Description of the Business and Basis of Presentation - Summary of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 553,570	$ 433,909
Restricted cash, included in prepaid expenses and other current assets	$ 1,588	$ 1,316
Restricted cash, current, asset, statement of financial position [extensible list]	us-gaap:OtherAssetsCurrent	us-gaap:OtherAssetsCurrent
Total cash, cash equivalents and restricted cash	$ 555,158	$ 435,225	$ 489,871	$ 40,925