Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands		1 Months Ended		3 Months Ended					6 Months Ended			12 Months Ended
	Jun. 30, 2017	Jun. 30, 2018	Apr. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2017
Income Tax Disclosure [Line Items]
Dividends received from Kronos Worldwide, Inc.									$ 11,974		$ 10,566
U.S. federal corporate income tax rate				21.00%				35.00%	21.00%		35.00%	35.00%
Deferred income tax benefit from change in enacted tax rate												$ (37,500)
Current payable to affiliate		$ 461		$ 461		$ 429			$ 461	$ 429		429
Kronos
Income Tax Disclosure [Line Items]
Dividends received from Kronos Worldwide, Inc.									12,000		$ 10,600
Kronos | Expected Future Periods Net Operating Loss Utilization
Income Tax Disclosure [Line Items]
Increase (decrease) in non-cash deferred income tax asset valuation allowance	$ (149,900)
Kronos | Effect of Currency Exchange Rates
Income Tax Disclosure [Line Items]
Increase (decrease) in non-cash deferred income tax asset valuation allowance												13,700
Kronos | German | Expected Future Periods Net Operating Loss Utilization
Income Tax Disclosure [Line Items]
Increase (decrease) in non-cash deferred income tax asset valuation allowance	(141,900)
Kronos | German | Corporate Tax Purposes
Income Tax Disclosure [Line Items]
Net operating loss carryforwards						652,000				652,000		652,000
Kronos | German | Trade Tax Purposes
Income Tax Disclosure [Line Items]
Net operating loss carryforwards						500				500		500
Kronos | Belgium | Expected Future Periods Net Operating Loss Utilization
Income Tax Disclosure [Line Items]
Increase (decrease) in non-cash deferred income tax asset valuation allowance	$ (8,000)
Kronos | Belgium | Corporate Tax Purposes
Income Tax Disclosure [Line Items]
Net operating loss carryforwards						50,000				50,000		50,000
Kronos | Non-US
Income Tax Disclosure [Line Items]
Increase (decrease) in non-cash deferred income tax asset valuation allowance												$ (186,700)
Kronos | Non-US | Current Periods Net Operating Loss Utilization
Income Tax Disclosure [Line Items]
Increase (decrease) in non-cash deferred income tax asset valuation allowance								$ (7,700)		$ (24,100)	$ (12,700)
Kronos | European and Candadian Subsidiaries | Undistributed Earnings Previously Considered to be Permanently Reinvested
Income Tax Disclosure [Line Items]
Aggregate provisional non-cash deferred income tax expense (benefit)						4,500			$ 1,700
Kronos European Subsidiaries | Valhi
Income Tax Disclosure [Line Items]
Income tax liability payable period									8 years
Kronos European Subsidiaries | Valhi | Income Tax Payable
Income Tax Disclosure [Line Items]
Payable to affiliate		67,000		67,000					$ 67,000
Noncurrent payable to affiliate		64,000		64,000					64,000
Current payable to affiliate		3,000		$ 3,000					$ 3,000
Kronos European Subsidiaries | Transition Tax
Income Tax Disclosure [Line Items]
Currently payable (receivable)						$ 76,200
Current income tax expense payment period						8 years
Kronos European Subsidiaries | Transition Tax | 2017 Tax Year
Income Tax Disclosure [Line Items]
Current income tax expense payable in next fiscal year			$ 6,100
Kronos European Subsidiaries | Transition Tax | 2018 Tax Year
Income Tax Disclosure [Line Items]
Current income tax expense payable in next fiscal year		$ 3,100
Kronos Canadian Subsidiary | Earliest Tax Year | Canada-Germany APA | Canada Revenue Agency
Income Tax Disclosure [Line Items]
Effective tax year							2005
Kronos Canadian Subsidiary | Latest Tax Year | Canada-Germany APA | Canada Revenue Agency
Income Tax Disclosure [Line Items]
Effective tax year							2017
Kronos German Subsidiary | Earliest Tax Year | Germany- Canada APA | Germany Revenue Agency
Income Tax Disclosure [Line Items]
Effective tax year					2005
Kronos German Subsidiary | Latest Tax Year | Germany- Canada APA | Germany Revenue Agency
Income Tax Disclosure [Line Items]
Effective tax year					2017
Kronos Canadian And German Subsidiaries | Germany- Canada APA
Income Tax Disclosure [Line Items]
Non-cash income tax benefit					$ 1,400