Quarterly report pursuant to Section 13 or 15(d)

Document and Entity Information

v3.21.4
Document and Entity Information - shares
 9 Months Ended
Sep. 30, 2021
Dec. 23, 2021
Document and Entity Information [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Transition Report false  
Document Period End Date Sep. 30, 2021  
Entity File Number 333-259483  
Entity Registrant Name NSTS Bancorp, Inc.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 87-2522769  
Entity Address, Address Line One 700 S. Lewis Ave.  
Entity Address, City or Town Waukegan  
Entity Address State Or Province IL  
Entity Address, Postal Zip Code 60085  
City Area Code 847  
Local Phone Number 336-4430  
Title of 12(b) Security Common Stock  
No Trading Symbol Flag true  
Entity Current Reporting Status No  
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   0
Entity Central Index Key 0001881592  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2021  
Document Fiscal Period Focus Q3  
Amendment Flag false