Stockholders' Equity (Tables)

9 Months Ended

Sep. 30, 2012

Table Text Block [Abstract]

Earnings Per Share Table

			Three Months Ended				Nine Months Ended
			September 30,				September 30,
millions except per-share amounts			2012		2011		2012		2011
Net income (loss)
	Net income (loss) attributable to common stockholders		$	121	$	(3,051)	$	2,188	$	(2,291)
	Less: Distributions on participating securities			—		—		1		—
	Less: Undistributed income allocated to participating securities			1		—		13		—
Basic			$	120	$	(3,051)	$	2,174	$	(2,291)
Diluted			$	120	$	(3,051)	$	2,174	$	(2,291)
Shares
	Average number of common shares outstanding—basic			500		498		499		498
	Dilutive effect of stock options and performance-based
		stock awards		2		—		2		—
	Average number of common shares outstanding—diluted			502		498		501		498
	Excluded (1)			6		12		6		12
Net income (loss) per common share
	Basic		$	0.24	$	(6.12)	$	4.35	$	(4.60)
	Diluted		$	0.24	$	(6.12)	$	4.34	$	(4.60)
	Dividends per common share		$	0.09	$	0.09	$	0.27	$	0.27

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(1)Inclusion of certain shares would have had an anti-dilutive effect.