Description of Business and Summary of Significant Accounting Policies - Cash and cash equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Description of Business and Summary of Significant Accounting Policies
Restricted cash equivalents	$ 300
Cash and cash equivalents	315,741	$ 196,046
Restricted cash - current	8,551	11,407
Restricted cash, non-current	500
Cash, cash equivalents and restricted cash	$ 324,792	$ 207,453	$ 7,179	$ 7,236