Financial Instruments - Additional Information (Detail)					12 Months Ended
	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2014 Amalgamated Sugar Company LLC USD ($)	Dec. 31, 2014 Kronos Worldwide, Inc. 2014 Term Loan Per Thousand Dollar Principal Amount USD ($)	Dec. 31, 2014 Kronos Worldwide, Inc. Forward Contracts USD ($)	Dec. 31, 2013 Kronos Worldwide, Inc. Forward Contracts USD ($)	Dec. 31, 2014 Kronos Worldwide, Inc. Norwegian Kroner Forward Contracts USD ($)	Dec. 31, 2014 Kronos Worldwide, Inc. Norwegian Kroner Forward Contracts Euro EUR (€)	Dec. 31, 2014 Kronos Worldwide, Inc. Minimum Norwegian Kroner Forward Contracts USD ($)	Dec. 31, 2014 Kronos Worldwide, Inc. Minimum Norwegian Kroner Forward Contracts Euro EUR (€)	Dec. 31, 2014 Kronos Worldwide, Inc. Maximum Norwegian Kroner Forward Contracts USD ($)	Dec. 31, 2014 Kronos Worldwide, Inc. Maximum Norwegian Kroner Forward Contracts Euro EUR (€)
Financial Instrument At Fair Value [Line Items]
Notional amount currency forward contract							$ 37,000,000	€ 31,700,000
Exchange floor rate									6.75	8.52	7.11	8.81
Maturity rate of derivative									2,700,000	1,100,000	5,000,000	5,000,000
Estimated fair value of currency forward contracts	(4,200,000)	(1,000,000)			4,200,000	1,000,000
Estimated fair value of currency forward contracts included accounts and other receivables						200,000
Estimated fair value of currency forward contracts included accounts payable and accrued liabilities					4,200,000	1,200,000
Currency transaction loss					(4,200,000)	(1,000,000)
Estimated market price of the notes				983.1
Principal amount of debt instrument				1,000
Marketable securities	$ 255,600,000	$ 253,300,000	$ 250,000,000