Goodwill, Service Contracts and Other Assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2017	Nov. 30, 2016
Goodwill, Service Contracts and Other Assets [Abstract]
Amortization expense for service contracts and other assets	$ 15.6	$ 3.2	$ 29.8	$ 6.4
Estimated amortization expense, year one	61.3		61.3
Estimated amortization expense, year two	61.0		61.0
Estimated amortization expense, year three	59.6		59.6
Estimated amortization expense, year four	53.8		53.8
Estimated amortization expense, year five	51.8		51.8
Estimated amortization expense, thereafter	$ 248.3		$ 248.3