Stock-Based Compensation - Non-Cash Stock-Based Compensation Expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total non-cash stock compensation expense	$ 1,494	$ 935
Selling and Marketing [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total non-cash stock compensation expense	247	112
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total non-cash stock compensation expense	278	207
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total non-cash stock compensation expense	$ 969	$ 616