Goodwill, Service Contracts and Other Assets - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 2,846,888	$ 2,782,335	$ 1,276,076
Service contracts
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Weighted average amortization period	12 years 9 months 18 days
Noncompete and consulting agreements
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Weighted average amortization period	5 years
Consulting Agreements and Other
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Weighted average amortization period	4 years
Continuing Operations
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 61,200	22,800	$ 14,200
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Estimated amortization expense, year one	62,500
Estimated amortization expense, year two	61,100
Estimated amortization expense, year three	55,200
Estimated amortization expense, year four	53,200
Estimated amortization expense, year five	44,900
Estimated amortization expense, thereafter	$ 283,400
Discontinued Operations, Held-for-sale
Finite-Lived Intangible Assets [Line Items]
Goodwill		$ 15,500