Fair value measurements and financial instruments- Financial Instruments not Carried at Fair Value (Detail) € in Thousands, $ in Millions	Mar. 31, 2024 EUR (€)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Reported Value Measurement [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, cash equivalents and restricted cash equivalents		$ 399.6	$ 462.0
Estimate of Fair Value Measurement [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash, cash equivalents and restricted cash equivalents		399.6	462.0
Kronos Worldwide, Inc. | 9.50% Senior Secured Notes due March 15, 2029 | Kronos International, Inc
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long term debt, carrying amount	€ 276,174	292.3
Long term debt, fair value		318.5
Kronos Worldwide, Inc. | 3.75% Senior Secured Notes due September 15, 2025 | Kronos International, Inc
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long term debt, carrying amount		80.9	440.9
Long term debt, fair value		79.9	424.5
LandWell | Bank note payable
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Long term debt, carrying amount		12.2	12.2
Long term debt, fair value		$ 12.2	$ 12.2