Long-term debt - Kronos 3.75 Senior Secured Notes - Additional Information (Detail) € in Millions, $ in Millions	Jun. 30, 2024 USD ($)	Jun. 30, 2024 EUR (€)	Feb. 12, 2024	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
Carrying value of notes	$ 498.2			$ 546.5
Kronos Worldwide, Inc. | 3.75% Senior Secured Notes due September 15, 2025 | Kronos International, Inc
Debt Instrument [Line Items]
Debt instrument interest rate	3.75%	3.75%	3.75%	3.75%
Aggregate principal amount outstanding | €		€ 75
Carrying value of notes	$ 80.2			$ 440.9