Supplementary Information - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Supplementary Information [Abstract]
Cash and cash equivalents	$ 455,858	$ 241,221
Restricted cash included in other long-term assets	156	326
Total cash, cash equivalents, and restricted cash	$ 456,014	$ 241,547	$ 245,679	$ 223,497