SEGMENT INFORMATION - Narrative (Details) $ in Millions	1 Months Ended	3 Months Ended	9 Months Ended
Dec. 31, 2022 segment	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) segment	Sep. 30, 2022 USD ($)
Segment Reporting [Abstract]
Number of reportable segments \| segment	2			2
Member co-share amounts and government subsidies		$ 5,700	$ 5,400	$ 14,700	$ 14,200
Depreciation and amortization classified as benefit expense		$ 35	$ 30	$ 102	$ 89

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-18

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Balance Type:	na
Period Type:	duration