Business Segment Information - Segment Operating Performance (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Net sales	$ 556.3	$ 578.9	$ 1,819.9	$ 1,613.2
Cost of sales	435.9	426.2	1,382.1	1,226.6
Gross margin	120.4	152.7	437.8	386.6
Operating income (loss)	69.4	81.2	242.0	188.1
Interest income and other	3.3	0.9	5.6	2.9
Insurance recoveries	2.7		2.7
Gain on land and related sales		10.4		16.0
Changes in market value of Valhi common stock held by subsidiaries	(4.9)	(0.2)	(0.9)	2.0
Other components of net periodic pension and OPEB expense	(3.2)	(4.3)	(9.8)	(13.2)
General expenses, net	(8.6)	(8.7)	(27.3)	(26.1)
Interest expense	(7.0)	(7.9)	(20.9)	(25.2)
Income before income taxes	49.0	71.4	188.7	144.5
Chemicals
Segment Reporting Information [Line Items]
Net sales	459.6	499.8	1,587.8	1,443.4
Cost of sales	376.0	377.1	1,235.0	1,116.7
Gross margin	83.6	122.7	352.8	326.7
Operating income (loss)	34.3	60.3	189.9	145.4
Insurance recoveries	2.7
Component Products
Segment Reporting Information [Line Items]
Net sales	42.9	34.5	126.6	106.7
Cost of sales	30.9	23.6	88.9	73.4
Gross margin	12.0	10.9	37.7	33.3
Operating income (loss)	6.0	5.1	20.0	16.7
Real Estate Management And Development
Segment Reporting Information [Line Items]
Net sales	53.8	44.6	105.5	63.1
Cost of sales	29.0	25.5	58.2	36.5
Gross margin	24.8	19.1	47.3	26.6
Operating income (loss)	$ 29.1	$ 15.8	$ 32.1	$ 26.0