Quarterly report pursuant to Section 13 or 15(d)

Segment Information (Details)

v3.8.0.1
Segment Information (Details)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2017
USD ($)
Sep. 30, 2016
USD ($)
Sep. 30, 2017
USD ($)
segment
Sep. 30, 2016
USD ($)
Segment Reporting [Abstract]        
Number of operating segments | segment     2  
Segment Reporting Information [Line Items]        
Total revenues $ 11,898 $ 10,846 $ 35,576 $ 28,696
Earnings from operations 340 342 1,018 739
Eliminations        
Segment Reporting Information [Line Items]        
Total revenues (2,378) (1,580) (7,145) (4,527)
Managed Care        
Segment Reporting Information [Line Items]        
Total revenues 11,248 10,175 33,704 26,926
Earnings from operations 238 309 799 627
Managed Care | Operating Segments        
Segment Reporting Information [Line Items]        
Total revenues 11,259 10,231 33,737 27,070
Managed Care | Eliminations        
Segment Reporting Information [Line Items]        
Total revenues 11 56 33 144
Specialty Services        
Segment Reporting Information [Line Items]        
Total revenues 650 671 1,872 1,770
Earnings from operations 102 33 219 112
Specialty Services | Operating Segments        
Segment Reporting Information [Line Items]        
Total revenues 3,017 2,195 8,984 6,153
Specialty Services | Eliminations        
Segment Reporting Information [Line Items]        
Total revenues $ 2,367 $ 1,524 $ 7,112 $ 4,383