Retirement Plan - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Compensation And Retirement Disclosure [Abstract]
Matching contributions made	$ 0.1	$ 0.1	$ 0.3	$ 0.2
Defined contribution plan name			401(k) Plan