Restructuring and Other Expense - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 28, 2018	Feb. 28, 2017	Feb. 28, 2018	Feb. 28, 2017
Restructuring Cost and Reserve [Line Items]
Net gain (loss) on sale of assets	$ 1,437	$ (1,875)	$ 10,692	$ (3,358)
AMTROL
Restructuring Cost and Reserve [Line Items]
Severance expense			2,365
Other Non-significant Restructuring Activities
Restructuring Cost and Reserve [Line Items]
Severance expense			195
Net gain (loss) on sale of assets			(143)
Facility exit costs credit			(78)
Closure of Precision Specialty Metals, Inc
Restructuring Cost and Reserve [Line Items]
Facility exit costs			577
Net gain (loss) on sale of assets			10,595
Cash proceeds from sale of business			$ 15,874