Fair Value Measurements - Assets Measured at Fair Value on Non-Recurring Basis (Parenthetical) (Detail) - USD ($)			3 Months Ended										12 Months Ended
		Nov. 01, 2019	Nov. 30, 2020	[1]	Aug. 31, 2020		May 31, 2020		Feb. 29, 2020		Aug. 31, 2019		May 31, 2021	May 31, 2020	May 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill and long-lived assets			$ 3,815,000		$ 9,924,000	[1]	$ 7,462,000	[1]	$ 34,627,000	[1]	$ 40,601,000	[1]	$ 13,739,000	$ 82,690,000	$ 7,817,000
Impairment of ROU assets							565,000				4,843,000
Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair market value of assets							26,984,000						400,000	26,984,000
Fair Value, Nonrecurring | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair market value of assets							16,423,000							16,423,000
Oil & gas equipment | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
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							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
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
Noncontrolling Interests | Engineered Cabs
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 cabs		$ 13,623,000
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, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair market value of assets									700,000
Long Lived Assets Held And Used
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair market value of assets							2,800,000							2,800,000
Long Lived Assets Held And Used | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair market value of assets	[2],[3],[4],[5],[6],[7]						9,277,000							9,277,000
Long Lived Assets Held And Used | Fair Value, Nonrecurring | Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair market value of assets	[2],[3],[4],[5],[6],[7]						2,800,000							2,800,000
Long Lived Assets Held And Used | Engineered Cabs | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair market value of assets					$ 12,860,000
Long Lived Assets Held And Used | Packing Solutions Business
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [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 | Alternative Fuel Cylinders Manufacturing Line Facility | Jefferson
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair market value of assets													$ 400,000
Fixed Assets [Member] | Oil And Gas Operations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair market value of assets									6,211,000
Goodwill | Oil And Gas Operations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill and long-lived assets									$ 22,097,000

[1] For additional information regarding the Company’s impairment activity, refer to “Note E – 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 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.