Restricted Cash and Investments - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022	Jun. 30, 2022	Dec. 31, 2021
Restricted Investments Note [Abstract]
Cash and cash equivalents	$ 459,368	$ 595,381	$ 476,792
Bond purchase fund	0		30,975
Restricted cash included in restricted cash and short-term investments	5,600		84,600
Total cash, cash equivalents and restricted cash reported in the consolidated statements of cash flows	$ 464,968	$ 625,781	$ 592,367	$ 581,150