Reconciliation of Cash and Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Cash and cash equivalents presented in the consolidated condensed balance sheets	$ 226,533	$ 50,443
Restricted cash	2,506	2,505
Cash, cash equivalents and restricted cash presented in the consolidated condensed statements of cash flows	$ 229,039	$ 52,948	$ 47,704	$ 39,620