Earnings per Share

3 Months Ended

Mar. 31, 2015

Earnings Per Share [Abstract]

Earnings per Share

Earnings per Share

The Company has unvested shares of restricted stock and restricted stock units outstanding that are considered participating securities and, therefore, computes basic and diluted earnings per share under the two-class method. Basic earnings per share for the periods are based upon the weighted average number of shares of common stock outstanding during the periods. Diluted earnings per share include the effect of certain stock options.

	Three Months Ended March 31,
	2015			2014
Net income attributable to Westlake Chemical Corporation	$	146,342		$	158,032
Less:
Net income attributable to participating securities	(200		)	(384		)
Net income attributable to common shareholders	$	146,142		$	157,648

The following table reconciles the denominator for the basic and diluted earnings per share computations shown in the consolidated statements of operations:

	Three Months Ended March 31,
	2015		2014
Weighted average common shares—basic	132,714,566		133,072,254
Plus incremental shares from:
Assumed exercise of options	490,740		540,670
Weighted average common shares—diluted	133,205,306		133,612,924
Earnings per common share attributable to Westlake Chemical Corporation :
Basic	$	1.10	$	1.18
Diluted	$	1.10	$	1.18

Excluded from the computation of diluted earnings per share are options to purchase 241,312 and 69,662 shares of common stock for the three months ended March 31, 2015 and 2014, respectively. These options were outstanding during the periods reported but were excluded because the effect of including them would have been antidilutive.