Inventories - Inventories, Net of Reserves (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Raw materials	$ 65,021	$ 66,359
In-process and finished	122,792	112,507
Supplies	72,931	70,803
Total	$ 260,744	$ 249,669