REDEEMABLE NONCONTROLLING INTERESTS IN EQUITY OF CONSOLIDATED SUBSIDIARIES - Segment Details (Details) - Redeemable noncontrolling interests - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Dec. 31, 2016
REDEEMABLE NONCONTROLLING INTEREST        
Redeemable noncontrolling interests $ 1,942 $ 2,430 $ 1,866 $ 2,393
Net income attributable to redeemable noncontrolling interests 61 53    
Hospital Operations and other        
REDEEMABLE NONCONTROLLING INTEREST        
Redeemable noncontrolling interests 526   519  
Net income attributable to redeemable noncontrolling interests 6 4    
Ambulatory Care        
REDEEMABLE NONCONTROLLING INTEREST        
Redeemable noncontrolling interests 1,186   1,137  
Net income attributable to redeemable noncontrolling interests 35 35    
Conifer        
REDEEMABLE NONCONTROLLING INTEREST        
Redeemable noncontrolling interests 230   $ 210  
Net income attributable to redeemable noncontrolling interests $ 20 $ 14