Debt - Schedule of Total Debt (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Total principal	$ 33,492
Unamortized discount and deferred issuance costs	(1,678)	$ (1,693)
Total debt	31,814	31,192
Less: current portion	(1,520)	(1,425)
Total long-term debt	30,294	29,767
Notes and Debentures
Debt Instrument [Line Items]
Total principal	32,694	32,044
Equipment Obligations
Debt Instrument [Line Items]
Total principal	693	732
Equipment Obligations \| Railroad Assets, Equipment
Debt Instrument [Line Items]
Debt instrument, collateral amount	800	800
Finance Lease
Debt Instrument [Line Items]
Total principal	$ 105	$ 109
Minimum \| Notes and Debentures
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	2.30%
Minimum \| Equipment Obligations
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	2.60%
Minimum \| Finance Lease
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	3.10%
Maximum \| Notes and Debentures
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	7.20%
Maximum \| Equipment Obligations
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	6.20%
Maximum \| Finance Lease
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage	6.80%

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount of long-term debt and lease obligation, classified as noncurrent.

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