- Schedule of other intangible assets subject to amortization (Details) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Feb. 28, 2018	Feb. 28, 2017	May 31, 2016	May 31, 2017
Finite-lived Intangible Assets [Roll Forward]
Beginning balance other intangibles subject to amortization	$ 9.0	$ 4.7
Additions	1.5	0.2	$ 7.0
Amortization expense	(1.6)	(1.8)	(2.5)
Foreign currency translation	0.1	(0.2)	(0.2)
Total other intangibles subject to amortization, net of accumulated amortization of $23.6, $22.0 and $21.3, respectively	9.0	2.9	$ 4.7
Accumulated amortization of intangible assets	23.6	21.3		$ 22.0
Total other intangibles not subject to amortization	2.1	2.1		2.1
Total other intangibles	$ 11.1	$ 5.0		$ 11.1