Related Party Transactions (Cost of Sales from Related Parties) (Details) - Affiliated Entity - Westlake - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Related Party Transaction [Line Items]
Charges from related parties in cost of sales	$ 201,746	$ 113,958
Feedstock Purchased
Related Party Transaction [Line Items]
Charges from related parties in cost of sales	162,279	82,116
Other service charges
Related Party Transaction [Line Items]
Charges from related parties in cost of sales	$ 39,467	$ 31,842