Other Long-term Liabilities - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other Liabilities Disclosure [Line Items]
Asset retirement obligations		$ 397	$ 1,018
Expenditures	$ 397	$ 642
ARO reserve reclassified to other long-term liabilities	200
Facility Lease [Member]
Other Liabilities Disclosure [Line Items]
Expenditures	$ 200