Stockholders' Equity

12 Months Ended

Dec. 31, 2015

Stockholders' Equity Note [Abstract]

Stockholders' Equity

17. Stockholders’ Equity

Common Stock  The following summarizes the changes in the Company’s outstanding shares of common stock:

millions	2015	2014	2013
Shares of common stock issued
Shares at January 1	526	523	519
Exercise of stock options	1	2	2
Issuance of restricted stock	1	1	2
Shares at December 31	528	526	523
Shares of common stock held in treasury
Shares at January 1	19	19	18
Shares received for restricted stock vested and options exercised	1	—	1
Shares at December 31	20	19	19
Shares of common stock outstanding at December 31	508	507	504

The Company’s basic earnings per share (EPS) is computed based on the average number of shares of common stock outstanding for the period and includes the effect of any participating securities and TEUs as appropriate. Diluted EPS includes the effect of the Company’s outstanding stock options, restricted stock awards, restricted stock units, and TEUs, if the inclusion of these items is dilutive.

The following provides a reconciliation between basic and diluted EPS attributable to common stockholders for the years ended December 31:

millions except per-share amounts	2015			2014			2013
Net income (loss)
Net income (loss) attributable to common stockholders	$	(6,692	)	$	(1,750	)	$	801
Less distributions on participating securities	3			4			2
Less undistributed income allocated to participating securities	—			—			4
Basic	$	(6,695	)	$	(1,754	)	$	795
Diluted	$	(6,695	)	$	(1,754	)	$	795
Shares
Average number of common shares outstanding—basic	508			506			502
Dilutive effect of stock options	—			—			3
Average number of common shares outstanding—diluted	508			506			505
Excluded due to anti-dilutive effect	11			11			4
Net income (loss) per common share
Basic	$	(13.18	)	$	(3.47	)	$	1.58
Diluted	$	(13.18	)	$	(3.47	)	$	1.58