Long-Term Debt - Kronos Term Loans - Additional Information (Detail)		1 Months Ended	3 Months Ended	6 Months Ended	8 Months Ended	12 Months Ended
	Sep. 13, 2017 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Sep. 13, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 13, 2017 EUR (€)
Debt Instrument [Line Items]
Loss on prepayment of debt			$ 7,100,000				$ 7,100,000
Kronos Worldwide, Inc. | North American Revolving Credit Facility
Debt Instrument [Line Items]
Repayments of debt	$ 21,000,000
Kronos Worldwide, Inc. | Notes Payable, Other Payables | 2014 Term Loan
Debt Instrument [Line Items]
Repayments of debt		$ 338,600,000
Quarterly principal payment				$ 1,800,000				$ 1,800,000
Debt instrument, voluntary repayment period						2017-09
Loss on prepayment of debt			7,100,000
Write-off of unamortized debt issuance costs			2,700,000
Write-off of unamortized original issue discount			700,000
Termination of interest rate swap contract			$ 3,300,000
Debt instrument, average interest rate during period					4.10%
Kronos Worldwide, Inc. | Kronos International, Inc | 3.75% Senior Secured Notes due September 15, 2025
Debt Instrument [Line Items]
Debt instrument principal amount	$ 477,600,000				$ 477,600,000				€ 400,000,000
Debt instrument maturity date	Sep. 15, 2025
Debt instrument interest rate	3.75%				3.75%				3.75%
Debt instrument, interest payment terms						bear interest at 3.75% per annum, payable semi-annually on March 15 and September 15 of each year, beginning on March 15, 2018
Debt instrument, frequency of periodic payment of interest						semi-annually
Debt Instrument, date of first required semi-annual payment	Mar. 15, 2018
Debt instrument redemption price percent if experiences certain specified change of control events	101.00%
Debt instrument, redemption, description						have a maturity date of September 15, 2025. Prior to September 15, 2020, Kronos may redeem some or all of the Senior Notes at a price equal to 100% of the principal amount thereof, plus a “make-whole” premium (as defined in the indenture governing the Senior Notes). On or after September 15, 2020, Kronos may redeem the Senior Notes at redemption prices ranging from 102.813% of the principal amount, declining to 100% on or after September 15, 2023. In addition, on or before September 15, 2020, Kronos may redeem up to 40% of the Senior Notes with the net proceeds of certain public or private equity offerings at 103.75% of the principal amount. If Kronos experiences certain specified change of control events, it would be required to make an offer to purchase the Senior Notes at 101% of the principal amount. Kronos would also be required to make an offer to purchase a specified portion of the Senior Notes at par value in the event that it generates 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;
Maximum amount of other indebtedness default before triggering customary default provisions	$ 50,000,000
Unamortized debt issuance costs						$ 6,300,000	$ 7,500,000
Kronos Worldwide, Inc. | Kronos International, Inc | 3.75% Senior Secured Notes due September 15, 2025 | Collateral Pledged | Direct Domestic Subsidiary of KII and Guarantors
Debt Instrument [Line Items]
Parent company ownership interest	100.00%				100.00%				100.00%
Kronos Worldwide, Inc. | Kronos International, Inc | 3.75% Senior Secured Notes due September 15, 2025 | Collateral Pledged | Foreign Subsidiary Directly Owned by KII or any Guarantor
Debt Instrument [Line Items]
Parent company ownership interest	65.00%				65.00%				65.00%
Kronos Worldwide, Inc. | Kronos International, Inc | 3.75% Senior Secured Notes due September 15, 2025 | Non-voting Common Stock | Collateral Pledged | Foreign Subsidiary Directly Owned by KII or any Guarantor
Debt Instrument [Line Items]
Parent company ownership interest	100.00%				100.00%				100.00%
Kronos Worldwide, Inc. | Kronos International, Inc | 3.75% Senior Secured Notes due September 15, 2025 | Prior to September 15, 2020
Debt Instrument [Line Items]
Debt instrument, redemption price percentage	100.00%
Kronos Worldwide, Inc. | Kronos International, Inc | 3.75% Senior Secured Notes due September 15, 2025 | On or After September 15, 2020
Debt Instrument [Line Items]
Debt instrument, redemption price percentage	102.813%
Kronos Worldwide, Inc. | Kronos International, Inc | 3.75% Senior Secured Notes due September 15, 2025 | On or After September 15, 2023
Debt Instrument [Line Items]
Debt instrument, redemption price percentage	100.00%
Kronos Worldwide, Inc. | Kronos International, Inc | 3.75% Senior Secured Notes due September 15, 2025 | On or Before September 15, 2020
Debt Instrument [Line Items]
Debt instrument, redemption price percentage	103.75%
Kronos Worldwide, Inc. | Kronos International, Inc | 3.75% Senior Secured Notes due September 15, 2025 | On or Before September 15, 2020 | Maximum
Debt Instrument [Line Items]
Debt instrument, percentage of debt that may be redeemed	40.00%