Fair value measurements and financial instruments - Additional Information (Details) $ in Millions |
Jun. 30, 2026
USD ($)
|
Jun. 30, 2026
EUR (€)
|
Dec. 31, 2025
USD ($)
|
Dec. 31, 2025
EUR (€)
|
|---|---|---|---|---|
| Fair value measurements and financial instruments | ||||
| Total debt | $ 587.5 | $ 591.7 | ||
| Kronos Worldwide | 9.50% Senior Secured Notes due 2029 | Kronos International, Inc | ||||
| Fair value measurements and financial instruments | ||||
| Interest rate | 9.50% | 9.50% | 9.50% | 9.50% |
| Estimated market price of the notes | € | € 986 | € 937 | ||
| Principal amount of debt instrument | € | € 1,000 | € 1,000 | ||
| Total debt | $ 487.7 | $ 503.7 | ||
| VALHI, INC. | Contran Credit Facility | ||||
| Fair value measurements and financial instruments | ||||
| Total debt | $ 7.6 | $ 23.6 |