v3.25.2
Cover - 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  
Entity File Number 0-26589  
Entity Registrant Name FIRST BANCORP, INC  
Entity Incorporation, State or Country Code ME  
Entity Tax Identification Number 01-0404322  
Entity Address, Address Line One 223 Main Street  
Entity Address, City or Town Damariscotta  
Entity Address, State or Province ME  
Entity Address, Postal Zip Code 04543  
City Area Code 207  
Local Phone Number 563-3195  
Title of 12(b) Security Common Stock, par value $0.01 per share  
Trading Symbol FNLC  
Security Exchange Name NASDAQ  
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   11,210,588
Entity Central Index Key 0000765207  
Current Fiscal Year End Date --12-31  
Transition Report false  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Amendment Flag false