HEALTH CARE REFORM (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Premium Deficiency Reserve Activity [Roll Forward]
Balance at January 1, 2016		$ 337		$ 337
Current period results applied to the PDR liability for the 2016 coverage year				(47)
Change in full year 2016 estimate recorded in benefits expense				208
Balance at June 30, 2016				176
Other current assets		5,337		5,337		$ 4,712
Trade accounts payable and accrued expenses		(3,873)		(3,873)		(2,212)
Other long-term assets		2,731		2,731		2,475
Other long-term liabilities		(347)		(347)		(235)
Risk Adjustment Settlement
Premium Deficiency Reserve Activity [Roll Forward]
Total net (liability) asset		(44)		(44)		(87)
Reinsurance Recoverables
Premium Deficiency Reserve Activity [Roll Forward]
Total net (liability) asset		402		402		610
Risk Corridor Settlement
Premium Deficiency Reserve Activity [Roll Forward]
Total net (liability) asset		542		542		459
Health Care Reform
Premium Deficiency Reserve Activity [Roll Forward]
Amortization of deferred charges		229	$ 213	456	$ 433
Deferred cost asset balance		456		456
2016 Coverage Year
Premium Deficiency Reserve Activity [Roll Forward]
Balance at June 30, 2016				176
2016 Coverage Year | Risk Adjustment Settlement
Premium Deficiency Reserve Activity [Roll Forward]
Other long-term assets		133		133		0
Other long-term liabilities		(72)		(72)		0
Total net (liability) asset		61		61		0
2016 Coverage Year | Reinsurance Recoverables
Premium Deficiency Reserve Activity [Roll Forward]
Other long-term assets		86		86		0
Other long-term liabilities		0		0		0
Total net (liability) asset		86		86		0
2016 Coverage Year | Risk Corridor Settlement
Premium Deficiency Reserve Activity [Roll Forward]
Other long-term assets		127		127		0
Other long-term liabilities		0		0		0
Total net (liability) asset		127		127		0
Current Coverage Year
Premium Deficiency Reserve Activity [Roll Forward]
Proceeds from reinsurance recoverable				214
Current Coverage Year | Risk Adjustment Settlement
Premium Deficiency Reserve Activity [Roll Forward]
Premiums receivable		133		133		126
Other current assets		0		0		0
Trade accounts payable and accrued expenses		(238)		(238)		(223)
Net current (liability) asset		(105)		(105)		(97)
Other long-term assets		0		0		10
Total net (liability) asset		(105)		(105)		(87)
Current Coverage Year | Reinsurance Recoverables
Premium Deficiency Reserve Activity [Roll Forward]
Premiums receivable		0		0		0
Other current assets		316		316		610
Trade accounts payable and accrued expenses		0		0		0
Net current (liability) asset		316		316		610
Other long-term assets		0		0		0
Total net (liability) asset		316		316		610
Current Coverage Year | Risk Corridor Settlement
Premium Deficiency Reserve Activity [Roll Forward]
Premiums receivable		0		0		0
Other current assets		0		0		0
Trade accounts payable and accrued expenses		0		0		0
Net current (liability) asset		0		0		0
Other long-term assets		415		415		459
Total net (liability) asset		$ 415		415		$ 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%
Scenario, Forecast | Health Care Reform
Premium Deficiency Reserve Activity [Roll Forward]
Payment of annual health insurance industry fee	$ 912