v3.25.2
Document and Entity Information - shares
6 Months Ended
Jun. 30, 2025
Aug. 01, 2025
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2025  
Document Transition Report false  
Entity File Number 1-640  
Entity Registrant Name NL INDUSTRIES, INC.  
Entity Incorporation, State or Country Code NJ  
Entity Tax Identification Number 13-5267260  
Entity Address, Address Line One 5430 LBJ Freeway  
Entity Address, Address Line Two Suite 1700  
Entity Address, City or Town Dallas  
Entity Address, State or Province TX  
Entity Address, Postal Zip Code 75240-2620  
City Area Code 972  
Local Phone Number 233-1700  
Title of 12(b) Security Common stock  
Trading Symbol NL  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   48,862,734
Entity Central Index Key 0000072162  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Amendment Flag false