Organization and Basis of Presentation - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2020
Valhi Inc | Kronos Worldwide, Inc.
Organization And Basis Of Presentation [Line Items]
Ownership percentage in subsidiary	50.00%
Valhi Inc | NL Industries Inc.
Organization And Basis Of Presentation [Line Items]
Ownership percentage in company	83.00%
NL Industries Inc. | Kronos Worldwide, Inc.
Organization And Basis Of Presentation [Line Items]
Ownership percentage	30.00%
Contran
Organization And Basis Of Presentation [Line Items]
Controlling interest description	Consequently, at March 31, 2020, Ms. Simmons, Ms. Connelly and the Family Trust may be deemed to control Contran, and therefore may be deemed to indirectly control the wholly-owned subsidiary of Contran, Valhi, NL and us
Contran | Valhi Inc
Organization And Basis Of Presentation [Line Items]
Ownership percentage of parent company held by related party	92.00%