Earnings and Dividends per Share (Reconciliation of Denominator for Basic and Diluted Earnings Per Share) (Details) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Earnings and Dividends Per Share [Abstract]
Weighted average common shares—basic	128,341,132	128,142,997	128,206,988	128,049,852
Weighted Average Number Diluted Shares Outstanding Adjustment	999,964	734,863	927,258	631,924
Weighted average common shares-diluted	129,341,096	128,877,860	129,134,246	128,681,776
Earnings per share attributable to Westlake Chemical Corporation: Basic (in dollars per share)	$ 6.65	$ 4.06	$ 12.52	$ 5.94
Earnings per share attributable to Westlake Chemical Corporation: Diluted (in dollars per share)	$ 6.60	$ 4.04	$ 12.43	$ 5.91