CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 2.9	$ 136.1	$ 197.7
Other comprehensive income (loss), net of tax:
Currency translation	3.6	(26.1)	(6.8)
Defined benefit pension plans	(5.9)	89.4	45.3
Other	(0.6)	1.0	(0.3)
Total other comprehensive income (loss), net	(2.9)	64.3	38.2
Comprehensive income		200.4	235.9
Comprehensive income attributable to noncontrolling interest	13.7	62.8	80.6
Comprehensive income (loss) attributable to Valhi stockholders	$ (13.7)	$ 137.6	$ 155.3