BASIS OF PRESENTATION - Description of Business and Basis of Presentation (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020 USD ($) hospital center	Jan. 01, 2020 USD ($)	Dec. 31, 2019 USD ($)
Business Acquisition
Number of hospitals operated by subsidiaries | hospital	65
Number of healthcare facilities | center	510
Accumulated deficit	$ 2,346		$ 2,513
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Cumulative Effect, Period of Adoption, Adjustment
Business Acquisition
Accumulated deficit		$ 14