v3.26.1
TiO2 segment information - Reconciliation of segment profit (loss) and Consolidated net income (loss) (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
TiO2 segment and geographic information [Line Items]        
Net sales $ 558.1 $ 494.4 $ 1,067.9 $ 984.2
Segment profit 22.9 (5.7) 20.9 20.0
Corporate interest and dividend income 0.3 0.3 0.5 0.7
Marketable equity securities     0.3 (1.0)
Other components of net periodic pension and OPEB cost (0.8) (0.6) (1.6) (1.1)
Interest expense (14.2) (12.8) (28.5) (24.4)
Income tax expense (7.7) (3.5) (10.5) (11.1)
Net income (loss) 15.2 (9.2) 10.4 8.9
Depreciation expense     $ 31.2 29.0
Number of reportable segments not disclosed     true  
Corporate non segment        
TiO2 segment and geographic information [Line Items]        
Corporate expenses (3.2) (3.3) $ (5.6) (6.3)
Corporate interest and dividend income 0.1 0.1 0.2 0.3
Single reportable segment        
TiO2 segment and geographic information [Line Items]        
Depreciation expense 15.8 15.1 31.2 29.0
Single reportable segment | Operating segment        
TiO2 segment and geographic information [Line Items]        
Net sales 558.1 494.4 1,067.9 984.2
Segment profit 41.0 10.9 56.1 52.5
Marketable equity securities     0.3 (1.0)
Other components of net periodic pension and OPEB cost (0.8) (0.6) (1.6) (1.1)
Interest expense (14.2) (12.8) (28.5) (24.4)
Income tax expense $ (7.7) $ (3.5) $ (10.5) $ (11.1)