Cover - USD ($)	12 Months Ended
Dec. 31, 2025	Mar. 01, 2026	Jun. 30, 2025
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2025
Current Fiscal Year End Date	--12-31
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 Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction	false
Entity Shell Company	false
Entity Public Float			$ 271,239,386
Entity Common Stock, Shares Outstanding		11,270,319
Documents Incorporated by Reference	Proxy Statement for the Annual Meeting of Shareholders to be held on April 29, 2026
Entity Central Index Key	0000765207
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
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