Organization and Basis of Presentation - Cash, Cash Equivalents and Restricted Cash And Cash Equivalents (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents-unrestricted	$ 49,910	$ 73,629	$ 558,446	$ 70,087
Cash and cash equivalents-restricted	11,042	10,412	10,629	11,007
Total unrestricted and restricted cash and cash equivalents shown in the condensed consolidated statement of cash flows	$ 60,952	$ 84,041	$ 569,075	$ 81,094