Components of Inventories (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current inventory:
Raw materials	$ 34,267	$ 35,314
Work in process	8,687	8,131
Finished goods	11,989	9,054
Total current inventory	54,943	52,499
Long term inventory	13,202	6,316
Total inventory	$ 68,145	$ 58,815