Income Taxes (Tables)

12 Months Ended

Dec. 31, 2015

Income Tax Disclosure [Abstract]

Summary of open income tax years by jurisdiction

Our open income tax years by major jurisdiction are as follows at December 31, 2015:

Jurisdiction	Open Tax Years
Federal	2012—current
State
Arizona	2010—current
Florida	2010—current
Other states	2011—current

Schedule of components of the income tax expense from continuing operations

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

	Years Ended December 31,
	2015			2014		2013
	(Dollars in millions)
Income tax expense:
Current tax provision:
Federal and foreign	$	734		738		653
State and local	114			129		101
Total current tax provision	848			867		754
Deferred tax expense:
Federal and foreign	(170		)	(209	)	(125	)
State and local	(19		)	(19	)	(27	)
Total deferred tax expense	(189		)	(228	)	(152	)
Income tax expense	$	659		639		602

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

The effective income tax rate for continuing operations differs from the statutory tax rate as follows:

	Years Ended December 31,
	2015		2014		2013
	(in percent)
Effective income tax rate:
Federal statutory income tax rate	35.0	%	35.0	%	35.0	%
State income taxes-net of federal effect	3.6	%	4.0	%	3.1	%
Other	(0.6	)%	0.7	%	0.3	%
Effective income tax rate	38.0	%	39.7	%	38.4	%

Schedule of components of the deferred tax assets and liabilities

The components of the deferred tax assets and liabilities are as follows:

	As of December 31,
	2015			2014
	(Dollars in millions)
Deferred tax assets and liabilities:
Deferred tax liabilities:
Property, plant and equipment	$	(1,431	)	(1,380	)
Intangibles assets	(1,153		)	(1,449	)
Receivable from an affiliate due to pension plan participation	(460		)	(500	)
Other	(59		)	(52	)
Total deferred tax liabilities	(3,103		)	(3,381	)
Deferred tax assets:
Payable to affiliate due to post-retirement benefit plan participation	921			998
Debt premiums	21			36
Other	277			274
Total deferred tax assets	1,219			1,308
Valuation allowance on deferred tax assets	(12		)	(12	)
Net deferred tax assets	1,207			1,296
Net deferred tax liabilities	$	(1,896	)	(2,085	)