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Retirement Benefits (Narrative) (Details) $ in Millions |  | 1 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jan. 01, 2017 | Nov. 30, 2019 GBP (£) | Dec. 31, 2021 USD ($) shares | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($)
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Assumed health care cost trend rate for Medicare eligibles and non-Medicare eligibles |  |  | 4.94% |  |
Future assumed health care cost trend rate |  |  | 4.36% |  |
Automatic employer contribution of employee's eligible base pay (as a percent) | 4.00% |  |  |  |
401(k) Plan's assets invested in common stock |  |  | $ 742 | $ 537 |
Pension Benefits |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Rate of compensation increase (for expense)* |  |  | 1.85% | 1.76% |
Post-retirement Benefits |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Rate of compensation increase (for expense)* |  |  | 0.00% | 0.00% |
U.S. |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Expected employer contributions, next fiscal year |  |  | $ 31 |  |
Cost of defined contribution plans |  |  | $ 150 | $ 145 | $ 139
U.S. | Pension and Postretirement Benefits |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Assumed health care cost trend rate for Medicare eligibles and non-Medicare eligibles |  |  | 5.50% |  |
Future assumed health care cost trend rate |  |  | 4.00% |  |
Cap on employer share of health care trend (as a percent) |  |  | 5.00% |  |
U.S. | Pension Benefits |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Accumulated benefit obligation for plans with accumulated benefit obligations in excess of plan assets |  |  | $ 6,600 | 6,900 |
Aggregate fair value of plan assets for plans with accumulated benefit obligations in excess of plan assets |  |  | 5,500 | 5,100 |
Projected benefit obligation for plans with projected benefit obligations in excess of plan assets |  |  | 6,600 | 6,900 |
Fair value of plan assets for plans with projected benefit obligations in excess of plan assets |  |  | 5,500 | 5,100 |
Employer contributions |  |  | $ 35 | 65 |
U.S. | Post-retirement Benefits |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Number of shares held in defined benefit plan (in shares) | shares |  |  | 2,000,000 |  |
Change in plan assets (as a percent) |  |  | 6.30% |  |
Employer contributions |  |  | $ 3 | 3 |
U.S. | Equities and equity alternatives |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Target asset allocation percentage |  |  | 60.00% |  |
Actual asset allocation percentage |  |  | 65.00% |  |
U.S. | Equities and equity alternatives | Minimum |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Target asset allocation percentage |  |  | 56.00% |  |
U.S. | Equities and equity alternatives | Maximum |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Target asset allocation percentage |  |  | 64.00% |  |
U.S. | Fixed income |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Target asset allocation percentage |  |  | 40.00% |  |
Actual asset allocation percentage |  |  | 35.00% |  |
U.S. | Fixed income | Minimum |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Target asset allocation percentage |  |  | 36.00% |  |
U.S. | Fixed income | Maximum |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Target asset allocation percentage |  |  | 44.00% |  |
Non-U.S. |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Accumulated benefit obligation for plans with accumulated benefit obligations in excess of plan assets |  |  | $ 1,600 | 3,100 |
Aggregate fair value of plan assets for plans with accumulated benefit obligations in excess of plan assets |  |  | 1,200 | 2,500 |
Projected benefit obligation for plans with projected benefit obligations in excess of plan assets |  |  | 1,700 | 3,300 |
Fair value of plan assets for plans with projected benefit obligations in excess of plan assets |  |  | $ 1,200 | $ 2,600 |
Non-U.S. | Pension Benefits |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Rate of compensation increase (for expense)* |  |  | 2.84% | 2.75% |
Non-cash settlement charges |  |  | $ 5 | $ 3 | 7
Expected employer contributions, next fiscal year |  |  | 147 |  |
Employer contributions |  |  | $ 95 | $ 78 |
Non-U.S. | Post-retirement Benefits |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Rate of compensation increase (for expense)* |  |  | 0.00% | 0.00% |
Employer contributions |  |  | $ 3 | $ 2 |
United Kingdom |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Cost of defined contribution plans |  |  | 141 | $ 121 | $ 100
United Kingdom | Pension Plan Funded Status Guarantee |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Annual deficit contributions (GBP) | £ |  | £ 450,000,000 |  |  |
Annual deficit contributions, period |  | 7 years |  |  |
United Kingdom | Pension Benefits |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Expected employer contributions, next fiscal year |  |  | 112 |  |
Employer contributions |  |  | $ 38 |  |
Period between legally-prescribed negotiations between the Company and the plans' trustee |  |  | 3 years |  |
United Kingdom | Equities and equity alternatives |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Target asset allocation percentage |  |  | 26.00% |  |
Actual asset allocation percentage |  |  | 28.00% |  |
United Kingdom | Equities and equity alternatives | Minimum |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Target asset allocation percentage |  |  | 23.00% |  |
United Kingdom | Equities and equity alternatives | Maximum |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Target asset allocation percentage |  |  | 29.00% |  |
United Kingdom | Fixed income |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Target asset allocation percentage |  |  | 74.00% |  |
Actual asset allocation percentage |  |  | 72.00% |  |
United Kingdom | Fixed income | Minimum |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Target asset allocation percentage |  |  | 71.00% |  |
United Kingdom | Fixed income | Maximum |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Target asset allocation percentage |  |  | 77.00% |  |
United Kingdom Pension and Postretirement Benefit Plan, Defined Benefit | United Kingdom | Geographic Concentration Risk |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Concentration risk (as a percent) |  |  | 81.00% |  |

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