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Valhi Stockholders' Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
 12 Months Ended
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Mar. 31, 2021
Dec. 31, 2019
Schedule Of Stockholders Equity [Line Items]          
Common stock, par value $ 0.01 $ 0.01      
Treasury stock, shares 1,100,000 1,100,000 1,100,000    
Percentage of shares held by majority-owned subsidiary that has to be considered for voting purpose 100.00%        
Preferred stock, par value $ 0.01 $ 0.01      
Director Stock Plan          
Schedule Of Stockholders Equity [Line Items]          
Number of shares authorized       100,000 200,000
Shares awarded under plan 9,000 2,400      
Common stock available for future grant 84,600        
N L Industries Inc          
Schedule Of Stockholders Equity [Line Items]          
Treasury stock, shares 1,200,000 1,200,000      
Unrealized gain (loss) on sale of shares attributable to noncontrolling interest   $ 1.6 $ 3.3    
N L Industries Inc | Director Stock Plan          
Schedule Of Stockholders Equity [Line Items]          
Common stock available for future grant 200,000        
Kronos          
Schedule Of Stockholders Equity [Line Items]          
Shares available for purchase 1,017,518        
Treasury stock, shares 100,000 100,000      
Unrealized gain (loss) on sale of shares attributable to noncontrolling interest $ 1.7 $ 1.6 $ 3.3    
Kronos | Director Stock Plan          
Schedule Of Stockholders Equity [Line Items]          
Common stock available for future grant 97,100        
Comp X | Director Stock Plan          
Schedule Of Stockholders Equity [Line Items]          
Common stock available for future grant 124,450        
Common Stock          
Schedule Of Stockholders Equity [Line Items]          
Shares available for purchase 334,000       833,333