Stockholders' Equity

12 Months Ended

Dec. 31, 2012

Disclosure Text Block [Abstract]

Stockholders' Equity

14.  Stockholders' Equity

Common Stock   In August 2011, the Company terminated its $5.0 billion share-repurchase programunder which shares could be repurchased either in the open market or through privately negotiated transactions. The following summarizes the changes in the Company's outstanding shares of common stock:

millions	2012	2011	2010
Shares of common stock issued
Shares at January 1	516	513	509
Exercise of stock options	1	1	2
Issuance of restricted stock	2	2	2
Shares at December 31	519	516	513
Shares of common stock held in treasury
Shares at January 1	18	17	16
Shares received for restricted stock vested and options exercised	—	1	1
Shares at December 31	18	18	17
Shares of common stock outstanding at December 31	501	498	496

The reconciliation between basic and diluted EPS attributable to common stockholders is as follows:

			Years Ended December 31,
millions except per-share amounts			2012		2011		2010
Net income (loss)
	Net income (loss) attributable to common stockholders		$	2,391	$	(2,649)	$	761
	Less distributions on participating securities			1		—		1
	Less undistributed income allocated to participating securities			14		—		4
	Basic		$	2,376	$	(2,649)	$	756
	Diluted		$	2,376	$	(2,649)	$	756
Shares
	Average number of common shares outstanding—basic			500		498		495
		Dilutive effect of stock options and performance-based stock awards		2		—		2
	Average number of common shares outstanding—diluted			502		498		497
	Excluded (1)			6		12		6
Net income (loss) per common share
	Basic		$	4.76	$	(5.32)	$	1.53
	Diluted		$	4.74	$	(5.32)	$	1.52
	Dividends per common share		$	0.36	$	0.36	$	0.36

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