v3.26.1
Related Party Transactions (Cost of Sales from Related Parties) (Details) - Affiliated Entity - Westlake - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Feedstock Purchased        
Related Party Transaction [Line Items]        
Charges from related parties in cost of sales $ 86,595 $ 90,567 $ 183,656 $ 176,066
Other service charges        
Related Party Transaction [Line Items]        
Charges from related parties in cost of sales $ 34,748 $ 33,729 $ 72,953 $ 65,206