ACCOUNTS RECEIVABLE AND ALLOWANCE FOR DOUBTFUL ACCOUNTS - Allowance (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Accounts receivable and allowance for doubtful accounts
Allowance for doubtful accounts as a percent of patients accounts receivable			26.80%		25.40%
Self-Pay Patients
Accounts receivable and allowance for doubtful accounts
Allowance for doubtful accounts as a percent of patients accounts receivable			83.00%		80.60%
Estimated costs of caring	$ 167	$ 171	$ 477	$ 503
Managed Care Patients
Accounts receivable and allowance for doubtful accounts
Allowance for doubtful accounts as a percent of patients accounts receivable			9.70%		7.50%
Charity Care Patients
Accounts receivable and allowance for doubtful accounts
Estimated costs of caring	37	50	$ 109	123
Medicai DSH and other supplemental revenues
Accounts receivable and allowance for doubtful accounts
Estimated costs of caring	$ 249	$ 208	$ 691	$ 675