v3.8.0.1
Acquisitions and Noncontrolling Interest - Redeemable Noncontrolling Interest (Details)
$ in Millions
12 Months Ended
Dec. 31, 2017
USD ($)
Reconciliation of Changes in the Redeemable Noncontrolling Interest [Roll Forward]  
Redeemable noncontrolling interest, beginning balance $ 145
Noncontrolling interest purchased related to USMM (115)
Contribution from noncontrolling interest 2
Net losses attributable to noncontrolling interests (20)
Redeemable noncontrolling interest, ending balance $ 12