Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Schedule of components of provision for income tax

The components of the income tax expense are as follows:

	Years Ended December 31,
	2021		2020	2019
	(Dollars in millions)
Income tax expense:
Federal
Current	$	5	5	7
Deferred	514		338	376
State
Current	42		50	15
Deferred	72		55	81
Foreign
Current	23		29	35
Deferred	12		(27)	(11)
Total income tax expense	$	668	450	503

	Years Ended December 31,
	2021		2020	2019
	(Dollars in millions)
Income tax expense was allocated as follows:
Income tax expense in the consolidated statements of operations:
Attributable to income	$	668	450	503
Stockholders' equity:
Tax effect of the change in accumulated other comprehensive loss	$	222	17	(62)

Schedule of reconciliation of the statutory federal income tax rate to effective income tax rate

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

	Years Ended December 31,
	2021		2020		2019
	(Percentage of pre-tax income (loss))
Statutory federal income tax rate	21.0	%	21.0	%	21.0	%
State income taxes, net of federal income tax benefit	3.3	%	(10.8)	%	(1.6)	%
Goodwill impairment	—	%	(71.0)	%	(28.6)	%
Change in liability for unrecognized tax position	0.1	%	(0.6)	%	(0.2)	%
Legislative changes to GILTI	—	%	1.8	%	—	%
Nondeductible executive stock compensation	0.2	%	(1.6)	%	(0.1)	%
Change in valuation allowance	—	%	2.6	%	—	%
Net foreign income taxes	0.6	%	(0.6)	%	(0.5)	%
Research and development credits	(0.5)	%	1.6	%	0.1	%
Other, net	—	%	0.1	%	(0.7)	%
Effective income tax rate	24.7	%	(57.5)	%	(10.6)	%

Schedule of components of deferred tax assets and deferred tax 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:

	As of December 31,
	2021		2020
	(Dollars in millions)
Deferred tax assets
Post-retirement and pension benefit costs	$	978	1,164
Net operating loss carryforwards	2,463		3,138
Other employee benefits	96		119
Other	554		604
Gross deferred tax assets	4,091		5,025
Less valuation allowance	(1,566)		(1,538)
Net deferred tax assets	2,525		3,487
Deferred tax liabilities
Property, plant and equipment, primarily due to depreciation differences	(3,941)		(3,882)
Goodwill and other intangible assets	(2,473)		(2,755)
Gross deferred tax liabilities	(6,414)		(6,637)
Net deferred tax liability	$	(3,889)	(3,150)

Summary of NOLs

The U.S. federal net operating loss carryforwards expire as follows:

Expiring	Amount
December 31,	(Dollars in millions)
2026	$	741
2027	375
2028	637
2029	645
2030	668
2031	733
2032	348
2033	238
2037	2,976
NOLs per return	7,361
Uncertain tax positions	(4,457)
Financial NOLs	$	2,904

Summary of the reconciliation of the change in gross unrecognized tax benefits

A reconciliation of the change in our gross unrecognized tax benefits (excluding both interest and any related federal benefit) from January 1 to December 31 for 2021 and 2020 is as follows:

	2021		2020
	(Dollars in millions)
Unrecognized tax benefits at beginning of year	$	1,474	1,538
Increase in tax positions of the current year netted against deferred tax assets	1		18
Increase in tax positions of prior periods netted against deferred tax assets	—		5
Decrease in tax positions of the current year netted against deferred tax assets	(101)		(86)
Decrease in tax positions of prior periods netted against deferred tax assets	(1)		(5)
Increase in tax positions taken in the current year	4		4
Increase in tax positions taken in the prior year	2		1
Decrease due to payments/settlements	(3)		(1)
Decrease from the lapse of statute of limitations	(1)		—
Unrecognized tax benefits at end of year	$	1,375	1,474