Restructuring and Other Expense - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Nov. 30, 2016	Nov. 30, 2015	Nov. 30, 2016	Nov. 30, 2015
Restructuring Cost and Reserve [Line Items]
Net gain (loss) on sale of assets	$ 2,912,000	$ 5,854,000	$ (1,484,000)	$ 4,248,000
Cryogenics Facility in Istanbul, Turkey, to its Greenfield Facility in Bandirma, Turkey
Restructuring Cost and Reserve [Line Items]
Severance expense			309,000
Facility exit costs			421,000
Closure of Precision Specialty Metals, Inc
Restructuring Cost and Reserve [Line Items]
Facility exit costs			1,264,000
Other Non-significant Restructuring Activities
Restructuring Cost and Reserve [Line Items]
Severance expense			93,000
Facility exit costs			27,000
Net gain (loss) on sale of assets			(86,000)
Pressure Cylinders
Restructuring Cost and Reserve [Line Items]
Severance expense			1,356,000
Engineered Cabs | Facility Closing | Florence, South Carolina
Restructuring Cost and Reserve [Line Items]
Facility exit costs			307,000
Net gain (loss) on sale of assets			(101,000)
Engineered Cabs | Advanced Component Technologies, Inc
Restructuring Cost and Reserve [Line Items]
Cash proceeds from sale of business			700,000
Gain (loss) on sale of business			$ (822,000)