Quarterly report pursuant to Section 13 or 15(d)

Segment Information (Details)

v3.7.0.1
Segment Information (Details)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2017
USD ($)
Jun. 30, 2016
USD ($)
Jun. 30, 2017
USD ($)
segment
Jun. 30, 2016
USD ($)
Segment Reporting [Abstract]        
Number of operating segments | segment     2  
Segment Reporting Information [Line Items]        
Total revenues $ 11,954 $ 10,897 $ 23,678 $ 17,850
Earnings from operations 438 377 678 397
Eliminations        
Segment Reporting Information [Line Items]        
Total revenues (2,423) (1,465) (4,767) (2,947)
Managed Care        
Segment Reporting Information [Line Items]        
Total revenues 11,341 10,234 22,456 16,751
Earnings from operations 374 337 561 318
Managed Care | Operating Segments        
Segment Reporting Information [Line Items]        
Total revenues 11,352 10,288 22,478 16,839
Managed Care | Eliminations        
Segment Reporting Information [Line Items]        
Total revenues 11 54 22 88
Specialty Services        
Segment Reporting Information [Line Items]        
Total revenues 613 663 1,222 1,099
Earnings from operations 64 40 117 79
Specialty Services | Operating Segments        
Segment Reporting Information [Line Items]        
Total revenues 3,025 2,074 5,967 3,958
Specialty Services | Eliminations        
Segment Reporting Information [Line Items]        
Total revenues $ 2,412 $ 1,411 $ 4,745 $ 2,859