Long-term debt - Kronos 3.75 Senior Secured Notes - Additional Information (Detail) - Kronos Worldwide, Inc. - 3.75% Senior Secured Notes due 2025 € in Millions, $ in Millions	Sep. 30, 2024 EUR (€)	Sep. 30, 2024 USD ($)	Feb. 12, 2024 EUR (€)	Dec. 31, 2023
Debt Instrument [Line Items]
Debt instrument interest rate			3.75%
Debt instrument principal amount			€ 325
Kronos International, Inc
Debt Instrument [Line Items]
Debt instrument interest rate	3.75%	3.75%		3.75%
Debt instrument principal amount	€ 75
Principal amount outstanding | $		$ 83.9