Parent Company (Franklin Financial Services Corporation) Condensed Financial Information (Statements Of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Condensed Financial Statements, Captions [Line Items]
Net income	$ 21,226	$ 11,099
Adjustments to reconcile net income to net cash provided by operating activities:
Stock based compensation	819	634
Deferred tax expense (benefit)	(751)	(473)
Net cash provided by operating activities	25,442	21,755
Dividends paid	(5,845)	(5,629)
Redemption of subordinate notes	(9,000)
Cash received from option exercises	286	122
Treasury stock purchase	(1,104)	(827)
Net cash provided by financing activities	5,687	343,084
(Decrease) increase in cash and cash equivalents	(75,892)	180,473
Cash and cash equivalents at the beginning of the period	203,613
Cash and cash equivalents at the end of the period	127,721	203,613
Franklin Financial Services Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	21,226	11,099
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed (income) of subsidiary	(16,608)	(7,341)
Stock based compensation	819	634
Change in fair value of equity security	7	(209)
Increase in other assets/liabilities	30	(531)
Net cash provided by operating activities	5,474	3,652
Dividends paid	(5,845)	(5,629)
Redemption of subordinate notes	(9,000)
Cash received from option exercises	286	122
Common stock issued under dividend reinvestment plan	1,225	1,749
Treasury stock purchase	(1,104)	(827)
Net cash provided by financing activities	(14,438)	(4,585)
(Decrease) increase in cash and cash equivalents	(8,964)	(933)
Cash and cash equivalents at the beginning of the period	9,137	10,070
Cash and cash equivalents at the end of the period	$ 173	$ 9,137