v3.26.1
INVESTMENTS IN UNCONSOLIDATED AFFILIATES - Americas Styrenics (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Investments in Unconsolidated Affiliates          
Investments in unconsolidated affiliate $ 210.2 $ 224.0 $ 210.2 $ 224.0 $ 206.9
AmSty          
Investments in Unconsolidated Affiliates          
Investments in unconsolidated affiliate 210.2   210.2   206.9
Investment in unconsolidated affiliates-difference between carrying amount and underlying equity $ 11.3   $ 11.3   $ 14.2
Percentage of ownership underlying net assets 50.00%   50.00%    
Amortized weighted average remaining useful life     P2Y3M18D    
Dividends received from operating activities $ 0.0 $ 5.0 $ 0.0 $ 5.0