Goodwill and Other Long-Lived Assets - Additional Information (Detail) - USD ($)		3 Months Ended													12 Months Ended
	Feb. 12, 2020	Aug. 31, 2020	May 31, 2020		Feb. 29, 2020		Aug. 31, 2019		May 31, 2019		Aug. 31, 2018		May 31, 2018	Nov. 30, 2017	May 31, 2020		May 31, 2019		May 31, 2018	Jun. 01, 2019
Goodwill And Other Intangible Assets [Line Items]
Amortization expense															$ 12,870,000		$ 15,286,000		$ 19,679,000
Fair market value of assets			$ 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
Impairment of long-lived assets					4,679,000
Fixed asset net book value	$ 14,274,000
Intangible assets with net book value	$ 6,577,000
Impairment of goodwill					22,097,000												22,097,000	[2]
Operating lease assets			31,557,000												31,557,000					$ 42,200,000
WEI Reporting Unit
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets														$ 7,325,000
Worthington Aritas
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets											2,381,000		$ 42,422,000
Impairment of long-lived assets													19,621,000
Impairment of intangible assets													11,549,000
Impairment of other assets													11,252,000
Fair Value, Measurements, Nonrecurring
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets			26,984,000						11,938,000						26,984,000		11,938,000
Fair Value, Measurements, Nonrecurring | Worthington Aritas
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets							7,000,000				$ 7,000,000		9,000,000						9,000,000
Impairment of goodwill and long-lived assets							2,381,000
Fair Value, Measurements, Nonrecurring | Fair Value Inputs Level2
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets			10,561,000						11,938,000						10,561,000		11,938,000
TWB Hermosillo
Goodwill And Other Intangible Assets [Line Items]
Impairment of ROU assets			565,000
Packing Solutions Business
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets															2,544,000
Canton
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets									3,269,000
Canton | Fair Value Inputs Level2
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets					700,000
Engineered Cabs
Goodwill And Other Intangible Assets [Line Items]
Impairment of ROU assets		$ 905,000
Impairment of long-lived assets							$ 35,194,000
Fixed asset net book value		1,469,000
Operating lease assets		3,938,000
CNG Fuel Systems
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets									2,167,000
Long Lived Assets Held And Used | Fair Value, Measurements, Nonrecurring
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets			9,277,000	[3],[4],[5],[6],[7],[8]					7,000,000	[9]					9,277,000	[3],[4],[5],[6],[7],[8]	7,000,000	[9]
Long Lived Assets Held And Used | Fair Value, Measurements, Nonrecurring | Fair Value Inputs Level2
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets			6,477,000	[3],[4],[5],[6],[7],[8]					7,000,000	[9]					6,477,000	[3],[4],[5],[6],[7],[8]	7,000,000	[9]
Long Lived Assets Held And Used | Packing Solutions Business
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets			266,000												266,000
Carrying value long-lived assets			2,810,000												2,810,000
Long Lived Assets Held And Used | Packing Solutions Business | Fair Value, Measurements, Nonrecurring
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets			266,000												266,000
Carrying value long-lived assets			2,810,000												2,810,000
Long Lived Assets Held And Used | Canton
Goodwill And Other Intangible Assets [Line Items]
Carrying value long-lived assets									4,269,000
Long Lived Assets Held And Used | Canton | Fair Value Inputs Level2
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets			7,813,000												7,813,000
Impairment of long-lived assets					$ 1,274,000
Long Lived Assets Held And Used | Canton | Fair Value, Measurements, Nonrecurring
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets									1,000,000								1,000,000
Long Lived Assets Held And Used | Engineered Cabs | Fair Value, Measurements, Nonrecurring
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets		12,860,000
Impairment of long-lived assets		$ 35,194,000
Long Lived Assets Held And Used | CNG Fuel Systems
Goodwill And Other Intangible Assets [Line Items]
Carrying value long-lived assets									2,405,000								2,405,000
Long Lived Assets Held And Used | CNG Fuel Systems | Fair Value, Measurements, Nonrecurring
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets									$ 238,000								$ 238,000
Pressure Cylinders
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets			3,800,000
Pressure Cylinders | Long Lived Assets Held And Used
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets			$ 6,600,000												$ 6,600,000
Oil And Gas Equipment
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets													10,497,000
Impairment of long-lived assets													2,633,000
Impairment of goodwill													4,015,000
Impairment of intangible assets													3,849,000
Oil And Gas Equipment | Fair Value, Measurements, Nonrecurring
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets													$ 21,000,000						$ 21,000,000
Land | Bremen, Ohio
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets														$ 964,000
Minimum [Member]
Goodwill And Other Intangible Assets [Line Items]
Definite-lived intangible assets, estimated useful lives															1 year
Maximum
Goodwill And Other Intangible Assets [Line Items]
Definite-lived intangible assets, estimated useful lives															20 years

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

[2] Fiscal 2020 impairment losses included $22,097,000 of goodwill impairment related to the oil & gas equipment reporting unit.

[3] 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.

[4] 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.

[5] 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.

[6] 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.

[7] 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.

[8] 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.

[9] 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