Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2015

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

The following table provides information for financial assets (liabilities) measured at fair value on a recurring basis as of September 30, 2015 and December 31, 2014:

	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 September 30, 2015
Derivative Assets (Liabilities):
Commodity assets	$	—	$	343		$	39		$	382
Commodity liabilities	—		(12		)	(116		)	(128		)
Interest rate liabilities	—		—			—			—
Foreign currency liabilities	—		(76		)	—			(76		)
Supply contract assets	—		—			291			291
Total derivatives	$	—	$	255		$	214		$	469
As of December 31, 2014
Derivative Assets (Liabilities):
Commodity assets	$	—	$	784		$	205		$	989
Commodity liabilities	—		(9		)	(259		)	(268		)
Interest rate liabilities	—		(17		)	—			(17		)
Foreign currency liabilities	—		(53		)	—			(53		)
Supply contract assets	—		—			1			1
Total derivatives	$	—	$	705		$	(53	)	$	652

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 September 30, 2015 and December 31, 2014:

	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 September 30, 2015
Financial Assets (Liabilities):
Other current assets	$	58		$	—	$	—	$	58
Other current liabilities	(60		)	—		—		(60		)
Total	$	(2	)	$	—	$	—	$	(2	)
As of December 31, 2014
Financial Assets (Liabilities):
Other current assets	$	57		$	—	$	—	$	57
Other current liabilities	(58		)	—		—		(58		)
Total	$	(1	)	$	—	$	—	$	(1	)