Basis of Presentation and Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2016

Accounting Policies [Abstract]

Schedule of Accounts, Notes, Loans and Financing Receivable

Accounts receivable as of December 31, 2016 and 2015 are detailed below.

	December 31,
	2016			2015
	($ in millions)
Oil, natural gas and NGL sales	$	840		$	696
Joint interest	156			230
Other	93			226
Allowance for doubtful accounts	(32		)	(23		)
Total accounts receivable, net	$	1,057		$	1,129

Schedule of Capitalized Costs of Unproved Properties Excluded from Amortization

The table below sets forth the cost of unproved properties excluded from the amortization base as of December 31, 2016 and the year in which the associated costs were incurred.

	Year of Acquisition
	2016		2015		2014		Prior		Total
	($ in millions)
Leasehold cost	$	109	$	99	$	507	$	2,956	$	3,671
Exploration cost	24		36		13		34		107
Capitalized interest	194		201		184		445		1,024
Total	$	327	$	336	$	704	$	3,435	$	4,802

Schedule of Adoption of New Accounting Pronouncements, Debt Issuance Costs

The retrospective adjustment to the December 31, 2015 consolidated balance sheet is shown below.

	As Previously Reported		December 31, 2015 Adjustment Effect			As Adjusted
	($ in millions)
Other long-term assets	$	333	$	(43	)	$	290
Long-term debt, net	$	10,354	$	(43	)	$	10,311

Schedule of Revisions to Fair Value of Debt

The following table reflects the revisions made.

	As Previously Reported				December 31, 2015 Adjustment Effect						As Revised
	Carrying Amount		Estimated Fair Value		Carrying Amount			Estimated Fair Value			Carrying Amount		Estimated Fair Value
	($ in millions)
Short-term debt (Level 1)	$	381	$	366	$	—		$	—		$	381	$	366
Long-term debt (Level 1)(a)	$	10,347	$	3,735	$	(3,627	)	$	(1,189	)	$	6,720	$	2,546
Long-term debt (Level 2)	$	—	$	—	$	3,584		$	1,189		$	3,584	$	1,189

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(a)    The difference in the carrying amount is due to the debt issuance costs retrospective change noted above.