Fair Value Measurements Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2014

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

The following table provides information for financial assets (liabilities) measured at fair value on a recurring basis as of September 30, 2014 and December 31, 2013:

	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, 2014
Derivative Assets (Liabilities):
Commodity assets	$	—	$	162		$	57		$	219
Commodity liabilities	—		(26		)	(362		)	(388		)
Interest rate liabilities	—		(52		)	—			(52		)
Foreign currency liability	—		(30		)	—			(30		)
Total derivatives	$	—	$	54		$	(305	)	$	(251	)
As of December 31, 2013
Derivative Assets (Liabilities):
Commodity assets	$	—	$	25		$	15		$	40
Commodity liabilities	—		(100		)	(493		)	(593		)
Interest rate liabilities	—		(98		)	—			(98		)
Foreign currency assets	—		2			—			2
Total derivatives	$	—	$	(171	)	$	(478	)	$	(649	)

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, 2014 and December 31, 2013:

	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, 2014
Financial Assets (Liabilities):
Other current assets	$	57		$	—	$	—	$	57
Other current liabilities	(58		)	—		—		(58		)
Total	$	(1	)	$	—	$	—	$	(1	)
As of December 31, 2013
Financial Assets (Liabilities):
Other current assets	$	80		$	—	$	—	$	80
Other current liabilities	(82		)	—		—		(82		)
Total	$	(2	)	$	—	$	—	$	(2	)