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Retirement Benefits (Summary of Changes in the Fair Value of the Plans Level 3 Assets) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Fair value of plan assets at beginning of year | $ 19,074 |
Fair value of plan assets at end of year | 19,394 | $ 19,074
Corporate stocks |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Fair value of plan assets at beginning of year | 2,777 |
Fair value of plan assets at end of year | 2,413 | 2,777
Significant Unobservable Inputs (Level 3) |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Fair value of plan assets at beginning of year | 774 | 683
Purchases | 20 | 20
Sales | (15) | (12)
Unrealized Gain/ (Loss) | (79) | 25
Realized Gain/ (Loss) | 1 | 1
Exchange Rate Impact | (36) | 55
Transfers in/(out) and Other | (2) | 2
Fair value of plan assets at end of year | 663 | 774
Significant Unobservable Inputs (Level 3) | Other investments |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Fair value of plan assets at beginning of year | 773 | 682
Purchases | 19 | 20
Sales | (15) | (12)
Unrealized Gain/ (Loss) | (78) | 25
Realized Gain/ (Loss) | 1 | 1
Exchange Rate Impact | (36) | 55
Transfers in/(out) and Other | (2) | 2
Fair value of plan assets at end of year | 662 | 773
Significant Unobservable Inputs (Level 3) | Corporate stocks |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Fair value of plan assets at beginning of year | 1 | 1
Purchases | 1 | 0
Sales | 0 | 0
Unrealized Gain/ (Loss) | (1) | 0
Realized Gain/ (Loss) | 0 | 0
Exchange Rate Impact | 0 | 0
Transfers in/(out) and Other | 0 | 0
Fair value of plan assets at end of year | $ 1 | $ 1

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- Definition Defined Benefit Plan, Plan Assets Level 3 Reconciliation, Recurring Basis Asset Translation Adjustment + References No definition available. + Details
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- Definition Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan from actual return (loss) on assets sold. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02)(A) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921 + Details
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- Definition Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan from actual return (loss) on assets still held. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02)(A) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921 + Details
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- Definition Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan, for assets transferred into (out of) Level 3 of fair value hierarchy. Includes, but is not limited to, transfer due to change in observability of significant inputs. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02)(C) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 55 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921 + Details
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