v3.26.1
Segment Information (Details)
$ in Thousands
3 Months Ended
Mar. 31, 2026
USD ($)
segment
Mar. 31, 2025
USD ($)
Dec. 31, 2025
USD ($)
Segment Reporting Information [Line Items]      
Number of operating segments | segment 1    
Number of reportable segments | segment 1    
Depreciation and amortization $ 34,299 $ 27,068  
Cost of sales 211,916 183,548  
Selling, general and administrative expenses 7,190 7,474  
Interest expense—Westlake 5,085 5,537  
Net income 81,655 42,309  
Assets 1,235,698   $ 1,256,533
Operating Segments | OpCo      
Segment Reporting Information [Line Items]      
Raw material, energy, manufacturing and logistics costs 177,617 156,480  
Depreciation and amortization 34,299 27,068  
Cost of sales 211,916 183,548  
Selling, general and administrative expenses 6,228 6,672  
Other segment items 141 (971)  
Interest expense—Westlake 312 268  
Net income 87,390 48,380  
Assets 1,201,556   1,222,123
Corporate      
Segment Reporting Information [Line Items]      
Interest expense—Westlake 4,773 5,269  
Net income (5,735) $ (6,071)  
Assets $ 34,142   $ 34,410