Revenue Recognition - Summary of Contract Assets Offset with Deferred Revenue Balances (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Revenue Recognition [Abstract]
Gross deferred revenue	$ 55,056	$ 67,817	$ 63,204	$ 35,611	$ 45,801	$ 51,694
Gross contract assets	(25,753)		(38,557)
Deferred revenue, net	$ 29,303		$ 24,647