(Accounts And Notes Receivable) (Details) - USD ($) $ in Millions |
Dec. 31, 2019 |
Dec. 31, 2018 |
|---|---|---|
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Accounts and notes receivable | $ 3,280 | $ 3,521 |
| Trade | ||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Accounts and notes receivable | 3,020 | 3,249 |
| Other | ||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Accounts and notes receivable | $ 260 | $ 272 |