Asset Retirement Obligations (Tables)

9 Months Ended

Sep. 30, 2014

Asset Retirement Obligation Disclosure [Abstract]

Change in asset retirement obligations

The following schedule shows the change in our asset retirement obligations for the nine months ended September 30, 2014 (dollars in millions): 

Asset retirement obligations at January 1, 2014	$	347
Changes attributable to:
Accretion expense	18
Settlements	(19		)
Estimated cash flow revisions	44
Asset retirement obligations at September 30, 2014	$	390