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Retirement Benefits (Reconciliation of Net Actuarial Loss) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Pension Plan |  |  |
Reconciliation of unrecognized net actuarial gain loss [Roll Forward] |  |  |
Total recognized as component of net periodic benefit credit | $ (181) | $ (130) | $ (62)
Postretirement Benefits |  |  |
Reconciliation of unrecognized net actuarial gain loss [Roll Forward] |  |  |
Total recognized as component of net periodic benefit credit | 1 | 6 | 9
United States | Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent | Pension Plan |  |  |
Reconciliation of unrecognized net actuarial gain loss [Roll Forward] |  |  |
Beginning balance | (1,766) | (1,720) |
Amortization of net loss | 55 | 37 |
Other | 0 | 0 |
Liability experience | 502 | (538) |
Asset experience | (687) | 455 |
Total amount recognized as change in plan assets and benefit obligations | (185) | (83) |
Ending balance, December 31 | (1,896) | (1,766) | (1,720)
United States | Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent | Postretirement Benefits |  |  |
Reconciliation of unrecognized net actuarial gain loss [Roll Forward] |  |  |
Beginning balance | 6 | 11 |
Amortization of net loss | (1) | (1) |
Other | 0 | (1) |
Liability experience | 1 | (3) |
Asset experience | 0 | 0 |
Total amount recognized as change in plan assets and benefit obligations | 1 | (4) |
Ending balance, December 31 | 6 | 6 | 11
Foreign Plan | Pension Plan |  |  |
Reconciliation of unrecognized net actuarial gain loss [Roll Forward] |  |  |
Total recognized as component of net periodic benefit credit | (114) | (74) | (127)
Other | 0 | (13) |
Foreign Plan | Postretirement Benefits |  |  |
Reconciliation of unrecognized net actuarial gain loss [Roll Forward] |  |  |
Total recognized as component of net periodic benefit credit | 1 | 2 | 5
Other | 0 | 0 |
Foreign Plan | Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent | Pension Plan |  |  |
Reconciliation of unrecognized net actuarial gain loss [Roll Forward] |  |  |
Beginning balance | (2,646) | (3,081) |
Amortization of net loss | 91 | 130 |
Effect of settlement | 42 | 54 |
Total recognized as component of net periodic benefit credit | 133 | 184 |
Liability experience | 450 | 149 |
Asset experience | (648) | 311 |
Plan amendments | 3 | (5) |
Effect of curtailment | 0 | 1 |
Total amount recognized as change in plan assets and benefit obligations | (195) | 456 |
Exchange rate adjustments | 140 | (205) |
Ending balance, December 31 | (2,568) | (2,646) | (3,081)
Foreign Plan | Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent | Postretirement Benefits |  |  |
Reconciliation of unrecognized net actuarial gain loss [Roll Forward] |  |  |
Beginning balance | (10) | (11) |
Amortization of net loss | 0 | 1 |
Effect of settlement | 0 | 0 |
Total recognized as component of net periodic benefit credit | 0 | 1 |
Liability experience | 8 | 0 |
Asset experience | 0 | 0 |
Plan amendments | 0 | 0 |
Effect of curtailment | 0 | 0 |
Total amount recognized as change in plan assets and benefit obligations | 8 | 0 |
Exchange rate adjustments | 1 | 0 |
Ending balance, December 31 | $ (1) | $ (10) | $ (11)

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