Inventories - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Lower Of Cost Or Net Realizable Value Adjustment	$ 26,337	$ 0	$ 0
Lower Of Cost Or Net Realizable Value Adjustment Gross	18,300
Airgas [Member]
Lower Of Cost Or Net Realizable Value Adjustment	35,900
Lower Of Cost Or Net Realizable Value Adjustment Gross	$ 17,600