Quarterly report pursuant to Section 13 or 15(d)

Segment Information (Details)

v3.10.0.1
Segment Information (Details)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2018
USD ($)
segment
Sep. 30, 2017
USD ($)
Sep. 30, 2018
USD ($)
Sep. 30, 2017
USD ($)
Segment Reporting [Abstract]        
Number of operating segments | segment 2      
Segment Reporting Information [Line Items]        
Total revenues $ 16,182 $ 11,898 $ 43,557 $ 35,576
Earnings from operations 41 340 1,070 1,018
Eliminations        
Segment Reporting Information [Line Items]        
Total revenues (2,376) (2,378) (6,995) (7,145)
Managed Care        
Segment Reporting Information [Line Items]        
Total revenues 15,446 11,259 41,229 33,737
Earnings from operations 92 238 983 799
Managed Care | Operating Segments        
Segment Reporting Information [Line Items]        
Total revenues 15,420 11,248 41,153 33,704
Managed Care | Eliminations        
Segment Reporting Information [Line Items]        
Total revenues 26 11 76 33
Specialty Services        
Segment Reporting Information [Line Items]        
Total revenues 3,112 3,017 9,323 8,984
Earnings from operations (51) 102 87 219
Specialty Services | Operating Segments        
Segment Reporting Information [Line Items]        
Total revenues 762 650 2,404 1,872
Specialty Services | Eliminations        
Segment Reporting Information [Line Items]        
Total revenues $ 2,350 $ 2,367 $ 6,919 $ 7,112