FAIR VALUE MEASUREMENTS (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) Institution	Dec. 31, 2015 USD ($) Institution	Dec. 31, 2015 USD ($) item	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($) Institution
Fair value of assets and liabilities measured on recurring basis
Estimated fair value of the long-term debt instrument as a percentage of carrying value	93.90%	96.20%	96.20%	96.20%
Investments impairment	$ 19			$ 2
Impairment charges related to write-down of long-lived assets	$ 14			19	$ 20
Number of hospitals with impairment charges	4	2	2		1
Long-lived assets held and used	$ 163	$ 45	$ 45	45	$ 23
Continuing operations
Fair value of assets and liabilities measured on recurring basis
Impairment charges related to write-down of long-lived assets	54			19
Recurring basis
Fair value of assets and liabilities measured on recurring basis
Marketable debt securities-noncurrent	49	59	59	59
Investments	49	59	59	59
Recurring basis | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair value of assets and liabilities measured on recurring basis
Marketable debt securities-noncurrent	23	24	24	24
Investments	23	24	24	24
Recurring basis | Significant Other Observable Inputs (Level 2)
Fair value of assets and liabilities measured on recurring basis
Marketable debt securities-noncurrent	26	35	35	35
Investments	26	35	35	35
Non-recurring basis
Fair value of assets and liabilities measured on recurring basis
Other than temporarily impaired equity method investments	27
Long-lived assets held and used	163	45	45	45
Non-recurring basis | Significant Other Observable Inputs (Level 2)
Fair value of assets and liabilities measured on recurring basis
Other than temporarily impaired equity method investments	27
Long-lived assets held and used	$ 163	$ 45	$ 45	$ 45