| **Benefit Plans (Funded Status) (Details) - USD ($) $ in Millions**                                                  | 12 Months Ended |
|----------------------------------------------------------------------------------------------------------------------|-----------------|
||
| **Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]**                                                |            |   |   |
| Actuarial (gain) loss                                                                                                | $ 261           | $ (187) |   |
| **Amounts recognized on the Consolidated Balance Sheets as of December 31:**                                         |            |   |   |
| Other assets                                                                                                         | 2,285           | 2,025 |   |
| Pension Benefits                                                                                                     |            |   |   |
| **Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]**                                                |            |   |   |
| Balance at beginning of period                                                                                       | 2,466           | 2,749 |   |
| Service cost                                                                                                         | 0               | 0 | $ 0 |
| Interest cost                                                                                                        | 100             | 93 | 103 |
| Participants' contributions                                                                                          | 0               | 0 |   |
| Actuarial (gain) loss                                                                                                | 261             | (187) |   |
| Benefits paid                                                                                                        | (169)           | (166) |   |
| Foreign currency translation and other                                                                               | 3               | (7) |   |
| Settlements                                                                                                          | 0               | (16) |   |
| Balance at end of period                                                                                             | 2,661           | 2,466 | 2,749 |
| **Change in plan assets:**                                                                                           |            |   |   |
| Balance beginning of period                                                                                          | 2,025           | 2,261 |   |
| Actual return on plan assets                                                                                         | 292             | (69) |   |
| Company contributions                                                                                                | 134             | 23 |   |
| Participants' contributions                                                                                          | 0               | 0 |   |
| Benefits paid                                                                                                        | (169)           | (166) |   |
| Foreign currency translation and other                                                                               | 3               | (8) |   |
| Settlements                                                                                                          | 0               | (16) |   |
| Balance end of period                                                                                                | 2,285           | 2,025 | 2,261 |
| **Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]**                                                |            |   |   |
| Funded status                                                                                                        | (376)           | (441) |   |
| **Amounts recognized on the Consolidated Balance Sheets as of December 31:**                                         |            |   |   |
| Other assets                                                                                                         | 5               | 9 |   |
| Other liabilities                                                                                                    | (381)           | (450) |   |
| Net amount recognized                                                                                                | (376)           | (441) |   |
| **Amounts recognized in Accumulated other comprehensive income, not yet recognized in net periodic cost (benefit):** |            |   |   |
| Prior service credit                                                                                                 | 0               | 0 |   |
| Net actuarial (gain) loss                                                                                            | 1,056           | 984 |   |
| Net amount recognized                                                                                                | 1,056           | 984 |   |
| Postretirement Benefits                                                                                              |            |   |   |
| **Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]**                                                |            |   |   |
| Balance at beginning of period                                                                                       | 9               | 11 |   |
| Service cost                                                                                                         | 0               | 0 |   |
| Interest cost                                                                                                        | 0               | 0 |   |
| Participants' contributions                                                                                          | 4               | 3 |   |
| Actuarial (gain) loss                                                                                                | 1               | 0 |   |
| Benefits paid                                                                                                        | (6)             | (5) |   |
| Foreign currency translation and other                                                                               | 0               | 0 |   |
| Settlements                                                                                                          | 0               | 0 |   |
| Balance at end of period                                                                                             | 8               | 9 | 11 |
| **Change in plan assets:**                                                                                           |            |   |   |
| Balance beginning of period                                                                                          | 0               | 0 |   |
| Actual return on plan assets                                                                                         | 0               | 0 |   |
| Company contributions                                                                                                | 2               | 2 |   |
| Participants' contributions                                                                                          | 4               | 3 |   |
| Benefits paid                                                                                                        | (6)             | (5) |   |
| Foreign currency translation and other                                                                               | 0               | 0 |   |
| Settlements                                                                                                          | 0               | 0 |   |
| Balance end of period                                                                                                | 0               | 0 | $ 0 |
| **Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]**                                                |            |   |   |
| Funded status                                                                                                        | (8)             | (9) |   |
| **Amounts recognized on the Consolidated Balance Sheets as of December 31:**                                         |            |   |   |
| Other assets                                                                                                         | 0               | 0 |   |
| Other liabilities                                                                                                    | (8)             | (9) |   |
| Net amount recognized                                                                                                | (8)             | (9) |   |
| **Amounts recognized in Accumulated other comprehensive income, not yet recognized in net periodic cost (benefit):** |            |   |   |
| Prior service credit                                                                                                 | 0               | 0 |   |
| Net actuarial (gain) loss                                                                                            | (2)             | (3) |   |
| Net amount recognized                                                                                                | $ (2)           | $ (3) |   |

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| - Definition
Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).
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| - Definition
Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, before tax, of accumulated other comprehensive (income) loss for cost (credit) of benefit change attributable to participants' prior service from plan amendment or plan initiation of defined benefit plan, that has not been recognized in net periodic benefit cost (credit).
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| - Definition
Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.
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| - Definition
Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.
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| - Definition
Amount of asset (liability), recognized in statement of financial position, for defined benefit pension and other postretirement plans.
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| - Definition
Amount of asset, recognized in statement of financial position, for overfunded defined benefit pension and other postretirement plans.
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| - Definition
Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.
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| - Definition
Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.
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| - Definition
Amount of contributions received by defined benefit plan from participant which increase benefit obligation.
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| - Definition
A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of contribution received by defined benefit plan from employer which increases plan assets.
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.
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| - Definition
Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.
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| - Definition
Amount of cost recognized for passage of time related to defined benefit plan.
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of payment to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.
+ References
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| - Definition
Amount of contributions received by defined benefit plan from participant which increases plan assets.
+ References
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.
+ References
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| - Definition
Amount of (increase) decrease to benefit obligation of defined benefit plan from irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Includes, but is not limited to, lump-sum cash payment to participant in exchange for right to receive specified benefits, purchase of nonparticipating annuity contract and change from remeasurement.
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| - Definition
Amount of payment, which decreases plan assets of defined benefit plan, for irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Transaction constituting settlement includes, but is not limited to, making lump-sum cash payment to participant in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contract.
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans.
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