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Benefit Plans - Pension and postretirement benefits remeasurement gains and losses (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2021 | Mar. 31, 2020
Retirement Benefits [Abstract] |  |
Discount rate | $ (417) | $ (36)
Other assumptions | (114) | (80)
Remeasurement of plan assets (gains) losses | 221 | 434
Pension and other postretirement remeasurement (gains) losses | $ (310) | $ 318

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- Definition Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Remeasurement due to Change in Other Assumptions + References No definition available. + Details
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- Definition Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Remeasurement due to Change in Weighted Average Discount Rate + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
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- Definition Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Remeasurement Plan Assets Gain (Loss) + References No definition available. + Details
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Balance Type: | credit
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- References No definition available. + Details
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- Definition Amount of gain (loss), recognized immediately as component of net periodic benefit (cost) credit, for change in value of benefit obligation or plan assets from experience different from that assumed, change in actuarial assumption, or consequence of temporarily deviating from substantive plan. Includes, but is not limited to, amount in excess of ten percent of greater of fair value of plan assets or benefit obligation. + 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 (h)(4) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e2709-114920 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109237824&loc=SL108413299-114919 + Details
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