Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Schedule of income tax provision

Our income tax provision consisted of the following:

	Year Ended December 31,
(in millions)	2017			2016			2015
Current tax (provision) benefit:
Federal	$	(4	)	$	—		$	(23	)
State and local	5			(28		)	(25		)
International	(54		)	(12		)	(2		)
Deferred tax provision:
Federal	(1,911		)	(2,080		)	(2,409		)
State and local	(160		)	(143		)	(172		)
Income tax provision	$	(2,124	)	$	(2,263	)	$	(2,631	)

Schedule of effective income tax rate reconciliation

The following table presents the principal reasons for the difference between the effective tax rate and the U.S. federal statutory income tax rate:

	Year Ended December 31,
	2017		2016		2015
U.S. federal statutory income tax rate	35.0	%	35.0	%	35.0	%
State taxes, net of federal benefit	1.8		1.8		1.8
Decrease in valuation allowance	—		—		(0.2	)
Foreign tax rate differential	(2.2	)	(2.0	)	—
Tax Cuts and Jobs Act adjustment	2.6		—		—
Other	—		(0.7	)	0.2
Effective income tax rate	37.2	%	34.1	%	36.8	%

Schedule of deferred taxes

The following table shows significant components of our deferred tax assets and liabilities:

	December 31,
(in millions)	2017			2016
Deferred tax assets:
Net operating loss carryforwards	$	1,440		$	2,485
Pension, postretirement and other benefits	2,545			5,259
Alternative minimum tax credit carryforward	379			379
Deferred revenue	1,024			1,544
Other	746			1,075
Valuation allowance	(19		)	(40		)
Total deferred tax assets	$	6,115		$	10,702
Deferred tax liabilities:
Depreciation	$	3,936		$	5,701
Intangible assets	1,070			1,691
Other	174			246
Total deferred tax liabilities	$	5,180		$	7,638
Net deferred tax assets	$	935		$	3,064