Long-term debt - Kronos 9.50 Senior Secured Notes - Additional Information (Detail) $ in Millions					6 Months Ended
	Jul. 30, 2024 USD ($)	Feb. 14, 2024 USD ($)	Feb. 12, 2024 EUR (€)	Feb. 12, 2024 USD ($)	Jun. 30, 2024 USD ($)	Jul. 30, 2024 EUR (€)	Jun. 30, 2024 EUR (€)	Jun. 30, 2024 USD ($)	Feb. 14, 2024 EUR (€)	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
Remaining outstanding									€ 75,000,000
Kronos Worldwide, Inc. | Kronos International, Inc
Debt Instrument [Line Items]
Maximum amount of other indebtedness default before triggering customary default provisions | $				$ 50.0
Kronos Worldwide, Inc. | Kronos International, Inc | Direct Domestic Subsidiary of KII and Guarantors | Collateral Pledged
Debt Instrument [Line Items]
Parent company ownership interest			100.00%
Kronos Worldwide, Inc. | Kronos International, Inc | Foreign Subsidiary Directly Owned by KII or any Guarantor | Collateral Pledged
Debt Instrument [Line Items]
Parent company ownership interest			65.00%
Kronos Worldwide, Inc. | Kronos International, Inc | Foreign Subsidiary Directly Owned by KII or any Guarantor | Collateral Pledged | Non-voting Common Stock
Debt Instrument [Line Items]
Parent company ownership interest			100.00%
Kronos Worldwide, Inc. | 9.50% Senior Secured Notes due March 15, 2029 | Kronos International, Inc
Debt Instrument [Line Items]
Debt instrument interest rate			9.50%				9.50%	9.50%		9.50%
Principal amount			€ 325,000,000
Debt instrument principal amount			276,174,000
Cash consideration		$ 52.6	€ 48,750,000
Debt instrument, payment terms					bear interest at 9.50% per annum
Frequency of debt instrument payment					semi-annually
Debt Instrument, date of first required semi-annual payment			Sep. 15, 2024	Sep. 15, 2024
Debt instrument maturity date			Mar. 15, 2029	Mar. 15, 2029
Debt instrument, redemption, description					have a maturity date of March 15, 2029. Prior to March 15, 2026, Kronos may redeem some or all of the New Notes at a price equal to 100% of the principal amount thereof, plus an applicable premium as of the date of the redemption as described in the indenture governing its New Notes plus accrued and unpaid interest. On or after March 15, 2026, Kronos may redeem the New Notes at redemption prices ranging from 104.750% of the principal amount, declining to 100% on or after March 15, 2028, plus accrued and unpaid interest. In addition, on or before March 15, 2026, Kronos may redeem up to 40% of the New Notes with the net proceeds of certain public or private equity offerings at 109.50% of the principal amount, plus accrued and unpaid interest, provided that following the redemption at least 50% of the New Notes remain outstanding. If Kronos or Kronos’ subsidiaries experience certain change of control events, as outlined in the indenture governing its New Notes, Kronos would be required to make an offer to purchase the New Notes at 101% of the principal amount thereof, plus accrued and unpaid interest. Kronos would also be required to make an offer to purchase a specified portion of the New Notes at par value, plus accrued and unpaid interest, in the event that Kronos and its subsidiaries generate a certain amount of net proceeds from the sale of assets outside the ordinary course of business, and such net proceeds are not otherwise used for specified purposes within a specified time period as described in the indenture governing Kronos’ New Notes;
Debt Instrument Exchanged, Principal Amount of Each Instrument			€ 850
Debt Instrument Exchanged, Cash Paid For Each Instrument			€ 150
Long term debt, carrying amount							€ 276,174,000	$ 289.8
Unamortized debt issuance costs | $								5.5
Debt issuance costs, gross | $								$ 6.0
Kronos Worldwide, Inc. | 9.50% Senior Secured Notes due March 15, 2029 | Kronos International, Inc | Subsequent event
Debt Instrument [Line Items]
Debt instrument interest rate						9.50%
Debt instrument principal amount						€ 75,000,000
Premium percentage						107.50%
Net proceeds from issuance | $	$ 90.0
Kronos Worldwide, Inc. | 9.50% Senior Secured Notes due March 15, 2029 | Kronos International, Inc | Prior to March 15, 2026
Debt Instrument [Line Items]
Debt instrument, redemption price percentage			100.00%	100.00%
Kronos Worldwide, Inc. | 9.50% Senior Secured Notes due March 15, 2029 | Kronos International, Inc | On or After March 15, 2026
Debt Instrument [Line Items]
Debt instrument, redemption price percentage			104.75%	104.75%
Kronos Worldwide, Inc. | 9.50% Senior Secured Notes due March 15, 2029 | Kronos International, Inc | On or After March 15, 2028
Debt Instrument [Line Items]
Debt instrument, redemption price percentage			100.00%	100.00%
Kronos Worldwide, Inc. | 9.50% Senior Secured Notes due March 15, 2029 | Kronos International, Inc | On or Before March 15, 2026
Debt Instrument [Line Items]
Debt instrument, redemption price percentage			109.50%	109.50%
Debt instrument, percentage of debt that may be redeemed			40.00%	40.00%
Minimum redemption outstanding debt percentage			50.00%
Kronos Worldwide, Inc. | 9.50% Senior Secured Notes due March 15, 2029 | Kronos International, Inc | Certain Change Of control events
Debt Instrument [Line Items]
Debt instrument, redemption price percentage			101.00%	101.00%
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%
Long-Term Debt, Gross							€ 75,000,000
Debt instrument, par value			€ 1,000
Long term debt, carrying amount | $								$ 80.2		$ 440.9
Interest charge included in interest expense | $					$ 1.5