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Retirement Plans - Narrative (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2025 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Defined contribution plan, cost |  | $ 28 | $ 27 | $ 24
Railroad retirement system contributions |  | 671 | 711 | 586
CollectiveBargaining Arrangement, Other |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Expensed incurred on premiums paid |  | $ 12 | $ 16 | $ 20
Pension Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Discount rate |  | 5.61% | 5.00% | 5.21%
Loss on pre tax |  | $ 644 | $ 643 |
Defined benefit pension plan |  | $ 3,300 | $ 3,600 |
Expected return on plan assets, changes in fair value, period (in years) |  | 5 years |  |
Expected return on plan assets (as a percent) |  | 5.25% | 5.25% | 6.25%
Asset allocation target, evaluation period (in years) |  | 3 years |  |
Weighted-average maturity of pension plan debt portfolio (in years) |  | 22 years | 22 years |
Other post retirement benefits liability |  | $ (555) | $ (520) |
Other post retirement benefits periodic (benefit)/cost |  | $ (3) | $ 0 | $ 9
Pension Plan | Forecast |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Expected return on plan assets (as a percent) | 5.25% |  |  |
Other Postretirement Benefits Plan |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Discount rate |  | 5.53% | 4.97% |
Other post retirement benefits liability |  | $ 104 | $ 104 |
Other post retirement benefits periodic (benefit)/cost |  | $ (5) | $ (7) | $ (2)
401K Thrift Plan Before 2018 |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer matching contribution (as a percent) |  | 50.00% |  |
Compensation contributed (as a percent) |  | 6.00% |  |
401K Thrift Plan 2018 Beyond |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Employer matching contribution (as a percent) |  | 100.00% |  |
Compensation contributed (as a percent) |  | 6.00% |  |
Contributing annual amount (as a percent) |  | 3.00% |  |

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- Definition Defined Benefit Plan, Plan Assets, Target Allocation, Evaluation Period + References No definition available. + Details
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- Definition Percentage of employees' gross pay for which the employer contributes in addition to the matching contribution to a defined contribution plan. + References No definition available. + Details
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- Definition Represents Railroad Retirement System Agreement. + References No definition available. + Details
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- Definition Represents the weighted-average maturity of the Pension Plan debt portfolio. + References No definition available. + Details
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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 -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -Publisher FASB -URI https://asc.fasb.org/1943274/2147482790/220-10-45-14A Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (j) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-8 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480506/715-20-50-1 + Details
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- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
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