v3.26.3
SEGMENT INFORMATION (Details 1)
$ in Millions
 3 Months Ended 9 Months Ended 64 Months Ended
Sep. 30, 2026
USD ($)
Jun. 30, 2026
USD ($)
Mar. 31, 2026
USD ($)
Sep. 30, 2025
USD ($)
Jun. 30, 2025
USD ($)
Mar. 31, 2025
USD ($)
Sep. 30, 2026
USD ($)
sEGMENT
Sep. 30, 2025
USD ($)
Jun. 30, 2026
USD ($)
Dec. 31, 2025
USD ($)
Gross Margin [Abstract]                    
Sales $ 1,747.7     $ 1,713.2     $ 5,072.6 $ 5,115.7    
Cost of goods sold 1,575.0     1,529.8     4,653.9 4,645.5    
Gross Profit 172.7     183.4     418.7 470.2    
Income (Loss) before Income Taxes [Abstract]                    
Segment Reporting, Other Segment Item, Amount (99.3)     (99.1)     (349.4) (296.7)    
Restructuring charges (1.7) $ (10.5) $ (9.1) (2.9) $ (7.4) $ (4.0) (21.3) (14.3) $ (281.2)  
Other Operating Income 0.3     0.4     0.4 0.2    
Interest Expense, Operating and Nonoperating (44.5)     (45.2)     (130.9) (138.1)    
Non-operating pension income 3.3     4.9     9.4 15.5    
Income (loss) before taxes 17.1     41.5     (97.4) 36.8    
Depreciation and amortization expense                    
Depreciation and amortization 114.4     133.8     353.7 395.9    
Assets                    
Assets 7,405.7     7,600.9     $ 7,405.7 7,600.9   $ 7,325.8
Number of Reportable Segments | sEGMENT             3      
United States                    
Gross Margin [Abstract]                    
Sales 1,223.3     1,136.1     $ 3,580.3 3,475.2    
Europe                    
Gross Margin [Abstract]                    
Sales 142.1     159.3     446.0 462.7    
Other foreign                    
Gross Margin [Abstract]                    
Sales 382.3     417.8     1,046.3 1,177.8    
Chlor Alkali Products and Vinyls                    
Gross Margin [Abstract]                    
Sales 850.8     924.0     2,427.2 2,828.0    
Cost of goods sold 742.7     758.0     2,196.3 2,431.8    
Gross Profit 108.1     166.0     230.9 396.2    
Income (Loss) before Income Taxes [Abstract]                    
Segment Reporting, Other Segment Item, Amount (36.8)     (38.4)     (150.7) (125.4)    
Restructuring charges 0.0     0.0     0.0 0.0 (155.3)  
Other Operating Income 0.0     0.0     0.0 0.0    
Interest Expense, Operating and Nonoperating 0.0     0.0     0.0 0.0    
Non-operating pension income 0.0     0.0     0.0 0.0    
Income (loss) before taxes 71.3     127.6     80.2 270.8    
Depreciation and amortization expense                    
Depreciation and amortization 91.1     109.0     282.4 322.5    
Assets                    
Assets 5,060.1     5,203.8     5,060.1 5,203.8    
Chlor Alkali Products and Vinyls | United States                    
Gross Margin [Abstract]                    
Sales 577.8     624.7     1,687.0 1,935.8    
Chlor Alkali Products and Vinyls | Europe                    
Gross Margin [Abstract]                    
Sales 36.0     48.4     95.7 123.6    
Chlor Alkali Products and Vinyls | Other foreign                    
Gross Margin [Abstract]                    
Sales 237.0     250.9     644.5 768.6    
Epoxy                    
Gross Margin [Abstract]                    
Sales 412.2     349.6     1,189.9 1,012.5    
Cost of goods sold 396.7     367.4     1,131.1 1,052.5    
Gross Profit 15.5     (17.8)     58.8 (40.0)    
Income (Loss) before Income Taxes [Abstract]                    
Segment Reporting, Other Segment Item, Amount (14.9)     (14.4)     (45.1) (44.3)    
Restructuring charges 0.0     0.0     0.0 0.0 $ (122.8)  
Other Operating Income 0.0     0.0     0.0 0.0    
Interest Expense, Operating and Nonoperating 0.0     0.0     0.0 0.0    
Non-operating pension income 0.0     0.0     0.0 0.0    
Income (loss) before taxes 0.6     (32.2)     13.7 (84.3)    
Depreciation and amortization expense                    
Depreciation and amortization 11.1     13.2     34.7 39.1    
Assets                    
Assets 922.1     923.8     922.1 923.8    
Epoxy | United States                    
Gross Margin [Abstract]                    
Sales 208.7     139.5     557.1 424.4    
Epoxy | Europe                    
Gross Margin [Abstract]                    
Sales 102.1     88.1     304.8 283.3    
Epoxy | Other foreign                    
Gross Margin [Abstract]                    
Sales 101.4     122.0     328.0 304.8    
Winchester                    
Gross Margin [Abstract]                    
Sales 484.7     439.6     1,455.5 1,275.2    
Cost of goods sold 428.5     398.5     1,306.2 1,143.7    
Gross Profit 56.2     41.1     149.3 131.5    
Income (Loss) before Income Taxes [Abstract]                    
Segment Reporting, Other Segment Item, Amount (22.4)     (21.8)     (72.2) (64.4)    
Restructuring charges 0.0     0.0     0.0 0.0    
Other Operating Income 0.0     0.0     0.0 0.0    
Interest Expense, Operating and Nonoperating 0.0     0.0     0.0 0.0    
Non-operating pension income 0.0     0.0     0.0 0.0    
Income (loss) before taxes 33.8     19.3     77.1 67.1    
Depreciation and amortization expense                    
Depreciation and amortization 9.0     7.8     26.7 25.2    
Assets                    
Assets 838.7     924.5     838.7 924.5    
Winchester | United States                    
Gross Margin [Abstract]                    
Sales 436.8     371.9     1,336.2 1,115.0    
Winchester | Europe                    
Gross Margin [Abstract]                    
Sales 4.0     22.8     45.5 55.8    
Winchester | Other foreign                    
Gross Margin [Abstract]                    
Sales 43.9     44.9     73.8 104.4    
Corporate/ other                    
Gross Margin [Abstract]                    
Sales 0.0     0.0     0.0 0.0    
Cost of goods sold 7.1     5.9     20.3 17.5    
Gross Profit (7.1)     (5.9)     (20.3) (17.5)    
Income (Loss) before Income Taxes [Abstract]                    
Segment Reporting, Other Segment Item, Amount (25.2)     (24.5)     (81.4) (62.6)    
Restructuring charges (1.7)     (2.9)     (21.3) (14.3)    
Other Operating Income 0.3     (0.4)     0.4 (0.2)    
Interest Expense, Operating and Nonoperating 44.5     45.2     130.9 138.1    
Non-operating pension income 3.3     4.9     9.4 15.5    
Income (loss) before taxes (88.6)     (73.2)     (268.4) (216.8)    
Depreciation and amortization expense                    
Depreciation and amortization 3.2     3.8     9.9 9.1    
Assets                    
Assets 584.8     548.8     584.8 548.8    
Corporate/ other | United States                    
Gross Margin [Abstract]                    
Sales 0.0     0.0     0.0 0.0    
Corporate/ other | Europe                    
Gross Margin [Abstract]                    
Sales 0.0     0.0     0.0 0.0    
Corporate/ other | Other foreign                    
Gross Margin [Abstract]                    
Sales $ 0.0     $ 0.0     $ 0.0 $ 0.0