Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Taxes [Abstract]

Schedule of Components of Income Tax Expense (Benefit)

Income tax expense (benefit) was as follows (in millions):

	Years ended December 31,
	2021		2020		2019
Current:
Federal	$	1,173	$	1,111	$	989
State	252		231		226
Total current	1,425		1,342		1,215
Deferred:
Federal	422		256		470
State	24		33		84
Total deferred	446		289		554
Total	$	1,871	$	1,631	$	1,769

Schedule of Effective Income Tax Rate Reconciliation

Reconciliation of the U.S. federal statutory income tax rate to the effective tax rate was as follows:

	Years ended December 31,
	2021		2020		2019
U.S. Federal statutory income tax rate	21.0	%	21.0	%	21.0	%
State income taxes, net of federal tax benefit	2.8		3.0		3.4
Effective tax rate	23.8	%	24.0	%	24.4	%

Schedule of Deferred Tax Assets and Liabilities

The components of deferred tax assets and liabilities were as follows (in millions):

	December 31, 2021		December 31, 2020
Deferred tax liabilities:
Property and equipment	$	(14,953)	$	(14,622)
Operating lease right-of-use assets	(314)		(393)
Other	(621)		(489)
Total deferred tax liabilities	(15,888)		(15,504)
Deferred tax assets:
Operating lease liabilities	315		386
Compensation and benefits	202		165
Casualty and environmental	105		104
Other	110		223
Total deferred tax assets	732		878
Net deferred tax liability	$	(15,156)	$	(14,626)

Schedule of Unrecognized Tax Benefits Roll Forward

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in millions):

	Years ended December 31,
	2021		2020		2019
Beginning balance	$	41	$	46	$	50
Additions for tax positions related to current year	9		7		8
Additions (reductions) for tax positions taken in prior years	—		(2)		(6)
Additions (reductions) for tax positions as a result of:
Settlements	—		(3)		—
Lapse of statute of limitations	(4)		(7)		(6)
Ending balance	$	46	$	41	$	46