Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Dec. 31, 2013

Income Tax Disclosure [Abstract]

Schedule of components of provision for income tax

	Years Ended December 31,
	2014			2013		2012
	(Dollars in millions)
Income tax expense was as follows:
Federal
Current	$	18		1		57
Deferred	305			403		361
State
Current	26			62		15
Deferred	(14		)	(8	)	33
Foreign
Current	3			9		7
Deferred	—			(4	)	—
Total income tax expense	$	338		463		473

Schedule of income tax expense allocation

	Years Ended December 31,
	2014			2013		2012
	(Dollars in millions)
Income tax expense was allocated as follows:
Income tax expense in the consolidated statements of operations:
Attributable to income	$	338		463		473
Stockholders' equity:
Compensation expense for tax purposes in excess of amounts recognized for financial reporting purposes	(5		)	(14	)	(18	)
Tax effect of the change in accumulated other comprehensive loss	(744		)	554		(434	)

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,
	2014		2013		2012
	(Percentage of pre-tax income)
Statutory federal income tax rate	35.0	%	35.0	%	35.0	%
State income taxes, net of federal income tax benefit	2.7	%	2.8	%	2.5	%
Impairment of goodwill	—	%	188.5	%	—	%
Reversal of liability for unrecognized tax position	0.4	%	(24.5	)%	—	%
Foreign income taxes	0.4	%	2.7	%	0.3	%
Nondeductible accounting adjustment for life insurance	—	%	3.1	%	—	%
Release state valuation allowance	—	%	(2.3	)%	—	%
Loss on worthless investment in foreign subsidiary	(5.4	)%	—	%	—	%
Other, net	(2.6	)%	1.4	%	—	%
Effective income tax rate	30.5	%	206.7	%	37.8	%

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,
	2014			2013
	(Dollars in millions)
Deferred tax assets
Post-retirement and pension benefit costs	$	2,276		1,618
Net operating loss carryforwards	1,091			1,532
Other employee benefits	214			182
Other	602			782
Gross deferred tax assets	4,183			4,114
Less valuation allowance	(409		)	(435	)
Net deferred tax assets	3,774			3,679
Deferred tax liabilities
Property, plant and equipment, primarily due to depreciation differences	(3,869		)	(3,904	)
Goodwill and other intangible assets	(2,908		)	(3,226	)
Other	(147		)	(137	)
Gross deferred tax liabilities	(6,924		)	(7,267	)
Net deferred tax liability	$	(3,150	)	(3,588	)

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 2014 and 2013 is as follows:

	2014			2013
	(Dollars in millions)
Unrecognized tax benefits at beginning of year	$	14		78
Increase in tax positions taken in the prior year	9			—
Decrease due to the reversal of tax positions taken in a prior year	(2		)	—
Decrease from the lapse of statute of limitations	(1		)	(36	)
Settlements	(3		)	(28	)
Unrecognized tax benefits at end of year	$	17		14

Schedule of open income tax years by major jurisdiction

Our open income tax years by major jurisdiction are as follows at December 31, 2014:

Jurisdiction	Open Tax Years
Federal	2010—current
State
Florida	2010—current
Minnesota	2011—current
Other states	2010—current