Goodwill, Service Contracts and Other Assets - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2018	Aug. 31, 2017
Goodwill, Service Contracts and Other Assets [Abstract]
Amortization expense for service contracts and other assets	$ 33.0	$ 14.1
Estimated amortization expense, year one	131.6
Estimated amortization expense, year two	121.1
Estimated amortization expense, year three	106.1
Estimated amortization expense, year four	94.3
Estimated amortization expense, year five	76.3
Estimated amortization expense, thereafter	$ 313.7