XML 11 R1.htm IDEA: XBRL DOCUMENT v3.25.3
Document and Entity Information - shares
 9 Months Ended
Sep. 30, 2025
Nov. 07, 2025
Document and Entity Information    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Sep. 30, 2025  
Document Transition Report false  
Securities Act File Number 001-40893  
Entity Registrant Name CATALYST BANCORP, INC.  
Entity Incorporation, State or Country Code LA  
Entity Tax Identification Number 86-2411762  
Entity Address, Address Line One 235 N. Court Street  
Entity Address, City or Town Opelousas  
Entity Address, State or Province LA  
Entity Address, Postal Zip Code 70570  
City Area Code 337  
Local Phone Number 948-3033  
Title of 12(b) Security Common Stock  
Trading Symbol CLST  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   4,113,660
Entity Central Index Key 0001849867  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q3  
Amendment Flag false