Goodwill and Other Intangibles - Schedule of other intangible assets subject to amortization (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Nov. 30, 2019	Nov. 30, 2018	May 31, 2018	May 31, 2014	May 31, 2019
Finite-lived Intangible Assets [Roll Forward]
Beginning balance other intangibles subject to amortization	$ 12.2		$ 10.1
Additions	0.0	$ 0.6	4.5
Amortization expense	(1.5)	(1.3)	(2.8)
Foreign currency translation	0.0	(0.1)	$ (0.2)
Other	0.0	0.0		$ 0.6
Total other intangibles subject to amortization, net of accumulated amortization of $24.8, $24.1 and $22.5, respectively	10.7	9.3
Accumulated amortization of intangible assets	28.4	25.4			$ 26.9
Total other intangibles not subject to amortization	2.1	2.1			2.1
Total other intangibles	$ 12.8	$ 11.4			$ 14.3