STOCK-BASED COMPENSATION - Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended
Aug. 25, 2019	Aug. 26, 2018
Compensation expense
Stock-settled compensation expense	$ 5.4	$ 4.2
Cash-settled RSUs	1.0	2.1
Total compensation expense	6.4	6.3
Income tax benefit	(1.5)	(1.5)
Total compensation expense, net of tax benefit	4.9	4.8
Stock-settled restricted stock units
Compensation expense
Stock-settled compensation expense	2.8	2.1
Performance shares
Compensation expense
Stock-settled compensation expense	2.5	2.0
Stock options
Compensation expense
Stock-settled compensation expense	$ 0.1	$ 0.1

Allocated Share-based Compensation Expense, Cash-settled Restricted Stock Units

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Allocated Share-based Compensation Expense, Stock-settled Compensation Expense

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Amount, after tax, of expense for award under share-based payment arrangement.

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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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