GOODWILL AND OTHER INTANGIBLE ASSETS - Details of Intangible Assets Included in Other Long-Term Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Intangible Assets
Weighted Average Life	9 years 3 months 18 days
Cost	$ 1,069	$ 829
Accumulated Amortization	740	652
Net	$ 329	177
Customer contracts/relationships
Intangible Assets
Weighted Average Life	9 years 6 months
Cost	$ 849	646
Accumulated Amortization	572	496
Net	$ 277	150
Trade names and technology
Intangible Assets
Weighted Average Life	7 years
Cost	$ 122	84
Accumulated Amortization	89	84
Net	$ 33	0
Provider contracts
Intangible Assets
Weighted Average Life	11 years 9 months 18 days
Cost	$ 69	70
Accumulated Amortization	50	44
Net	$ 19	26
Noncompetes and other
Intangible Assets
Weighted Average Life	7 years 3 months 18 days
Cost	$ 29	29
Accumulated Amortization	29	28
Net	$ 0	$ 1