Income Taxes - Additional Information (Detail) CAD in Millions		3 Months Ended			6 Months Ended	9 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2017 CAD	Sep. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)
Income Tax Disclosure [Line Items]
Dividends received from Kronos Worldwide, Inc.						$ 15,849,000	$ 15,849,000
Income tax benefit		$ (6,466,000)		$ 560,000		(28,923,000)	1,052,000
Kronos
Income Tax Disclosure [Line Items]
Dividends received from Kronos Worldwide, Inc.						15,800,000	$ 15,800,000
Deferred income tax asset valuation allowance									$ 0
Estimated reversal of deferred income tax asset valuation allowance		11,700,000				$ 11,700,000
Kronos | US-Canada APA
Income Tax Disclosure [Line Items]
U.S.-Canada Advance Pricing Agreement, description						During the third quarter of 2016, Contran, as the ultimate parent of Kronos’ U.S. Consolidated income tax group, executed and finalized an Advance Pricing Agreement with the U.S. Internal Revenue Service and Kronos’ Canadian subsidiary executed and finalized an Advance Pricing Agreement with the Competent Authority for Canada (collectively, the “U.S.-Canada APA”) effective for tax years 2005 - 2015.
Current U.S. income tax benefit				$ (5,600,000)
Kronos | US-Canada APA | Earliest Tax Year | Canada Revenue Agency
Income Tax Disclosure [Line Items]
Effective tax year				2005
Kronos | US-Canada APA | Latest Tax Year | Canada Revenue Agency
Income Tax Disclosure [Line Items]
Effective tax year				2015
Kronos | Expected Future Periods Net Operating Loss Utilization
Income Tax Disclosure [Line Items]
Increase (decrease) in non-cash deferred income tax asset valuation allowance	$ (149,900,000)
Kronos | Effect of Currency Exchange Rates
Income Tax Disclosure [Line Items]
Increase (decrease) in non-cash deferred income tax asset valuation allowance						$ 9,000,000
Kronos | Germany
Income Tax Disclosure [Line Items]
Deferred income tax asset valuation allowance								$ 153,000,000
Kronos | Germany | Expected Future Periods Net Operating Loss Utilization
Income Tax Disclosure [Line Items]
Increase (decrease) in non-cash deferred income tax asset valuation allowance	(141,900,000)
Kronos | Germany | Corporate Tax Purposes
Income Tax Disclosure [Line Items]
Net operating loss carryforwards								638,000,000
Kronos | Germany | Trade Tax Purposes
Income Tax Disclosure [Line Items]
Net operating loss carryforwards								71,000,000
Kronos | Belgium
Income Tax Disclosure [Line Items]
Deferred income tax asset valuation allowance								20,000,000
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	$ (8,000,000)
Kronos | Belgium | Corporate Tax Purposes
Income Tax Disclosure [Line Items]
Net operating loss carryforwards								93,000,000
Kronos | Germany and Belgian
Income Tax Disclosure [Line Items]
Deferred income tax asset valuation allowance								173,000,000
Increase (decrease) in non-cash deferred income tax asset valuation allowance						$ (170,400,000)
Kronos | Germany and Belgian | Current Periods Net Operating Loss Utilization
Income Tax Disclosure [Line Items]
Increase (decrease) in non-cash deferred income tax asset valuation allowance		(7,800,000)			$ (12,700,000)			$ (2,200,000)
Kronos Canadian Subsidiary | US-Canada APA
Income Tax Disclosure [Line Items]
Income tax paid		$ 2,300,000	CAD 3
Kronos Canadian Subsidiary | Canada-Germany APA | Earliest Tax Year | Canada Revenue Agency
Income Tax Disclosure [Line Items]
Effective tax year		2005	2005
Kronos Canadian Subsidiary | Canada-Germany APA | Latest Tax Year | Canada Revenue Agency
Income Tax Disclosure [Line Items]
Effective tax year		2017	2017
Kronos Canadian And German Subsidiaries | Canada-Germany APA | Canada Revenue Agency and German Federal Central Tax Office
Income Tax Disclosure [Line Items]
Income tax benefit		$ 11,300,000
Non-cash income tax benefit related to reversal of reserve for uncertain tax positions		8,100,000
Kronos Canadian And German Subsidiaries | Germany | Canada-Germany APA | Canada Revenue Agency and German Federal Central Tax Office
Income Tax Disclosure [Line Items]
Non-cash income tax benefit related to increase in German NOLs		2,600,000
Cash tax refund		$ 600,000