Investment in Affiliates and Related-Party Transactions - Schedule of Related Party in the Consolidated Income Statement Components (Details) - Materials, Supplies and Other - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Corporate Joint Venture \| Conrail
Related Party Amounts Consolidated Income Statements [Abstract]
Rents, fees and services	$ 126	$ 119	$ 117
Purchase price amortization and other	4	4	4
Equity earnings in affiliates	(49)	(42)	(43)
Total expense	81	81	78
Affiliated Entity \| TTX
Related Party Amounts Consolidated Income Statements [Abstract]
Car hire rents	219	223	223
Equity earnings in affiliates	(51)	(56)	(60)
Total expense	$ 168	$ 167	$ 163

Car Hire Rents

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- Definition

The amortization of the fair value write-up of fixed assets when the original purchase price from the acquisition was allocated based on fair value.

+ References

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Related Party Amounts Consolidated Income Statements [Abstract]

+ References

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- Definition

Total amount of related party rents, fees and services in the Company's consolidated income statements.

+ References

No definition available.

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- Definition

Amount of income (loss) for proportionate share of equity method investee's income (loss).

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Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

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