CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2017	Nov. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 57.1	$ 67.9	$ (6.6)	$ 28.3
Other comprehensive income (loss), net:
Foreign currency translation adjustments	0.1	(5.1)	3.8	(7.0)
Pension and post-retirement adjustments (net of tax)	9.0	0.7	9.5	1.4
Total other comprehensive income (loss)	9.1	(4.4)	13.3	(5.6)
Comprehensive income (loss)	$ 66.2	$ 63.5	$ 6.7	$ 22.7