Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2018	May 31, 2017
Income Tax And Non Income Tax Disclosure [Abstract]
Settlements during the period	$ 0.2	$ 0.2	$ 1.9
Decrease in deferred tax asset valuation allowance	(5.6)	(0.6)
Valuation Allowance, Deferred Tax Asset, Decrease, Valuation Amount		3.9
Valuation Allowance, Deferred Tax Asset, Decrease, Releases Amount		3.3
Unrecognized tax benefits	10.2	9.0	10.1	$ 14.1
Income tax penalties and interest accrued	2.2	1.4	1.8
Unrecognized tax benefits that would impact effective tax rate	10.2	9.0	10.1
Tax (expense) benefit from income tax penalties and interest expense	0.8	(0.4)	(0.1)
Period increase (decrease) in unrecognized tax benefits	(1.2)	(1.1)
Loss Contingencies [Line Items]
Deferred Tax Assets, Net	12.3	37.0
Deferred Tax Liabilities, Net	92.3	60.5
Tax Cuts and Jobs Act, Global Intangible Low-Taxed Income, Income Tax Expense		0.9
Operating Loss Carryforwards, Valuation Allowance	15.4	28.1
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest			(1.5)
Earnings (loss) before income taxes	(89.7)	26.0	(1.5)
Settlement charge			57.3
Remeasurement expense			5.7
Provision (benefit) for income taxes	(46.0)	$ 10.4	$ 3.5
Other Noncurrent Liabilities [Member]
Loss Contingencies [Line Items]
Deferred Tax Assets, Net	18.6
Deferred Tax Liabilities, Net	$ 6.3