Goodwill and Other Long-Lived Assets - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		May 31, 2019		Aug. 31, 2018		May 31, 2018		Nov. 30, 2017		May 31, 2019	May 31, 2018	May 31, 2017
Goodwill And Other Intangible Assets [Line Items]
Amortization expense										$ 15,286	$ 19,679	$ 13,525
Impairment of goodwill and long-lived assets		$ 5,436	[1]	$ 2,381	[1]	$ 52,919	[1]	$ 8,289	[1]	7,817	61,208
Impairment losses	[2]										9,666
WEI Reporting Unit
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets								7,325
Impairment losses											5,651
Oil And Gas Equipment
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets						10,497
Impairment of fixed assets						2,633
Impairment of intangible assets						3,849
Impairment losses						4,015
Land | Bremen, Ohio
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets								$ 964
Worthington Aritas
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets				2,381		42,422
Impairment of fixed assets						19,621
Impairment of intangible assets						11,549
Impairment of other assets						11,252
CNG Fuel Systems
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets		2,167
CNG Fuel Systems | Long Lived Assets Held And Used
Goodwill And Other Intangible Assets [Line Items]
Carrying value long-lived assets		2,405								2,405
Canton
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets		3,269
Canton | Long Lived Assets Held And Used
Goodwill And Other Intangible Assets [Line Items]
Carrying value long-lived assets		4,269
Fair Value, Measurements, Nonrecurring
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets		11,938				30,000				11,938	30,000
Fair Value, Measurements, Nonrecurring | Oil And Gas Equipment
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets						21,000					21,000
Fair Value, Measurements, Nonrecurring | Worthington Aritas
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets				$ 7,000		$ 9,000					$ 9,000
Fair Value, Measurements, Nonrecurring | Long Lived Assets Held And Used
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets	[3]	1,238								1,238
Fair Value, Measurements, Nonrecurring | CNG Fuel Systems | Long Lived Assets Held And Used
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets		238								238
Fair Value, Measurements, Nonrecurring | Canton | Long Lived Assets Held And Used
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets		$ 1,000								$ 1,000
Minimum
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 2018 impairment charges included $4,015,000 of goodwill allocated to oil & gas equipment assets prior to their disposal on July 31, 2018 and $5,651,000 related to the sale of a 65% stake in WEI on March 31, 2018.

[3] During the fourth quarter of fiscal 2019, in connection with the ongoing closure of the CNG fuel system 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 value of $1,000,000