Consolidated Statements of Operations (Unaudited) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Net sales	$ 2,357	$ 1,932
Cost of sales	1,848	1,649
Gross profit	509	283
Selling, general and administrative expenses	136	120
Amortization of intangibles	27	27
Income from operations	346	136
Other income (expense)
Interest expense	(33)	(31)
Other income, net	12	11
Income before income taxes	325	116
Provision for (benefit from) income taxes	72	(41)
Net income	253	157
Net income attributable to noncontrolling interests	11	12
Net income attributable to Westlake Chemical Corporation	$ 242	$ 145
Earnings per common share attributable to Westlake Chemical Corporation:
Basic (in dollars per share)	$ 1.88	$ 1.13
Diluted (in dollars per share)	$ 1.87	$ 1.13
Weighted average common shares outstanding:
Basic (in shares)	127,955,532	128,237,364
Diluted (in shares)	128,483,373	128,442,972

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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