Income Taxes Income Taxes (Tables)

12 Months Ended

Dec. 31, 2016

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

The components of the income tax provision (benefit) for each of the periods presented below are as follows:



	Years Ended December 31,
	2016			2015			2014
	($ in millions)
Current
Federal	$	(14	)	$	—		$	—
State	(5		)	(36		)	47
Current Income Taxes	(19		)	(36		)	47
Deferred
Federal	(147		)	(4,385		)	1,115
State	(24		)	(42		)	(18		)
Deferred Income Taxes	(171		)	(4,427		)	1,097
Total	$	(190	)	$	(4,463	)	$	1,144

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The effective income tax expense (benefit) differed from the computed "expected" federal income tax expense on earnings before income taxes for the following reasons:



	Years Ended December 31,
	2016			2015			2014
	($ in millions)
Income tax expense (benefit) at the federal statutory rate (35%)	$	(1,606	)	$	(6,684	)	$	1,120
State income taxes (net of federal income tax benefit)	(30		)	(406		)	68
Remeasurement of state deferred tax liabilities	—			—			(114		)
Change in valuation allowance	1,423			2,727			74
Other	23			(100		)	(4		)
Total	$	(190	)	$	(4,463	)	$	1,144

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

The tax-effected temporary differences and tax loss carryforwards which comprise deferred taxes are as follows:



	Years Ended December 31,
	2016			2015
	($ in millions)
Deferred tax liabilities:
Volumetric production payments	$	(223	)	$	(802	)
Derivative instruments	—			(300		)
Other	(62		)	(71		)
Deferred tax liabilities	(285		)	(1,173		)

Deferred tax assets:
Property, plant and equipment	593			1,144
Net operating loss carryforwards	2,587			1,556
Carrying value of debt	539			532
Asset retirement obligations	98			174
Investments	275			260
Derivative instruments	161			—
Accrued liabilities	319			333
Other	118			123
Deferred tax assets	4,690			4,122
Valuation allowance	(4,389		)	(2,949		)
Net deferred tax assets	301			1,173
Net deferred tax assets^(a)	$	16		$	—

___________________________________________


(a)	The net deferred tax assets are included in other long-term assets in the accompanying balance sheets.

Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]

A reconciliation of the beginning and ending balances of unrecognized tax benefits is as follows:



	2016			2015			2014
	($ in millions)
Unrecognized tax benefits at beginning of period	$	280		$	303		$	644
Additions based on tax positions related to the current year	—			27			13
Additions to tax positions of prior years	33			—			—
Settlements	(111		)	—			—
Reductions to tax positions of prior years	—			(50		)	(354		)
Unrecognized tax benefits at end of period	$	202		$	280		$	303