Revenue - Summary of Changes in Deferred Revenue Related to Material Right Performance Obligations (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue From Contract With Customer [Abstract]
Balance, beginning of period	$ 80,887	$ 70,004	$ 76,244	$ 64,651
Deferral of revenue	7,838	6,631	20,324	17,651
Recognition of unearned revenue	(3,338)	(3,270)	(11,181)	(8,937)
Balance, end of period	$ 85,387	$ 73,365	$ 85,387	$ 73,365