Quarterly report pursuant to Section 13 or 15(d)

Medical Claims Liability (Narrative) (Details)

v3.7.0.1
Medical Claims Liability (Narrative) (Details) - USD ($)
$ in Millions
6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Insurance [Abstract]    
Short-duration insurance contracts, Incurred but not reported and expected development on reported claims $ 3,124  
Amounts recorded as an adjustment to premium revenues related to minimum HBR and return of premium programs $ 4 $ 16