Income Taxes (Tables)

12 Months Ended

Dec. 31, 2025

Income Tax Disclosure [Abstract]

Schedule of components of the income tax expense from continuing operations

The components of the Income tax expense from continuing operations are as follows:

	Year Ended December 31,
	2025
	(Dollars in millions)
Loss (income) before income taxes
Domestic	$	(987)
Foreign	12
Total pre-tax book loss	$	(975)
Income tax expense
Current tax expense
Federal	$	181
State and Local	40
Foreign	6
Total current tax expense	227
Deferred tax expenses
Federal	104
State and Local	21
Total deferred tax expense	125
Income tax expense
Federal	285
State and Local	61
Foreign	6
Total income tax expense	$	352

	Years Ended December 31,
	2024		2023
	(Dollars in millions)
Income tax expense:
Federal and foreign
Current	$	396	432
Deferred	34		19
State and local
Current	94		107
Deferred	3		3
Income tax expense	$	527	561

Schedule of effective income tax rate for continuing operations that differs from the statutory tax rate

The following is a reconciliation from the statutory federal income tax rate to our effective income tax rate:

	Year Ended December 31,
	2025
	(Dollars in millions)		Percentage of pre-tax loss
Statutory federal income tax rate	$	(205)	21.0	%
Federal
Effect of cross-border tax laws
Other	(1)		0.1	%
Tax Credits
Other	—		—	%
Changes in valuation allowance	—		—	%
Nontaxable or nondeductible items
Goodwill impairment	421		(43.2)	%
Loss on disposal group held for sale (Note 3)	50		(5.1)	%
Other	(1)		0.1	%
State income taxes, net of federal income tax benefit(1)	47		(4.8)	%
Change in liability for unrecognized tax position	25		(2.6)	%
Foreign tax effect
India
Deferred tax on unremitted earnings	13		(1.3)	%
Other	3		(0.3)	%
Effective income tax rate	$	352	(36.1)	%

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(1)During the year ended December 31, 2025, state taxes in Minnesota, Colorado and Arizona comprised greater than 50% of the tax effect in this category.

	Years Ended December 31,
	2024		2023
	(Percentage of pre-tax income)
Effective income tax rate:
Federal statutory income tax rate	21.0	%	21.0	%
State income taxes-net of federal effect	3.7	%	(31.3)	%
Goodwill impairment	—	%	(187.2)	%
Change in liability for unrecognized tax position	1.5	%	(8.9)	%
Other	—	%	(1.4)	%
Effective income tax rate	26.2	%	(207.8)	%

Schedule of components of the deferred tax assets and liabilities

The tax effects of temporary differences that gave rise to significant portions of the deferred tax assets and deferred tax liabilities were as follows:

	December 31,
	2025		2024
	(Dollars in millions)
Deferred tax liabilities:
Property, plant and equipment	$	(1,623)	(1,524)
Intangible assets	(90)		(83)
Other	(52)		(40)
Total deferred tax liabilities	(1,765)		(1,647)
Deferred tax assets:
Payable to affiliate due to post-retirement benefit plan participation	306		312
Other	—		1
Gross deferred tax assets	306		313
Net deferred tax assets	306		313
Net deferred tax liabilities	$	(1,459)	(1,334)

Schedule of income taxes paid

Income taxes paid, net are as follows:

	Year Ended December 31,
	2025
	(Dollars in millions)
Federal	$	154
State	39
Foreign	6
Total income taxes paid, net(1)	$	199

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(1)During the year ended December 31, 2025, there were no individual jurisdictions with cash taxes paid that equaled or exceeded 5% of the total income taxes paid.

Reconciliation of unrecognized tax benefits

A reconciliation of the change in our gross unrecognized tax benefits (excluding both interest and any related federal benefit) for the years ended December 31, 2025 and 2024 are as follows:

	Years ended December 31,
	2025		2024
	(Dollars in millions)
Unrecognized tax benefits at beginning of period	$	293	317
Increase (decrease) due to tax positions taken in a prior year	1		(11)
Decrease due to tax positions taken in a current year	(4)		(13)
Unrecognized tax benefits at end of period	$	290	293