CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ (3.7)	$ 63.4
Other comprehensive income (loss), net of tax:
Currency translation	(6.1)	5.8
Other	(0.2)	(0.2)
Defined benefit pension plans	0.7	2.4
Total other comprehensive income, net	(5.6)	8.0
Comprehensive income	(9.3)	71.4
Comprehensive income attributable to noncontrolling interest	(0.3)	20.1
Comprehensive income attributable to Valhi stockholders	$ (9.0)	$ 51.3