Parent Company (Franklin Financial Services Corporation) Condensed Financial Information (Statements Of Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Condensed Financial Statements, Captions [Line Items]
Change in fair value of equity securities	$ (7)	$ 209
Interest expense	44,725	43,937
Income before income taxes	26,267	13,315
Income tax benefit	(5,041)	(2,216)
Net income	21,226	11,099
Total other comprehensive gain (loss)	13,919	5,432
Total Comprehensive Income (Loss)	35,145	16,531
Franklin Financial Services Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Dividends from Bank subsidiary	7,350	5,956
Change in fair value of equity securities	(7)	209
Dividends		7
Income	7,343	6,172
Interest expense	1,281	1,050
Operating expenses	2,261	1,932
Income before income taxes	3,801	3,190
Income tax benefit	817	568
Equity in undistributed income of subsidiaries	16,608	7,341
Net income	21,226	11,099
Total other comprehensive gain (loss)	13,919	5,432
Total Comprehensive Income (Loss)	$ 35,145	$ 16,531