GOODWILL AND OTHER INTANGIBLE ASSETS - Details of Intangible Assets Included in Other Long-Term Assets (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	9 years 5 months
Cost	$ 829	$ 770
Accumulated Amortization	553	544
Net	$ 276	226
Customer contracts/ relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	9 years 7 months
Cost	$ 646	566
Accumulated Amortization	414	401
Net	$ 232	165
Trade names and technology
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	6 years 6 months
Cost	$ 83	104
Accumulated Amortization	78	84
Net	$ 5	20
Provider contracts
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	11 years 11 months
Cost	$ 68	68
Accumulated Amortization	32	30
Net	$ 36	38
Noncompetes and other
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted Average Life	8 years 1 month
Cost	$ 32	32
Accumulated Amortization	29	29
Net	$ 3	$ 3