HEALTH CARE REFORM (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Premium Deficiency Reserve Activity [Roll Forward]
Balance at January 1, 2016	$ 206	$ 206		$ 206
Current period results applied to the PDR liability for the 2016 coverage year				(178)
Change in full year 2016 estimate recorded in benefits expense				208
Balance at September 30, 2016				176
Other current assets	4,791	4,791		4,791		$ 4,712
Trade accounts payable and accrued expenses	(2,933)	(2,933)		(2,933)		(2,212)
Other long-term assets	2,789	2,789		2,789		2,475
Other long-term liabilities	(279)	(279)		(279)		(235)
Risk Adjustment Settlement
Premium Deficiency Reserve Activity [Roll Forward]
Total net (liability) asset	144	144		144		(87)
Reinsurance Recoverables
Premium Deficiency Reserve Activity [Roll Forward]
Total net (liability) asset	215	215		215		610
Risk Corridor Settlement
Premium Deficiency Reserve Activity [Roll Forward]
Total net (liability) asset	591	591		591		459
Health Care Reform
Premium Deficiency Reserve Activity [Roll Forward]
Payment of annual health insurance industry fee	916
Amortization of deferred charges		231	$ 217	687	$ 650
Deferred cost asset balance	229	229		229
2016 Coverage Year
Premium Deficiency Reserve Activity [Roll Forward]
Balance at September 30, 2016				176
2016 Coverage Year | Risk Adjustment Settlement
Premium Deficiency Reserve Activity [Roll Forward]
Trade accounts payable and accrued expenses	(107)	(107)		(107)		0
Other long-term assets	197	197		197		0
Total net (liability) asset	90	90		90		0
2016 Coverage Year | Reinsurance Recoverables
Premium Deficiency Reserve Activity [Roll Forward]
Trade accounts payable and accrued expenses	0	0		0		0
Other long-term assets	157	157		157		0
Total net (liability) asset	157	157		157		0
2016 Coverage Year | Risk Corridor Settlement
Premium Deficiency Reserve Activity [Roll Forward]
Trade accounts payable and accrued expenses	0	0		0		0
Other long-term assets	168	168		168		0
Total net (liability) asset	168	168		168		0
Current Coverage Year
Premium Deficiency Reserve Activity [Roll Forward]
Payments for risk adjustment charges				240	186
Proceeds from reinsurance recoverable				471	521
Proceeds from risk adjustment settlements				84	$ 57
Current Coverage Year | Risk Adjustment Settlement
Premium Deficiency Reserve Activity [Roll Forward]
Premiums receivable	54	54		54		126
Other current assets	0	0		0		0
Trade accounts payable and accrued expenses	0	0		0		(223)
Net current asset (liability)	54	54		54		(97)
Other long-term assets	0	0		0		10
Total net (liability) asset	54	54		54		(87)
Current Coverage Year | Reinsurance Recoverables
Premium Deficiency Reserve Activity [Roll Forward]
Premiums receivable	0	0		0		0
Other current assets	58	58		58		610
Trade accounts payable and accrued expenses	0	0		0		0
Net current asset (liability)	58	58		58		610
Other long-term assets	0	0		0		0
Total net (liability) asset	58	58		58		610
Current Coverage Year | Risk Corridor Settlement
Premium Deficiency Reserve Activity [Roll Forward]
Premiums receivable	0	0		0		0
Other current assets	0	0		0		0
Trade accounts payable and accrued expenses	0	0		0		0
Net current asset (liability)	0	0		0		0
Other long-term assets	423	423		423		459
Total net (liability) asset	$ 423	$ 423		423		$ 459
2014 Coverage Year | Risk Corridor Settlement
Premium Deficiency Reserve Activity [Roll Forward]
Proceeds from risk corridor settlements				$ 30
Percent of receivable to be paid by CMS (between December 2015 and January 2016)	12.60%	12.60%		12.60%