Revenues from Contracts with Customers - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Deferred revenue	$ 1.9		$ 4.2
Deferred revenue, revenue recognized	$ 2.3	$ 1.2