Goodwill and Other Long-Lived Assets - Additional Information (Detail)		3 Months Ended								12 Months Ended
		May 31, 2018 USD ($)		Nov. 30, 2017 USD ($)		May 31, 2016 USD ($) asset_group	Nov. 30, 2015 USD ($) Facility	Aug. 31, 2015 USD ($)	May 31, 2015 asset_group	May 31, 2018 USD ($)	May 31, 2017 USD ($)	May 31, 2016 USD ($)
Goodwill And Other Intangible Assets [Line Items]
Impairment losses										$ 9,666,000
Impairment of goodwill and long-lived assets		$ 52,919,000	[1]	$ 8,289,000	[1]					61,208,000		$ 25,962,000
Amortization expense										19,679,000	$ 13,525,000	15,813,000
Number of asset group tested for impairment | asset_group						5			5
Goodwill		345,183,000				$ 246,067,000				345,183,000	247,673,000	246,067,000
Pressure Cylinders
Goodwill And Other Intangible Assets [Line Items]
Impairment losses										4,015,000
Impairment of goodwill and long-lived assets										53,883,000		22,962,000
Goodwill		337,284,000				$ 233,371,000				337,284,000	$ 234,123,000	233,371,000
Engineered Cabs
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets								$ 3,000,000				$ 3,000,000
Engineered Cabs | Long-lived Assets Held and Used
Goodwill And Other Intangible Assets [Line Items]
Carrying value long-lived assets								4,059,000
Fair Value, Measurements, Nonrecurring
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets		30,000,000								30,000,000
Fair Value, Measurements, Nonrecurring | Long-lived Assets Held and Used
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets	[2]	30,000,000								30,000,000
Fair Value, Measurements, Nonrecurring | Engineered Cabs | Long-lived Assets Held and Used
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets								$ 1,059,000
Oil And Gas Equipment
Goodwill And Other Intangible Assets [Line Items]
Impairment losses		4,015,000
Impairment of goodwill and long-lived assets		10,497,000
Impairment of fixed assets		2,633,000
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
Worthington Aritas
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets		42,422,000
Impairment of fixed assets		19,621,000
Impairment of intangible assets		11,549,000
Impairment of other assets		11,252,000
Worthington Aritas | Fair Value, Measurements, Nonrecurring
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets		$ 9,000,000								9,000,000
WEI
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets										$ 1,674,000
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
Oil and Gas Equipment
Goodwill And Other Intangible Assets [Line Items]
Impairment losses										$ 4,015,000
Oil and Gas Equipment | Pressure Cylinders
Goodwill And Other Intangible Assets [Line Items]
Impairment of goodwill and long-lived assets							$ 22,962,000
Number of equipment facilities | Facility							2
Carrying value long-lived assets							$ 59,895,000
Cash flow projections, discount rate							13.00%
Goodwill							$ 25,982,000
Oil and Gas Equipment | Fair Value, Measurements, Nonrecurring | Pressure Cylinders | Long-lived Assets Held and Used
Goodwill And Other Intangible Assets [Line Items]
Fair market value of assets							$ 36,933,000
WEI Reporting Unit
Goodwill And Other Intangible Assets [Line Items]
Impairment losses										$ 5,651,000
Sale of stake, percentage										65.00%
Impairment of goodwill and long-lived assets				$ 7,325,000

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

[2] During the fourth quarter of fiscal 2018, management committed to a plan to sell the Company’s cryogenics business in Turkey, Worthington Aritas, and certain underperforming oil & gas equipment assets within Pressure Cylinders. In accordance with the applicable accounting guidance, the net assets were recorded at the lower of net book value or fair value less costs to sell. The book value of Worthington Aritas exceeded its estimated fair market value of $9,000,000, resulting in an impairment charge of $42,422,000. The book value of the oil & gas equipment asset group also exceeded its estimated fair market value of $21,000,000, resulting in an impairment charge of $10,497,000.