Inventories, net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Mar. 31, 2016	Sep. 30, 2015	Jun. 30, 2015
Inventories, net additional information
Inventory reserves	$ 600	$ 800		$ 200	$ 300	$ 300
Charges to cost of sales due to below normal production capacity			$ 1,000
Charges to cost of sales due to lower of cost or market value	800	500	800
Inventory reserves
Inventories, net additional information
Decrease in inventory reserves	2,619	14,362	2,452
Reduction in inventory reserves	1,600
Provision charge to reserve	1,051	1,185	$ 1,003
Inventory reserves	$ 8,800	$ 10,500