v3.8.0.1
Goodwill and Intangible Assets - Schedule Of Intangible Assets (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]      
Intangible assets $ 1,747 $ 1,751  
Weighted average life in years 11 years 7 months 6 days 11 years 6 months  
Total accumulated amortization $ (349) $ (206)  
Intangible assets, net 1,398 1,545  
Amortization expense 156 147 $ 24
Purchased contract rights      
Finite-Lived Intangible Assets [Line Items]      
Intangible assets $ 1,173 $ 1,171  
Weighted average life in years 12 years 7 months 6 days 12 years 7 months 6 days  
Total accumulated amortization $ (188) $ (95)  
Provider contracts      
Finite-Lived Intangible Assets [Line Items]      
Intangible assets $ 274 $ 285  
Weighted average life in years 11 years 10 months 24 days 10 years 8 months 12 days  
Total accumulated amortization $ (66) $ (55)  
Customer relationships      
Finite-Lived Intangible Assets [Line Items]      
Intangible assets $ 22 $ 22  
Weighted average life in years 8 years 2 months 12 days 8 years 2 months 12 days  
Total accumulated amortization $ (21) $ (21)  
Trade names      
Finite-Lived Intangible Assets [Line Items]      
Intangible assets $ 162 $ 163  
Weighted average life in years 9 years 7 months 6 days 9 years 7 months 6 days  
Total accumulated amortization $ (34) $ (17)  
Developed technologies      
Finite-Lived Intangible Assets [Line Items]      
Intangible assets $ 109 $ 110  
Weighted average life in years 5 years 5 years  
Total accumulated amortization $ (40) $ (18)  
Other Intangibles      
Finite-Lived Intangible Assets [Line Items]      
Intangible assets $ 7 $ 0  
Weighted average life in years 2 years 9 months 18 days