Earnings and Dividends per Share (Reconciliation of Denominator for Basic and Diluted Earnings Per Share) (Details) - $ / shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Earnings and Dividends Per Share [Abstract]
Weighted average common shares—basic	128,071,355	127,955,532
Weighted Average Number Diluted Shares Outstanding Adjustment	853,744	527,841
Weighted average common shares-diluted	128,925,099	128,483,373
Earnings per share attributable to Westlake Chemical Corporation: Basic (in dollars per share)	$ 5.87	$ 1.88
Earnings per share attributable to Westlake Chemical Corporation: Diluted (in dollars per share)	$ 5.83	$ 1.87