Information about Geographic Areas - Additional Information (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) sales_force Segment	Sep. 30, 2018 USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of sales forces | sales_force			1
Number of reportable segment | Segment			1
Total revenue	$ 30,604	$ 28,616	$ 88,637	$ 76,700
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 21,300	$ 20,400	$ 61,700	$ 51,200