Asset Retirement Obligations (Tables)

6 Months Ended

Jun. 30, 2012

Asset Retirement Obligation Disclosure [Abstract]

Schedule of Change in Asset Retirement Obligation [Table Text Block]

A reconciliation of the asset retirement obligations for the six months ended June 30, 2012 follows (in millions):

Asset retirement obligations at December 31, 2011	$	1,442
Accretion	45
Revision in estimated cash flows	1
Liabilities settled	(1		)
Asset retirement obligations at June 30, 2012	$	1,487