Condensed Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions |
Sep. 30, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Statement of Financial Position [Abstract] | ||
| Receivables, allowance for doubtful accounts | $ 46 | $ 46 |
| Property, accumulated depreciation | $ 3,921 | $ 3,927 |