Fair Value - Assets Measured at Fair Value on Non-Recurring Basis (Parenthetical) (Detail) - USD ($) $ in Thousands		3 Months Ended					9 Months Ended		12 Months Ended
	Nov. 01, 2019	Aug. 31, 2020	Feb. 29, 2020	Aug. 31, 2019	May 31, 2019	Feb. 28, 2019	Feb. 29, 2020	Feb. 28, 2019	May 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill and long-lived assets			$ 34,627			$ 0	$ 75,228	$ 2,381
Impairment of ROU assets				$ 4,843
Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets estimated fair value			23,918		$ 11,938		23,918		$ 11,938
Fair Value, Nonrecurring | CNG fuel system facility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets estimated fair value					238				238
Impairment of goodwill and long-lived assets					2,167
Nisshin Joint Venture | Noncontrolling Interest | Forecast
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percent of ownership interest held in unconsolidated affiliates		10.00%
WSP Joint Venture
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill and long-lived assets							1,274
WSP Joint Venture | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets estimated fair value			700				700
Nisshin Joint Venture
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill and long-lived assets				4,236					4,017
Nisshin Joint Venture | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets estimated fair value					$ 3,700				$ 3,700
Nisshin Joint Venture | Noncontrolling Interest
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percent of ownership interest held in unconsolidated affiliates					10.00%				10.00%
Worthington Aritas | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets estimated fair value				7,000
Impairment of goodwill and long-lived assets				2,381
Worthington Specialty Processing | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets estimated fair value					$ 1,000				$ 1,000
Impairment of goodwill and long-lived assets					$ 3,269
Engineered Cabs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of ROU assets				$ 905
Engineered Cabs | Noncontrolling Interest
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Percent of ownership interest held in unconsolidated affiliates	20.00%
Fair value of previously held equity interest in Samuel	$ 13,623
Oil And Gas Operations | Fixed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets estimated fair value			6,211				6,211
Oil And Gas Operations | Goodwill
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill and long-lived assets							22,097,000
Oil And Gas Operations | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets estimated fair value			$ 3,384				$ 3,384
Engineered Cabs Operating Segment | Forecast
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill and long-lived assets		$ 1,469
Impairment of ROU assets		$ 3,938