Goodwill and Other Intangibles - Schedule of other intangible assets subject to amortization (Details) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Feb. 28, 2019	Feb. 28, 2018	May 31, 2018
Finite-lived Intangible Assets [Roll Forward]
Beginning balance other intangibles subject to amortization	$ 10.1	$ 9.0	$ 9.0
Additions	0.6	1.5	3.3
Amortization expense	(2.0)	(1.6)	(2.1)
Foreign currency translation	0.0	0.1	(0.1)
Total other intangibles subject to amortization, net of accumulated amortization of $24.8, $24.1 and $22.5, respectively	8.7	9.0	10.1
Accumulated amortization of intangible assets	26.1	23.6	24.1
Total other intangibles not subject to amortization	2.1	2.1	2.1
Total other intangibles	$ 10.8	$ 11.1	$ 12.2