Accrued Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Accrued compensation and related costs	$ 5,613	$ 7,372
Accrued professional services	3,006	2,605
Accrued customer obligations	696	481
Accrued insurance premiums	254	507
Other accrued expenses	788	747
Total accrued liabilities	$ 10,357	$ 11,712