Other Accrued Expenses and Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Accrued Liabilities And Other Liabilities Current [Abstract]
Share-settled liability	$ 1,000
Accrued professional fees	596	$ 1,065
Income taxes payable	36	19
Other accrued expenses	1,570	936
Total	$ 3,202	$ 2,020