	2.2	0.9	6.0	(6.1)
Pension and post-retirement adjustments (net of tax)	22.2	0.7	31.7	2.1
Total other comprehensive income (loss), net	24.4	1.6	37.7	(4.0)
Comprehensive income (loss)	$ (24.8)	$ (13.8)	$ (18.1)	$ 8.9