Summary of Significant Accounting Policies - Intangibles (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2021	May 31, 2020	May 31, 2019	Jun. 01, 2019
Amortizable intangible assets:
Accumulated Amortization	$ (19.7)	$ (16.5)
Unamortized intangible assets:
Trademarks	1.2	1.1
Intangible Assets, Gross (Excluding Goodwill)	24.2	22.5
Intangible Assets, Net (Excluding Goodwill), Total	4.5	6.0
Impairment charge related to exit of certain product line		5.4
Amortization expense	1.8	2.3	$ 3.9
Estimated aggregate amortization expense for intangible assets in each of the next five fiscal years
2022	1.1
2023	0.5
2024	0.3
2025	0.3
2026	0.3
Customer relationships
Amortizable intangible assets:
Gross carrying amount	23.0	21.4
Accumulated Amortization	(19.7)	(16.5)
Net carrying amount	$ 3.3	$ 4.9
Minimum | Customer relationships
Unamortized intangible assets:
Useful life	5 years
Maximum | Customer relationships
Unamortized intangible assets:
Useful life	20 years
ASC 842
Unamortized intangible assets:
Net intangible asset for lease agreements reclassified to ROU asset				$ 8.5