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Employee Benefit Plans - Schedule of Changes in Benefit Obligation and Fair Value of Plan Assets (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Change in Plan Assets: |  |  |
Fair Value of Plan Assets at Beginning of Plan Year | $ 3,000,000,000 |  |
Non-qualified Employer Contributions | 0 | $ 0 | $ 0
Fair Value of Plan Assets at End of Plan Year | 3,016,000,000 | 3,000,000,000 |
Capitalized service costs | 4,000,000 | 3,000,000 |
Pension Benefits |  |  |
Actuarial Present Value of Benefit Obligation |  |  |
Accumulated Benefit Obligation | 2,909,000,000 | 3,134,000,000 |
Projected Benefit Obligation | 3,022,000,000 | 3,257,000,000 | 3,122,000,000
Change in Projected Benefit Obligation: |  |  |
Projected Benefit Obligation at Beginning of Plan Year | 3,257,000,000 | 3,122,000,000 |
Service Cost | 45,000,000 | 46,000,000 |
Interest Cost | 55,000,000 | 82,000,000 | 103,000,000
Plan Participants' Contributions | 0 | 0 |
Actuarial Loss (Gain) | (142,000,000) | 197,000,000 |
Benefits Paid | (193,000,000) | (190,000,000) |
Benefit Obligation at End of Plan Year | 3,022,000,000 | 3,257,000,000 | 3,122,000,000
Change in Plan Assets: |  |  |
Fair Value of Plan Assets at Beginning of Plan Year | 3,000,000,000 | 2,825,000,000 |
Actual Return on Plan Assets | 187,000,000 | 345,000,000 |
Plan Participants' Contributions | 0 | 0 |
Benefits Paid | (193,000,000) | (190,000,000) |
Fair Value of Plan Assets at End of Plan Year | 3,016,000,000 | 3,000,000,000 | 2,825,000,000
Funded Status at End of Plan Year | (6,000,000) | (257,000,000) |
Pension Benefits | Nonqualified Plan |  |  |
Change in Plan Assets: |  |  |
Non-qualified Employer Contributions | 22,000,000 | 20,000,000 |
Post-retirement Benefits |  |  |
Actuarial Present Value of Benefit Obligation |  |  |
Projected Benefit Obligation | 81,000,000 | 96,000,000 | 117,000,000
Change in Projected Benefit Obligation: |  |  |
Projected Benefit Obligation at Beginning of Plan Year | 96,000,000 | 117,000,000 |
Service Cost | 1,000,000 | 1,000,000 |
Interest Cost | 1,000,000 | 5,000,000 | 2,000,000
Plan Participants' Contributions | 4,000,000 | 6,000,000 |
Actuarial Loss (Gain) | (4,000,000) | (11,000,000) |
Benefits Paid | (17,000,000) | (22,000,000) |
Benefit Obligation at End of Plan Year | 81,000,000 | 96,000,000 | 117,000,000
Change in Plan Assets: |  |  |
Fair Value of Plan Assets at Beginning of Plan Year | 0 | 0 |
Actual Return on Plan Assets | 0 | 0 |
Plan Participants' Contributions | 4,000,000 | 6,000,000 |
Benefits Paid | (17,000,000) | (22,000,000) |
Fair Value of Plan Assets at End of Plan Year | 0 | 0 | $ 0
Funded Status at End of Plan Year | (81,000,000) | (96,000,000) |
Post-retirement Benefits | Nonqualified Plan |  |  |
Change in Plan Assets: |  |  |
Non-qualified Employer Contributions | $ 13,000,000 | $ 16,000,000 |

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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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- Definition Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses. + 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 (b)(1) -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 of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. + 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 (a)(6) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 60 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39716-114964 + 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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- Definition Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=123453770&loc=d3e1703-114919 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920 Reference 3: 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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