Inventories (Tables)

12 Months Ended

Dec. 31, 2017

Inventory Disclosure [Abstract]

Schedule of Inventories

	2017		2016
Raw materials	$	24,249	$	23,964
Work-in-progress		42,840		29,198
Finished goods		24,083		20,046
Supplies		16,389		10,371
Inventories	$	107,561	$	83,579