Parent Company (Franklin Financial Services Corporation) Financial Information (Schedule Of Condensed Comprehensive Income Statement) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Net income		$ 1,723	$ 2,075	$ 1,561	$ 2,726	$ 2,267	$ 2,579	$ 2,474	$ 2,884	$ 8,087	$ 10,204	$ 8,402
Securities:
Unrealized (losses) gains arising during the period	[1]									(1,176)	(498)	3,353
Reclassification adjustment for (gains) losses included in net income	[1]									18	(716)	(260)
Net unrealized (losses) gains	[1]									(1,158)	(1,214)	3,093
Tax effect	[1]									394	413	(1,052)
Net of tax amount	[1]									(764)	(801)	2,041
Total other comprehensive (loss) income of Parent										(493)	(622)	1,596
Franklin Financial Service Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Net income										8,087	10,204	8,402
Securities:
Unrealized (losses) gains arising during the period												(236)
Reclassification adjustment for (gains) losses included in net income												(82)
Net unrealized (losses) gains												(318)
Tax effect												108
Net of tax amount												(210)
Total other comprehensive (loss) income of Parent												(210)
Other comprehensive (loss) income of subsidiaries										(493)	(622)	1,806
Total Comprehensive Income										$ 7,594	$ 9,582	$ 9,998

[1] Securities / gain on conversion & securities (gains) losses, net ($6), $243, and $88 for years ended December 31, 2016, 2015, and 2014, respectively.