SCHEDULE II - Valuation and Qualifying Accounts (Detail) - Allowance for Doubtful Accounts - USD ($) $ in Thousands		12 Months Ended
		May 31, 2019	May 31, 2018	May 31, 2017
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period		$ 632	$ 3,444	$ 4,579
Charged to Costs and Expenses		659	11	269
Uncollectable Accounts Charged to Allowance	[1]	(141)	(2,823)	(1,404)
Balance at End of Period		$ 1,150	$ 632	$ 3,444

[1] For fiscal 2018, the balance also includes $1,215,000 related to Worthington Aritas that was reclassified to assets held for sale.