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Retirement Benefits (Reconciliation of Net Actuarial Loss) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Pension Benefits |  |  |
Recognized as component of net periodic benefit cost (credit): |  |  |
Total recognized as component of net periodic benefit cost (credit) | $ (222) | $ (234) | $ (181)
Post-retirement Benefits |  |  |
Recognized as component of net periodic benefit cost (credit): |  |  |
Total recognized as component of net periodic benefit cost (credit) | 1 | 0 | 1
U.S. | Pension Benefits |  |  |
Recognized as component of net periodic benefit cost (credit): |  |  |
Other | 0 | (49) |
U.S. | Post-retirement Benefits |  |  |
Recognized as component of net periodic benefit cost (credit): |  |  |
Other | 1 | 0 |
U.S. | Net Actuarial (Loss) Gain | Pension Benefits |  |  |
Reconciliation of unrecognized net actuarial gain loss [Roll Forward] |  |  |
Beginning balance | (2,114) | (1,896) |
Recognized as component of net periodic benefit cost (credit): |  |  |
Amortization of net loss | 72 | 44 |
Liability experience | (650) | (753) |
Asset experience | 246 | 491 |
Total amount recognized as change in plan assets and benefit obligations | (404) | (262) |
Ending balance | (2,446) | (2,114) | (1,896)
U.S. | Net Actuarial (Loss) Gain | Post-retirement Benefits |  |  |
Reconciliation of unrecognized net actuarial gain loss [Roll Forward] |  |  |
Beginning balance | 4 | 6 |
Recognized as component of net periodic benefit cost (credit): |  |  |
Amortization of net loss | 0 | (1) |
Liability experience | (1) | (1) |
Asset experience | 0 | 0 |
Total amount recognized as change in plan assets and benefit obligations | (1) | (1) |
Ending balance | 3 | 4 | 6
Non-U.S. | Pension Benefits |  |  |
Recognized as component of net periodic benefit cost (credit): |  |  |
Total recognized as component of net periodic benefit cost (credit) | (162) | (176) | (114)
Non-U.S. | Post-retirement Benefits |  |  |
Recognized as component of net periodic benefit cost (credit): |  |  |
Total recognized as component of net periodic benefit cost (credit) | 0 | 0 | 1
Non-U.S. | Net Actuarial (Loss) Gain | Pension Benefits |  |  |
Reconciliation of unrecognized net actuarial gain loss [Roll Forward] |  |  |
Beginning balance | (3,055) | (2,568) |
Recognized as component of net periodic benefit cost (credit): |  |  |
Amortization of net loss | 89 | 60 |
Effect of settlement | 3 | 7 |
Total recognized as component of net periodic benefit cost (credit) | 92 | 67 |
Liability experience | (1,273) | (1,339) |
Asset experience | 916 | 847 |
Total amount recognized as change in plan assets and benefit obligations | (357) | (492) |
Exchange rate adjustments | (147) | (62) |
Ending balance | (3,467) | (3,055) | (2,568)
Non-U.S. | Net Actuarial (Loss) Gain | Post-retirement Benefits |  |  |
Reconciliation of unrecognized net actuarial gain loss [Roll Forward] |  |  |
Beginning balance | (5) | (1) |
Recognized as component of net periodic benefit cost (credit): |  |  |
Amortization of net loss | 0 | 0 |
Effect of settlement | 0 | 0 |
Total recognized as component of net periodic benefit cost (credit) | 0 | 0 |
Liability experience | (10) | (3) |
Asset experience | 0 | 0 |
Total amount recognized as change in plan assets and benefit obligations | (10) | (3) |
Exchange rate adjustments | (1) | (1) |
Ending balance | $ (16) | $ (5) | $ (1)

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