v3.25.1
Document And Entity Information - shares
3 Months Ended
Mar. 31, 2025
Apr. 30, 2025
Document Information [Line Items]    
Entity Central Index Key 0000740663  
Entity Registrant Name FIRST OF LONG ISLAND CORP  
Amendment Flag false  
Current Fiscal Year End Date --12-31  
Document Fiscal Period Focus Q1  
Document Fiscal Year Focus 2025  
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2025  
Document Transition Report false  
Entity File Number 001-32964  
Entity Incorporation, State or Country Code NY  
Entity Tax Identification Number 11-2672906  
Entity Address, Address Line One 275 Broadhollow Road  
Entity Address, City or Town Melville  
Entity Address, State or Province NY  
Entity Address, Postal Zip Code 11747  
City Area Code 516  
Local Phone Number 671-4900  
Title of 12(b) Security Common stock, $0.10 par value per share  
Trading Symbol FLIC  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Accelerated Filer  
Entity Emerging Growth Company false  
Entity Small Business false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   22,679,517