Summary of Significant Accounting Policies - Contract Assets and Liabilities and Remaining Performance Obligations (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Aug. 31, 2021	May 31, 2021	May 31, 2020	May 31, 2019	May 31, 2018
Contract Assets and Liabilities
Contract assets - current		$ 71.9	$ 49.3
Contract assets - non-current		21.6	22.4
Contract liabilities - current		(25.9)	(11.2)
Deferred revenue on long-term contracts		(5.4)	(88.0)
Net contract assets (liabilities)		62.2	(27.5)
Change in contract assets - current		22.6
Change in contract assets - non-current		(0.8)
Change in contract liabilities - current		(14.7)
Change in contract liabilities - non-current		82.6
Change in net contract assets (liabilities)		89.7
Forward loss reserves		16.4	22.1	$ 16.0	$ 7.5
PBH forward loss reserve		3.0
Change in Contract with Customer, Liability
Deferred revenue at beginning of period	$ (31.3)	(99.2)	(96.4)
Revenue deferred		(251.4)	(417.2)
Revenue recognized		(318.2)	(410.5)
Other		1.1	3.9
Deferred revenue at end of period		(31.3)	(99.2)
Remaining Performance Obligations
Remaining performance obligation		$ 750,000.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-06-01
Remaining Performance Obligations
Remaining performance obligation (as a percent)		40.00%
Expected timing of satisfaction of remaining performance obligation		12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-06-01
Remaining Performance Obligations
Remaining performance obligation (as a percent)		45.00%
Expected timing of satisfaction of remaining performance obligation		3 years
Accrued liabilities
Contract Assets and Liabilities
PBH forward loss reserve		$ 2.8
Other liabilities
Contract Assets and Liabilities
PBH forward loss reserve		0.2
PBH contracts
Contract Assets and Liabilities
Contract Charges on non-achievement of minimum volume guarantees		4.5
Customer contract termination and restructuring costs		5.7	$ 31.3
PBH forward loss reserve		2.9
PBH contracts | Accrued liabilities
Contract Assets and Liabilities
PBH forward loss reserve		1.5
PBH contracts | Other liabilities
Contract Assets and Liabilities
PBH forward loss reserve		$ 1.4
PBH contracts | Minimum | Forecast
Contract Assets and Liabilities
Customer contract termination and restructuring costs	5.0
PBH contracts | Maximum | Forecast
Contract Assets and Liabilities
Customer contract termination and restructuring costs	$ 10.0