NET OPERATING REVENUES - Ambulatory Care (Details) - Hospital Operations and other - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Disaggregation of Revenue [Line Items]    
Net operating revenues $ 498 $ 455
Net patient service revenues less provision for doubtful accounts    
Disaggregation of Revenue [Line Items]    
Net operating revenues 469 428
Management fees    
Disaggregation of Revenue [Line Items]    
Net operating revenues 23 21
Revenue from other sources    
Disaggregation of Revenue [Line Items]    
Net operating revenues $ 6 $ 6