CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (2.2)	$ 42.4	$ (5.9)	$ 105.8
Other comprehensive income (loss), net of tax:
Currency translation	(4.9)	(32.6)	(11.0)	(26.8)
Defined benefit pension plans	5.6	2.3	6.3	4.7
Other	(0.2)	(0.1)	(0.4)	(0.3)
Total other comprehensive income (loss), net	0.5	(30.4)	(5.1)	(22.4)
Comprehensive income (loss)	(1.7)	12.0	(11.0)	83.4
Comprehensive income (loss) attributable to noncontrolling interest	2.6	6.4	2.3	26.5
Comprehensive income (loss) attributable to Valhi stockholders	$ (4.3)	$ 5.6	$ (13.3)	$ 56.9