Long-term debt - Senior Secured Notes - Additional Information (Detail)	6 Months Ended	12 Months Ended			3 Months Ended		9 Months Ended		12 Months Ended			9 Months Ended	12 Months Ended
	Jun. 30, 2012 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2012 Kronos Worldwide, Inc. [Member]	Mar. 31, 2011 6.5% Senior Secured Notes [Member] Kronos Worldwide, Inc. [Member] USD ($)	Mar. 31, 2011 6.5% Senior Secured Notes [Member] Kronos Worldwide, Inc. [Member] EUR (€)	Sep. 30, 2011 6.5% Senior Secured Notes [Member] Kronos Worldwide, Inc. [Member] USD ($)	Sep. 30, 2011 6.5% Senior Secured Notes [Member] Kronos Worldwide, Inc. [Member] EUR (€)	Dec. 31, 2011 6.5% Senior Secured Notes [Member] Kronos Worldwide, Inc. [Member] USD ($)	Dec. 31, 2011 6.5% Senior Secured Notes [Member] Kronos Worldwide, Inc. [Member] EUR (€)	Jun. 13, 2012 6.5% Senior Secured Notes [Member] Kronos Worldwide, Inc. [Member] EUR (€)	Sep. 30, 2011 6.5% Senior Secured Notes [Member] Kronos Worldwide, Inc. [Member] Aggregate Purchase Price [Member] EUR (€)	Dec. 31, 2011 6.5% Senior Secured Notes [Member] Kronos Worldwide, Inc. [Member] Aggregate Purchase Price [Member] EUR (€)
Debt Instrument [Line Items]
Principal amount of notes					$ 115,700,000	€ 80,000,000	$ 57,600,000	€ 40,600,000	$ 57,600,000	€ 40,600,000		€ 40,800,000	€ 40,800,000
Principal amount of debt instrument						400,000,000
Interest rate of Senior Secured Notes				6.50%	6.50%	6.50%
Term loan sufficient to pay principal, call premium		1.01083%			102.17%	102.17%
Call premium of senior long term notes		6,200,000	2,500,000		2,500,000
Principal amount outstanding											279,200,000
Net gain redemption of Senior Notes	7,200,000				3,300,000				200,000
Principal amount of notes										€ 40,800,000