Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Inventories
Raw materials and supplies	$ 38,132	$ 31,878
Work in process	19,938	21,455
Finished goods	26,396	19,867
Total inventory	84,466	73,200
Less reserve for excess and obsolete inventories	(2,224)	(2,535)
Total inventory, net	$ 82,242	$ 70,665