Goodwill, Service Contracts and Other Assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2017	Aug. 31, 2016
Goodwill, Service Contracts and Other Assets [Abstract]
Amortization expense for service contracts and other assets	$ 14.1	$ 3.2
Estimated amortization expense, year one	61.4
Estimated amortization expense, year two	60.9
Estimated amortization expense, year three	59.5
Estimated amortization expense, year four	53.7
Estimated amortization expense, year five	$ 51.7