v3.22.0.1

Pension and Other Postretirement Benefits - Pension Plan Benefit Obligations (Details) - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
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The aggregate projected benefit obligation and fair value of plan assets for defined benefit pension plans with projected benefit obligations in excess of plan assets was as follows: |  |  |
Projected benefit obligation | $ 2,472 | $ 3,795 |
Fair value of plan assets | 1,747 | 2,444 |
Pension benefits​ |  |  |
The projected benefit obligation and accumulated benefit obligation for all defined benefit pension plans was as follows: |  |  |
Projected benefit obligation | 2,817 | 4,081 | $ 142
Accumulated benefit obligation | 2,807 | 4,068 |
The aggregate accumulated benefit obligation and fair value of plan assets for defined benefit pension plans with accumulated benefit obligations in excess of plan assets was as follows: |  |  |
Accumulated benefit obligation | 2,464 | 3,784 |
Fair value of plan assets | $ 1,747 | $ 2,444 |

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- Definition Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level. + 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 (e) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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