CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Cash flows from operating activities:
Net income (loss)	$ (1.9)	$ 40.8	$ (7.8)	$ 146.6
Depreciation and amortization			40.7	44.3
Gain from sale of land	0.0	0.0	(1.5)	0.0
Loss on pension plan termination	0.0	0.0	6.2	0.0
Benefit plan expense greater (less) than cash funding			(5.7)	4.5
Deferred income taxes			(37.4)	5.1
Contributions to TiO2 manufacturing joint venture, net			(2.8)	(8.5)
Fixed asset impairment	0.0	0.4	0.0	16.4
Loss on deconsolidation of BWC	0.0	2.0	0.0	2.0
Other, net			4.6	10.2
Change in assets and liabilities:
Accounts and other receivables, net			(60.9)	(23.6)
Inventories, net			103.3	(142.0)
Land held for development, net			0.2	17.8
Accounts payable and accrued liabilities			(78.4)	20.1
Income taxes			1.6	(2.5)
Accounts with affiliates			(5.8)	5.0
Other, net			(17.5)	(67.5)
Net cash provided by (used in) operating activities			(61.2)	27.9
Cash flows from investing activities:
Capital expenditures			(42.7)	(48.0)
Purchases of marketable securities			(63.7)	(3.5)
Proceeds from disposal of marketable securities			56.5	2.4
Proceeds from land sales			1.8	0.0
Cash, cash equivalents and restricted cash of BWC			0.0	(8.6)
Other, net			0.0	0.1
Net cash used in investing activities			(48.1)	(57.6)
Cash flows from financing activities:
Principal payments on indebtedness			(24.5)	(47.5)
Valhi cash dividends paid			(6.8)	(6.7)
Distributions to noncontrolling interest in subsidiaries			(19.0)	(27.5)
Subsidiary treasury stock acquired			(2.9)	(2.8)
Net cash used in financing activities			(53.2)	(84.5)
Cash, cash equivalents and restricted cash and cash equivalents - net change from:
Operating, investing and financing activities			(162.5)	(114.2)
Effect of exchange rates on cash			(2.8)	(15.6)
Balance at beginning of period			562.0	792.9	$ 792.9
Balance at end of period	$ 396.7	$ 663.1	396.7	663.1	$ 562.0
Cash paid for:
Interest, net of amounts capitalized			24.0	22.9
Income taxes, net			24.5	37.3
Noncash investing activities:
Change in accruals for capital expenditures			$ 0.7	$ 2.0