v3.7.0.1
Debt Total Debt (Details) - USD ($)
$ in Millions
Jun. 30, 2017
Dec. 31, 2016
Debt Instrument [Line Items]    
Total debt $ 3,829 $ 4,109
Unamortized issuance costs (50) (55)
Current maturities 1 1
Debt, Net of Current Maturities and Unamortized Issuance Costs $ 3,778 $ 4,053