Summary of Financial Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total before discount and debt issuance costs	$ 13,736	$ 18,300
Less: Current portion of financial liabilities	(9,829)	(8,119)
Less: Current portion of unamortized discount and debt issuance costs	(404)	(181)
Less: Long-term portion of unamortized discount and debt issuance costs	(582)	(221)
Long-term financial liabilities	2,921	9,779
Secured Term Loan
Debt Instrument [Line Items]
Total before discount and debt issuance costs	5,000	10,000
Bank Revolving Loan Facility
Debt Instrument [Line Items]
Total before discount and debt issuance costs	$ 8,736	$ 8,300