Description of the Business and Basis of Presentation - Deferred Revenue Balances (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Deferred Revenue Disclosure [Abstract]
Deferred revenue, including long-term portion	$ 140,741	$ 114,416
Less: Deferred revenue, long-term portion, included in other liabilities	11,577	10,000
Deferred revenue, short-term portion	$ 129,164	$ 104,416