Revenue from Contracts with Customers - Deferred Revenue (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Deferred revenue
As of January 1, 2018 (adjusted)	$ 21,459	$ 24,708
Net additions		100,271
Revenue recognized	$ (130,000)	(103,520)
As of December 31, 2018		$ 21,459