Impairment of Goodwill and Long-Lived Assets - Additional Information (Detail) - USD ($)	3 Months Ended				6 Months Ended
	Nov. 30, 2018	Aug. 31, 2018	May 31, 2018	Nov. 30, 2017	Nov. 30, 2018	Nov. 30, 2017
Impaired Long Lived Assets Held And Used [Line Items]
Impairment of long-lived assets				$ 8,289,000	$ 2,381,000	$ 8,289,000
Pressure Cylinders
Impaired Long Lived Assets Held And Used [Line Items]
Impairment of long-lived assets				$ 964,000	2,381,000	$ 964,000
Carrying value long-lived assets	$ 34,000,000
Worthington Aritas
Impaired Long Lived Assets Held And Used [Line Items]
Impairment of long-lived assets		$ 2,381,000	$ 42,422,000
Fair Value, Measurements, Nonrecurring
Impaired Long Lived Assets Held And Used [Line Items]
Fair market value of assets	$ 0		30,000,000		$ 0
Fair Value, Measurements, Nonrecurring | Significant Other Observable Inputs (Level 2)
Impaired Long Lived Assets Held And Used [Line Items]
Fair market value of assets			30,000,000
Fair Value, Measurements, Nonrecurring | Worthington Aritas
Impaired Long Lived Assets Held And Used [Line Items]
Fair market value of assets		7,000,000	$ 9,000,000
Fair Value, Measurements, Nonrecurring | Worthington Aritas | Significant Other Observable Inputs (Level 2)
Impaired Long Lived Assets Held And Used [Line Items]
Fair market value of assets		$ 7,000,000