Other income, net - Schedule of Other Income Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Income and Expenses [Abstract]
Interest income	$ 1,542	$ 1,563	$ 998
Foreign exchange losses	(16)	(75)	(19)
Miscellaneous expenses	(8)	(445)	(39)
Total Other income (expenses)	$ 1,518	$ 1,043	$ 940