Inventories (Tables)

6 Months Ended

Jun. 30, 2018

Inventory Disclosure [Abstract]

Schedule of Inventories

Inventories were comprised of the following:

	June 30, 2018		December 31, 2017
Raw materials	$	22,717	$	24,249
Work-in-process		46,692		42,840
Finished goods		24,516		24,083
Supplies		18,031		16,389
Inventories	$	111,956	$	107,561