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Pension and Other Postretirement Benefit Plans - Fair Values of Pension Plan Assets (Details) - Pension Benefits - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | --- | ---
Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | $ 943 | $ 942 |
United States |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 13,067 | 12,672 | $ 11,361
United States | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 292 | 308 |
United States | Developed markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 4,035 | 4,090 |
United States | Emerging markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 919 | 1,096 |
United States | Mortgage and asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 89 |
United States | Developed markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 2,915 | 2,819 |
United States | Government and agency obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 2,870 | 2,236 |
United States | Corporate obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 2,005 | 1,994 |
United States | Mortgage and asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 23 | 33 |
United States | Other |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 8 | 7 |
United States | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 3,156 | 3,199 |
United States | Level 1 | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 3 | 5 |
United States | Level 1 | Developed markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 236 | 206 |
United States | Level 1 | Emerging markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 169 |
United States | Level 1 | Mortgage and asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 1 | Developed markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 2,915 | 2,819 |
United States | Level 1 | Government and agency obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 1 | Corporate obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 1 | Mortgage and asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 1 | Other |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 2 | 0 |
United States | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 4,898 | 4,352 |
United States | Level 2 | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 2 | Developed markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 2 | Emerging markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 2 | Mortgage and asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 89 |
United States | Level 2 | Developed markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 2 | Government and agency obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 2,870 | 2,236 |
United States | Level 2 | Corporate obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 2,005 | 1,994 |
United States | Level 2 | Mortgage and asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 23 | 33 |
United States | Level 2 | Other |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 6 | 7 | 9
United States | Level 3 | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 3 | Developed markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 3 | Emerging markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 3 | Mortgage and asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 3 | Real estate, Investment funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 | 0
United States | Level 3 | Developed markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 3 | Government and agency obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 3 | Corporate obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 3 | Mortgage and asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | Level 3 | Insurance contracts |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 | 0
United States | Level 3 | Other |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 6 | 7 | 9
United States | NAV |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 5,007 | 5,114 |
United States | NAV | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 289 | 303 |
United States | NAV | Developed markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 3,799 | 3,884 |
United States | NAV | Emerging markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 919 | 927 |
United States | NAV | Mortgage and asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | NAV | Developed markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | NAV | Government and agency obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | NAV | Corporate obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | NAV | Mortgage and asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
United States | NAV | Other |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 12,195 | 12,009 | 10,135
International | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 110 | 131 |
International | Developed markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 4,944 | 4,879 |
International | Emerging markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 209 | 246 |
International | Government and agency obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 4,436 | 4,302 |
International | Corporate obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 188 | 189 |
International | Other fixed income obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 26 | 24 |
International | Real estate, Investment funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 17 | 16 |
International | Developed markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 369 | 505 |
International | Government and agency obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 597 | 487 |
International | Corporate obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 225 | 177 |
International | Mortgage and asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 90 | 70 |
International | Insurance contracts |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 982 | 978 |
International | Other |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 2 | 5 |
International | Level 1 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 1,387 | 2,779 |
International | Level 1 | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 82 | 110 |
International | Level 1 | Developed markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 531 | 475 |
International | Level 1 | Emerging markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 137 | 154 |
International | Level 1 | Government and agency obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 240 | 1,516 |
International | Level 1 | Corporate obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 9 | 5 |
International | Level 1 | Other fixed income obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 15 | 9 |
International | Level 1 | Real estate, Investment funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | Level 1 | Developed markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 369 | 505 |
International | Level 1 | Government and agency obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 3 | 3 |
International | Level 1 | Corporate obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 1 |
International | Level 1 | Mortgage and asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | Level 1 | Insurance contracts |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | Level 1 | Other |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 1 | 1 |
International | Level 2 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 9,293 | 7,696 |
International | Level 2 | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 10 | 1 |
International | Level 2 | Developed markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 4,292 | 4,286 |
International | Level 2 | Emerging markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | Level 2 | Government and agency obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 4,025 | 2,614 |
International | Level 2 | Corporate obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 8 | 12 |
International | Level 2 | Other fixed income obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 8 | 11 |
International | Level 2 | Real estate, Investment funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 1 | 1 |
International | Level 2 | Developed markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | Level 2 | Government and agency obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 591 | 481 |
International | Level 2 | Corporate obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 223 | 174 |
International | Level 2 | Mortgage and asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 90 | 70 |
International | Level 2 | Insurance contracts |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 44 | 42 |
International | Level 2 | Other |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 1 | 4 |
International | Level 3 |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 937 | 935 | 851
International | Level 3 | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | Level 3 | Developed markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | Level 3 | Emerging markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | Level 3 | Government and agency obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | Level 3 | Corporate obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | Level 3 | Other fixed income obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | Level 3 | Real estate, Investment funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 | 0
International | Level 3 | Developed markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | Level 3 | Government and agency obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | Level 3 | Corporate obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | Level 3 | Mortgage and asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | Level 3 | Insurance contracts |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 937 | 935 | 851
International | Level 3 | Other |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 | $ 0
International | NAV |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 578 | 599 |
International | NAV | Cash and cash equivalents |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 18 | 20 |
International | NAV | Developed markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 121 | 118 |
International | NAV | Emerging markets equities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 72 | 92 |
International | NAV | Government and agency obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 171 | 172 |
International | NAV | Corporate obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 171 | 172 |
International | NAV | Other fixed income obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 3 | 4 |
International | NAV | Real estate, Investment funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 16 | 15 |
International | NAV | Developed markets |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | NAV | Government and agency obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 3 | 3 |
International | NAV | Corporate obligations |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 2 | 2 |
International | NAV | Mortgage and asset-backed securities |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 0 | 0 |
International | NAV | Insurance contracts |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | 1 | 1 |
International | NAV | Other |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Fair value of plan assets | $ 0 | $ 0 |

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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. + 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)(01) -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 50 -Paragraph 1 -Subparagraph (d)(iv)(01) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 4: 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 Reference 5: 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) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 7: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(ii) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 + Details
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