Description of the Business and Basis of Presentation - Deferred Revenue Balances (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Deferred Revenue Disclosure [Abstract]
Deferred revenue, including long-term portion	$ 188,441	$ 144,187
Less: Deferred revenue, long-term portion, included in other liabilities	15,010	13,428
Deferred revenue, short-term portion	$ 173,431	$ 130,759