Organization and basis of presentation - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Jun. 30, 2023
Revision of Prior Period, Reclassification, Adjustment [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Gross, Period Increase (Decrease)	$ 19.1
Revision of Prior Period, Reclassification, Adjustment [Member] | Land [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Gross, Period Increase (Decrease)	(5.3)
Revision of Prior Period, Reclassification, Adjustment [Member] | Equipment [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Gross, Period Increase (Decrease)	(45.8)
Revision of Prior Period, Reclassification, Adjustment [Member] | Building [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Gross, Period Increase (Decrease)	5.1
Revision of Prior Period, Reclassification, Adjustment [Member] | Mining properties
Basis Of Presentation And Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Gross, Period Increase (Decrease)	$ 65.1
Contran | Valhi Incorporation
Basis Of Presentation And Significant Accounting Policies [Line Items]
Parent company ownership interest		91.00%