Inventories - Inventories, Net of Reserves (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Raw materials	$ 64,579	$ 60,098
In-process and finished	124,459	115,874
Supplies	73,853	71,242
Total	$ 262,891	$ 247,214