Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2023	Feb. 29, 2024	Jun. 30, 2023
Document And Entity Information [Abstract]
Document Type	10-K/A
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-38884
Entity Registrant Name	FRANKLIN FINANCIAL SERVICES CORPORATION
Entity Incorporation, State or Country Code	PA
Entity Tax Identification Number	25-1440803
Entity Address, Address Line One	1500 Nitterhouse Drive
Entity Address, City or Town	Chambersburg
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	17201-0819
City Area Code	717
Local Phone Number	264-6116
Title of 12(b) Security	Common stock
Trading Symbol	FRAF
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	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
ICFR Auditor Attestation	false
Entity Public Float			$ 108,078,178
Entity Common Stock, Shares Outstanding		4,383,720
Documents Incorporated by Reference	Portions of the definitive annual proxy statement to be filed, pursuant to Reg. 14A within 120 days after December 31, 2023, are incorporated into Part III.
Entity Central Index Key	0000723646
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	true
Amendment Description	Franklin Financial Services Corporation is filing this Annual Report on Form 10-K/A (this “Amendment”) to correct the Form 10-K for the year ended December 31, 2023 filed on March 11, 2024 (the “Original Filing”). The Amendment is being filed to include the Total Performance Graph in Item 5 – Market for Registrant’s Common Equity, Related Shareholder Matters and Issuer Purchases of Equity Securities. In addition, pursuant to Rule 12b-15 under the Securities Exchange Act of 1934, as amended, this Amendment includes new certifications of our principal executive officer and principal financial officer on Exhibits 31.1, 31.2 and 32.1 and 32.2, each as of the date of filing this Amendment. Except as described above, this Amendment does not modify or update disclosures presented in the Original Form 10-K to reflect events occurring after the filing of the Original Form 10-K. Accordingly, this Amendment should be read in conjunction with the Original Form 10-K and the Company’s filings with the U.S. Securities and Exchange Commission subsequent to the filing of the Original Form 10-K.
Error Correction Flag	false
Auditor Name	Crowe LLP
Auditor Firm ID	173
Auditor Location	Cleveland, Ohio