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Employee Benefit Plans - Schedule of Allocation of Plan Assets (Details) - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020
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Defined Benefit Plan Disclosure [Line Items] |  |
Amount | $ 3,016 | $ 3,000
Percent of Total Assets | 100.00% | 100.00%
Growth-Oriented |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Amount | $ 1,812 | $ 1,816
Percent of Total Assets | 60.00% | 61.00%
Equity |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Amount | $ 1,559 | $ 1,324
Percent of Total Assets | 52.00% | 44.00%
Fixed Income |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Amount | $ 204 | $ 271
Percent of Total Assets | 7.00% | 9.00%
Cash and Cash Equivalents |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Amount | $ 49 | $ 221
Percent of Total Assets | 1.00% | 8.00%
Immunizing |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Amount | $ 1,204 | $ 1,184
Percent of Total Assets | 40.00% | 39.00%
Fixed Income |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Amount | $ 1,145 | $ 1,018
Percent of Total Assets | 38.00% | 34.00%
Cash and Cash Equivalents |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Amount | $ 59 | $ 166
Percent of Total Assets | 2.00% | 5.00%

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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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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