Related party transactions - Receivables from and Payables to Affiliates (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current receivables from affiliates:
Receivable from affiliates	$ 0.3	$ 29.6
Current payables to affiliates:
Payable to affiliates	52.8	21.4
Noncurrent note receivable from affiliate Valhi-Contran note receivable		11.2
Louisiana Pigment Company [Member]
Current receivables from affiliates:
Receivable from affiliates		29.6
Current payables to affiliates:
Payable to affiliates	23.4
Other [Member]
Current payables to affiliates:
Payable to affiliates		0.2
Contran [Member]
Current receivables from affiliates:
Receivable from affiliates	0.3
Current payables to affiliates:
Income taxes, net	2.6	0.1
Trade items	26.8	21.1
Contran [Member] | Credit Facility [Member]
Current payables to affiliates:
Note payable to affiliate included in long-term debt Valhi-Contran credit facility	157.6
Contran [Member] | Unsecured Revolving Demand Note Receivable [Member]
Current payables to affiliates:
Noncurrent note receivable from affiliate Valhi-Contran note receivable		$ 11.2