Basis of Presentation, Summary of Significant Accounting Policies and Change in Accounting Principles - Restricted Cash and Restricted Investments (Details) - USD ($) $ in Thousands		Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted funds			$ 88,662
Current restricted cash		$ 39,647	75,685
Total current restricted cash and restricted investments		39,647	75,685
Non-current restricted cash		12,981	12,977
Total non-current restricted cash and restricted investments		12,981	12,977
Cash and cash equivalents		210,158		$ 236,032
Restricted cash and restricted investments		52,628		67,737
Restricted investments included in restricted cash and restricted investments		0		0
Total cash and cash equivalents and restricted cash shown in the consolidated statements of cash flows	[1]	262,786	354,942	$ 303,769	$ 361,564
Collateral for letters of credit for facility leases
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted funds		2,269	3,769
Collateral with financial institutions
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted funds		11,499	11,662
Claims processing services
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted funds		38,855	73,226
Other
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted funds		5	5
Bank time deposits
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted funds		$ 11,500	$ 11,700

[1] As a result of the closing of the sale of True Health during the first quarter of 2021, the consolidated statement of operations and related financial information reflect the Company’s operations and assets and liabilities of True Health as discontinued operations. Cash flows and comprehensive income have not been adjusted and are included in the consolidated statements of cash flows and consolidated statements of comprehensive income (loss) for the three months ended March 31, 2021. See Note 5.