Impairments (Tables)

12 Months Ended

Dec. 31, 2013

Investments, Debt and Equity Securities [Abstract]

Details of Impairment of Long-Lived Assets Held and Used by Asset [Table Text Block]

A summary of our impairments of fixed assets by asset class and other charges for the years ended December 31, 2013, 2012 and 2011 is as follows:

	Years Ended December 31,
	2013		2012		2011
	($ in millions)
Buildings and land	$	366	$	248	$	3
Drilling rigs and equipment	71		60		—
Gathering systems	22		6		43
Other	87		26		—
Total impairments of fixed assets and other	$	546	$	340	$	46