Fair Value Measurements - Assets Measured at Fair Value on Non-Recurring Basis (Parenthetical) (Detail) - USD ($)	3 Months Ended				12 Months Ended
	May 31, 2018		Nov. 30, 2017	[1]	May 31, 2018	May 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill and long-lived assets	$ 52,919,000	[1]	$ 8,289,000		$ 61,208,000	$ 25,962,000
Oil And Gas Equipment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill and long-lived assets	10,497,000
Worthington Aritas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill and long-lived assets	42,422,000
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis	30,000,000				30,000,000
Fair Value, Measurements, Nonrecurring | Oil And Gas Equipment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis	21,000,000				21,000,000
Fair Value, Measurements, Nonrecurring | Worthington Aritas
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis	$ 9,000,000				$ 9,000,000

[1] For additional information regarding the Company’s impairment activity, refer to “Note C – Goodwill and Other Long-Lived Assets.”