Parent Company (Franklin Financial Services Corporation) Financial Information (Schedule Of Condensed 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]
Other									$ 246	$ 390	$ 109
Securities gains, net	$ 8	$ (10)	$ 2	$ (28)			$ 8	$ 718	22	8	280
Income before federal income tax expense	1,827	2,458	1,691	3,411	$ 2,760	$ 2,885	3,106	3,723	9,389	12,475	10,408
Federal income tax expense	104	383	130	685	493	306	632	839	1,302	2,271	2,006
Net income	$ 1,723	$ 2,075	$ 1,561	$ 2,726	$ 2,267	$ 2,579	$ 2,474	$ 2,884	8,087	10,204	8,402
Franklin Financial Service Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Dividends from Bank subsidiary									4,006	300	1,151
Interest and dividend income											15
Other										171
Securities gains, net											82
Income									4,006	471	1,248
Operating Expenses									972	986	795
Income before federal income tax expense									3,034	(515)	453
Federal income tax expense									(301)	(328)	(241)
Equity in undistributed income of subsidiary									4,752	10,391	7,708
Net income									$ 8,087	$ 10,204	$ 8,402