Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 50,906		$ 33,498
Work-in-process	26,649		22,040
Finished products	3,522		1,813
Total inventories	81,077		57,351
Less reserves	(3,105)		(3,204)
Total inventories, net	$ 77,972	$ 51,326	$ 54,147