Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2018

Fair Value Disclosures [Abstract]

Schedule of fair value measurement of financial assets (liabilities) measured at fair value on a recurring basis

The following table provides information for financial assets (liabilities) measured at fair value on a recurring basis as of June 30, 2018 and December 31, 2017:

	Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)			Total Fair Value
			($ in millions)
As of June 30, 2018
Derivative Assets (Liabilities):
Commodity assets	$	—	$	20		$	7		$	27
Commodity liabilities	—		(293		)	(52		)	(345		)
Total derivatives	$	—	$	(273	)	$	(45	)	$	(318	)
As of December 31, 2017
Derivative Assets (Liabilities):
Commodity assets	$	—	$	—		$	8		$	8
Commodity liabilities	—		(20		)	(23		)	(43		)
Total derivatives	$	—	$	(20	)	$	(15	)	$	(35	)

A summary of the changes in the fair values of our financial assets (liabilities) classified as Level 3 during the Current Period and the Prior Period is presented below:

	Commodity Derivatives
	($ in millions)
Balance, as of January 1, 2018	$	(15	)
Total gains (losses) (realized/unrealized):
Included in earnings(a)	(32		)
Total purchases, issuances, sales and settlements:
Settlements	2
Balance, as of June 30, 2018	$	(45	)
Balance, as of January 1, 2017	$	(10	)
Total gains (losses) (realized/unrealized):
Included in earnings(a)	19
Total purchases, issuances, sales and settlements:
Settlements	1
Balance, as of June 30, 2017	$	10

___________________________________________

(a)		Commodity Derivatives
		2018			2017
		($ in millions)
	Total gains (losses) included in earnings for the period	$	(32	)	$	19
	Change in unrealized gains (losses) related to assets still held at reporting date	$	(30	)	$	12

The following table provides fair value measurement information for the above-noted financial assets (liabilities) measured at fair value on a recurring basis as of June 30, 2018 and December 31, 2017:

	Quoted Prices in Active Markets (Level 1)			Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total Fair Value
	($ in millions)
As of June 30, 2018
Financial Assets (Liabilities):
Other current assets	$	53		$	—	$	—	$	53
Other current liabilities	(52		)	—		—		(52		)
Total	$	1		$	—	$	—	$	1
As of December 31, 2017
Financial Assets (Liabilities):
Other current assets	$	57		$	—	$	—	$	57
Other current liabilities	(60		)	—		—		(60		)
Total	$	(3	)	$	—	$	—	$	(3	)