Summary of Significant Accounting Policies - Company's Condensed Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2022	Mar. 31, 2022	Jan. 01, 2022	Dec. 31, 2021
Accounting Policies [Line Items]
Premium deficiency reserve	$ 291		$ 7,239				$ 109,905
Total current liabilities	907,758		431,507				371,901
Total liabilities	927,427		451,733				410,764
Accumulated deficit	(2,047,853)		(1,946,433)			$ 1,616,000	(1,616,015)
Total stockholders' equity	330,570	$ 323,107	356,887	$ 427,283	$ 490,355		540,040
Total liabilities and stockholders' equity	1,257,997		808,620				950,804
Previously reported
Accounting Policies [Line Items]
Premium deficiency reserve	2,681		16,388				110,628
Total current liabilities	910,148		440,656				372,624
Total liabilities	929,817		460,882				411,487
Accumulated deficit	(2,050,243)		(1,955,582)				(1,616,738)
Total stockholders' equity	328,180		347,738				539,317
Total liabilities and stockholders' equity	1,257,997		808,620				950,804
Effect of Change
Accounting Policies [Line Items]
Premium deficiency reserve	(2,390)		(9,149)				(723)
Total current liabilities	(2,390)		(9,149)				(723)
Total liabilities	(2,390)		(9,149)				(723)
Accumulated deficit	2,390		9,149				723
Total stockholders' equity	2,390		9,149				723
Total liabilities and stockholders' equity	$ 0		$ 0				$ 0