FAIR VALUE - Narrative (Details) - USD ($)	9 Months Ended
	Sep. 30, 2021	Apr. 27, 2021	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Termination of put and call options	$ 377,000,000
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes debt outstanding	9,000,000,000			$ 6,100,000,000
Term loans and commercial paper borrowings	3,200,000,000
Commercial paper borrowings				600,000,000
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Senior notes debt outstanding	$ 10,100,000,000			7,400,000,000
Kindred at Home
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity interest to be acquired per agreement (percent)		60.00%
Put option | Other long-term liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial liability		$ 0	$ 63,000,000	45,000,000
Call option | Other long-term assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair value of financial asset		$ 0	$ 440,000,000	$ 503,000,000