Description of Business and Summary of Significant Accounting Policies - Cash, Cash Equivalents, and Restricted Cash Shown in the Statement of Cash Flows (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Cash and cash equivalents	$ 87,671	$ 105,035	$ 88,023
Restricted cash	8,817	8,519	7,902
Restricted cash included in other long-term assets	7,362		6,073
Total cash, cash equivalents, and restricted cash shown in the Condensed Consolidated Statement of Cash Flows	$ 103,850	$ 120,213	$ 101,998	$ 111,369