Medical Claims Liability - Narrative (Details) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022
Insurance [Abstract]
Amounts recorded as an adjustment to premium revenues related to minimum HBR and return of premium programs	$ 341	$ 121
Short-duration insurance contracts, Incurred but not reported and expected development on reported claims	$ 11,661

Undiscounted amount, after reinsurance, of incurred-but-not-reported (IBNR) liabilities plus expected development on reported claims, for claims and allocated claim adjustment expense for short-duration insurance contracts. Excludes unallocated claim adjustment expense.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 4D
-Subparagraph (a)
-SubTopic 40
-Topic 944
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480081/944-40-50-4D

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 4E
-SubTopic 40
-Topic 944
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480081/944-40-50-4E

Name:	us-gaap_ShortdurationInsuranceContractsIncurredButNotReportedIbnrClaimsLiabilityNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant