GOODWILL AND OTHER INTANGIBLE ASSETS - Details of Intangible Assets Included in Other Long-Term Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Intangible Assets
Weighted Average Life	8 years 8 months 12 days
Cost	$ 829	$ 827
Accumulated Amortization	652	582
Net	$ 177	245
Customer contracts/relationships
Intangible Assets
Weighted Average Life	8 years 8 months 12 days
Cost	$ 646	646
Accumulated Amortization	496	434
Net	$ 150	212
Trade names and technology
Intangible Assets
Weighted Average Life	6 years 4 months 24 days
Cost	$ 84	84
Accumulated Amortization	84	83
Net	$ 0	1
Provider contracts
Intangible Assets
Weighted Average Life	11 years 9 months 18 days
Cost	$ 70	68
Accumulated Amortization	44	37
Net	$ 26	31
Noncompetes and other
Intangible Assets
Weighted Average Life	7 years 3 months 18 days
Cost	$ 29	29
Accumulated Amortization	28	28
Net	$ 1	$ 1