ACCOUNTS RECEIVABLE AND ALLOWANCE FOR DOUBTFUL ACCOUNTS - Allowance (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Accounts receivable and allowance for doubtful accounts
Allowance for doubtful accounts as a percent of patients accounts receivable	26.80%		27.10%
Self-Pay Patients
Accounts receivable and allowance for doubtful accounts
Allowance for doubtful accounts as a percent of patients accounts receivable	84.70%		85.40%
Estimated costs of caring	$ 160	$ 165
Managed Care Patients
Accounts receivable and allowance for doubtful accounts
Allowance for doubtful accounts as a percent of patients accounts receivable	10.30%		9.90%
Charity Care Patients
Accounts receivable and allowance for doubtful accounts
Estimated costs of caring	$ 30	44
Medicai DSH and other supplemental revenues
Accounts receivable and allowance for doubtful accounts
Estimated costs of caring	$ 158	$ 227