Fair Value Measurements - Assets Measured at Fair Value on Non-Recurring Basis (Parenthetical) (Detail) - USD ($)		3 Months Ended												12 Months Ended
	Nov. 01, 2019	Aug. 31, 2020	May 31, 2020		Feb. 29, 2020		Aug. 31, 2019		May 31, 2019		Aug. 31, 2018		May 31, 2018	May 31, 2020		May 31, 2019		May 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis			$ 2,800,000											$ 2,800,000
Impairment of goodwill and long-lived assets			7,462,000	[1]	$ 34,627,000	[1]	$ 40,601,000	[1]	$ 5,436,000	[1]	$ 2,381,000	[1]		82,690,000		$ 7,817,000		$ 61,208,000
Impairment of ROU assets			565,000				$ 4,843,000
Fair market value of assets			2,800,000											2,800,000
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			26,984,000						11,938,000					26,984,000		11,938,000
Fair market value of assets			26,984,000						11,938,000					26,984,000		11,938,000
Fair Value, Measurements, Nonrecurring | CNG Fuel Systems
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis									238,000							238,000
Impairment of goodwill and long-lived assets									2,167,000
Fair market value of assets									238,000							238,000
Fair Value, Measurements, Nonrecurring | Long Lived Assets Held And Used
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis			9,277,000	[2],[3],[4],[5],[6],[7]					7,000,000	[8]				9,277,000	[2],[3],[4],[5],[6],[7]	7,000,000	[8]
Fair market value of assets			9,277,000	[2],[3],[4],[5],[6],[7]					7,000,000	[8]				9,277,000	[2],[3],[4],[5],[6],[7]	7,000,000	[8]
Nisshin Joint Venture | Noncontrolling Interests
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					1,274,000
WSP Joint Venture | 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					700,000
Fair market value of assets					700,000
Nisshin
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis									3,700,000							3,700,000
Impairment of goodwill and long-lived assets							$ 4,236,000		4,017,000
Fair market value of assets									3,700,000							3,700,000
Nisshin | 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									3,700,000							3,700,000
Fair market value of assets									$ 3,700,000							$ 3,700,000
Nisshin | Noncontrolling Interests
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, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill and long-lived assets											2,381,000		$ 42,422,000
Worthington Aritas | 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							7,000,000				7,000,000		9,000,000					9,000,000
Impairment of goodwill and long-lived assets							2,381,000
Fair market value of assets							7,000,000				$ 7,000,000		$ 9,000,000					$ 9,000,000
Worthington Specialty Processing | 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									$ 1,000,000							$ 1,000,000
Impairment of goodwill and long-lived assets									3,269,000
Fair market value of assets									$ 1,000,000							$ 1,000,000
Engineered Cabs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of ROU assets		$ 905,000
Engineered Cabs | Fair Value, Measurements, Nonrecurring | Long Lived Assets Held And Used
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis		12,860,000
Fair market value of assets		$ 12,860,000
Engineered Cabs | Noncontrolling Interests
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	$ 13,623,000
Oil And Gas Operations | Fixed Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis					6,211,000
Fair market value of assets					6,211,000
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					22,097,000,000
Oil And Gas Operations | 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					3,384,000
Fair market value of assets					$ 3,384,000
TWB Hermosillo
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of ROU assets			565,000
Packing Solutions Business
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill and long-lived assets														2,544,000
Packing Solutions Business | Long Lived Assets Held And Used
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis			266,000											266,000
Carrying value long-lived assets			2,810,000											2,810,000
Fair market value of assets			266,000											266,000
Packing Solutions Business | Fair Value, Measurements, Nonrecurring | Long Lived Assets Held And Used
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset measured at fair value on non-recurring basis			266,000											266,000
Carrying value long-lived assets			2,810,000											2,810,000
Fair market value of assets			$ 266,000											$ 266,000
Engineered Cabs Operating Segment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill and long-lived assets							1,469,000
Impairment of ROU assets							$ 3,938,000

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

[2] During the fourth quarter of fiscal 2020, the Company identified an impairment indicator related to the TWB Hermosillo facility operating lease due to the economic impact of COVID-19.  As a result, the lease ROU asset with a net book value of $565,000 was deemed fully impaired and written off.

[3] During the third quarter of fiscal 2020, the Company identified an impairment indicator for our oil & gas equipment business and performed an interim impairment test of the reporting unit.  In accordance with the applicable accounting guidance, the book value of the corresponding goodwill was written off, resulting in an impairment charge of $22,097,000.

[4] In May 2020, the Company committed to a plan to shut down the packaging solutions business in Greensburg, Indiana.  As a result, long-lived assets with a carrying value of $2,810,000 were written down to their estimated fair market value of $266,000.

[5] During the fourth quarter of 2020, in connection with the annual indefinite lived assets impairment test, certain European tradenames were written down to their estimated fair market value of $2,800,000.

[6] During the first quarter of fiscal 2020, the Company identified an impairment indicator for the fabricated products business in Stow, Ohio within the former Engineered Cabs operating segment.  As a result, fixed assets with a net book value of $1,469,000 and lease ROU assets with a net book value of $3,938,000 were deemed to be fully impaired and written off.

[7] During the third quarter of fiscal 2020, in connection with the closure of the oil & gas equipment manufacturing operations in Wooster, Ohio, customer list intangible assets were determined to be fully impaired and written off.  In addition, the remaining fixed assets at Wooster, Ohio were written down to their estimated fair market value of $6,211,000.

[8] During the fourth quarter of fiscal 2019, in connection with the closure of the CNG fuel systems facility in Salt Lake City, Utah, long-lived assets consisting primarily of technology-related intangible assets and fixed assets were written down to their estimated fair value of $238,000, resulting in an impairment charge of $2,167,000.  During the fourth quarter of fiscal 2019, certain long-lived assets at our consolidated joint venture, WSP, were written down to their estimated fair market value of $1,000,000, resulting in an impairment charge of $3,269,000