Income Taxes - Additional Information (Detail) CAD in Millions, $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2017 USD ($)	Mar. 31, 2016	Dec. 31, 2016 USD ($)	Mar. 31, 2017 CAD
Income Taxes Disclosure [Line Items]
U.S. federal statutory income tax rate	35.00%	35.00%
Income tax examination, description	Tax authorities are examining certain of our U.S. and non-U.S. tax returns and have or may propose tax deficiencies, including penalties and interest. Because of the inherent uncertainties involved in settlement initiatives and court and tax proceedings, we cannot guarantee that these matters will be resolved in our favor, and therefore our potential exposure, if any, is also uncertain. We believe we have adequate accruals for additional taxes and related interest expense which could ultimately result from tax examinations. We believe the ultimate disposition of tax examinations should not have a material adverse effect on our consolidated financial position, results of operations or liquidity. As a result of ongoing audits in certain jurisdictions, in 2008 Kronos filed Advance Pricing Agreement Requests with the tax authorities in the U.S., Canada and Germany. These requests have been under review with the respective tax authorities since 2008 and prior to 2016, it was uncertain whether an agreement would be reached between the tax authorities and whether we would agree to execute and finalize such agreements. During 2016, Contran, as the ultimate parent of our U.S. Consolidated income tax group, executed and finalized an Advance Pricing Agreement with the U.S. Internal Revenue Service and our 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.
Income taxes	$ 9.6		$ 5.1
Increase (decrease) in unrecognized tax benefits	(14.4)
Kronos Worldwide, Inc. | Germany and Belgium
Income Taxes Disclosure [Line Items]
Deferred income tax benefit	5.0
Kronos Worldwide, Inc. | Earliest Tax Year | US-Canada APA
Income Taxes Disclosure [Line Items]
Effective tax year			2005
Kronos Worldwide, Inc. | Latest Tax Year | US-Canada APA
Income Taxes Disclosure [Line Items]
Effective tax year			2015
Kronos Canadian Subsidiary | US-Canada APA
Income Taxes Disclosure [Line Items]
Income taxes	$ 2.3			CAD 3