Fair Value - Assets Measured at Fair Value on Non-Recurring Basis (Detail) - Fair Value, Nonrecurring - USD ($) $ in Thousands	Feb. 28, 2022		May 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis	$ 700		$ 400
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis	700		400
Long Lived Assets Held for Sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis	700	[1]	400	[2]
Long Lived Assets Held for Sale | Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis	$ 700	[1]	$ 400	[2]

[1] Comprised of production equipment at our Twinsburg, Ohio facility with an estimated fair market value of $700,000.  Refer to “NOTE F – Goodwill and Long-Lived Assets” for additional information.

[2] Comprised of our alternative fuel cylinders assets at the Jefferson, Ohio facility with an estimated fair market value of $400,000.  Refer to “NOTE F – Goodwill and Long-Lived Assets” for additional information.