Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2023	Oct. 27, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
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	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		48,833,484
Entity Central Index Key	0000072162
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false