Summary of Significant Accounting Policies - Intangibles (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2020	May 31, 2019	May 31, 2018	Jun. 01, 2019
Amortizable intangible assets:
Gross carrying amount		$ 51.4
Accumulated Amortization	$ (16.5)	(30.3)
Net carrying amount		21.1
Unamortized intangible assets:
Trademarks	1.1	1.1
Intangible Assets, Gross (Excluding Goodwill)	22.5	52.5
Intangible Assets, Net (Excluding Goodwill), Total	6.0	22.2		$ 13.7
Impairment charge related to exit of certain product line	5.4
Amortization expense	2.3	3.9	$ 4.7
Estimated aggregate amortization expense for intangible assets in each of the next five fiscal years
2021	1.7
2022	1.0
2023	0.5
2024	0.3
2025	0.3
Customer relationships
Amortizable intangible assets:
Gross carrying amount	21.4	25.5
Accumulated Amortization	(16.5)	(15.6)
Net carrying amount	$ 4.9	9.9
Lease agreements
Amortizable intangible assets:
Gross carrying amount		22.5
Accumulated Amortization		(14.0)
Net carrying amount		8.5
Other
Amortizable intangible assets:
Gross carrying amount		3.4
Accumulated Amortization		(0.7)
Net carrying amount		$ 2.7
Minimum | Customer relationships
Unamortized intangible assets:
Useful life	5 years
Maximum | Customer relationships
Unamortized intangible assets:
Useful life	20 years