Pension And Postretirement Benefits (Employee Benefit Obligation Amounts Recognized) (Details) - USD ($) $ in Millions |
Dec. 31, 2020 |
Dec. 31, 2019 |
|---|---|---|
| Defined Benefit Plan Disclosure [Line Items] | ||
| Pension obligations and other postemployment obligations | $ 1,415 | $ 1,528 |
| Pension Benefits | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Current portion of employee benefit obligation | 0 | 0 |
| Employee benefit obligation | (7,552) | (6,343) |
| Net amount recognized | (7,552) | (6,343) |
| Pension Benefits | International | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Pension obligations and other postemployment obligations | 553 | |
| Postretirement Benefits | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Current portion of employee benefit obligation | (1,213) | (1,365) |
| Employee benefit obligation | (8,872) | (10,531) |
| Net amount recognized | (10,085) | $ (11,896) |
| Postretirement Benefits | International | ||
| Defined Benefit Plan Disclosure [Line Items] | ||
| Pension obligations and other postemployment obligations | $ 1,299 |