Nature of Operations and Significant Accounting Policies (Details) $ in Millions			1 Months Ended	3 Months Ended
	Jun. 18, 2021 shares	Jun. 04, 2021	Apr. 30, 2021 USD ($)	Mar. 31, 2022 USD ($) state mi	Dec. 31, 2021 USD ($)		Mar. 31, 2021 USD ($)	Jun. 30, 2021 USD ($)	Mar. 26, 2021 USD ($) property phase
Revenue from External Customer [Line Items]
Number of rail route miles | mi				19,500
Number of states rail network serves | state				23
Proceeds from property dispositions				$ 8			$ 0
Gain recognized on property dispositions				27			$ 3
Stock split conversion ratio		3
Number of additional shares of common stock received for each share held after stock split (in shares) | shares	2
Reclassification to other capital				(11,284)	$ (11,630)	[1]
Reclassification from retained earnings				103	66	[1]		$ 0
Revision of Prior Period, Reclassification, Adjustment | Stock split reclassification adjustment
Revenue from External Customer [Line Items]
Reclassification to other capital								1,000
Reclassification from retained earnings								$ 1,000
Virginia Line Segments
Revenue from External Customer [Line Items]
Number of property rights for sale | property									3
Number of phases to complete property rights sale transaction | phase									3
Total sale price									$ 525
Proceeds from property dispositions			$ 200		$ 200
Gain recognized on property dispositions			$ 349	$ 20

[1] Certain prior year data has been retroactively adjusted to reflect the stock split effective June 28, 2021 or reclassified to conform to the current presentation. See accompanying notes to consolidated financial statements.