Restructuring and Other Expense - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Feb. 28, 2015	May 31, 2017	May 31, 2016	May 31, 2015
Restructuring Cost and Reserve [Line Items]
Net gain (loss) on sale of assets		$ (7,951)	$ 12,996	$ (3,277)
Cryogenics Facility in Istanbul, Turkey, to its Greenfield Facility in Bandirma, Turkey
Restructuring Cost and Reserve [Line Items]
Severance expense		699
Facility exit costs		1,299
Closure of Precision Specialty Metals, Inc
Restructuring Cost and Reserve [Line Items]
Facility exit costs		1,999
Severance expense credit		(106)
Other Non-significant Restructuring Activities
Restructuring Cost and Reserve [Line Items]
Severance expense credit		(95)
Net gain (loss) on sale of assets		(87)
Facility exit costs credit		(50)
Pressure Cylinders
Restructuring Cost and Reserve [Line Items]
Severance expense		1,356
Engineered Cabs
Restructuring Cost and Reserve [Line Items]
Loss on sale of business	$ 332
Engineered Cabs | Facility Closing | Florence, South Carolina
Restructuring Cost and Reserve [Line Items]
Facility exit costs		504
Net gain (loss) on sale of assets		104
Engineered Cabs | Advanced Component Technologies, Inc
Restructuring Cost and Reserve [Line Items]
Cash proceeds from sale of business		700
Loss on sale of business		$ (822)