Parent Company (Franklin Financial Services Corporation) Financial Information (Schedule of Condensed Cash Flow Statement) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Condensed Financial Statements, Captions [Line Items]
Net income	$ 5,365	$ 6,569	$ 7,612
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized gains on sales and calls of securities	(44)	(157)	(673)
Net OTTI losses recognized in earnings	100	240	1,059
(Increase) decrease in other assets	(141)	(78)	963
Other, net	718	(135)	71
Net cash provided by operating activities	10,560	15,088	12,358
Proceeds from sales of investment securities	494	9,772	25,322
Net cash provided by investing activities	(4,510)	(33,558)	12,263
Dividends paid	(3,170)	(4,273)	(4,194)
Treasury stock issued under stock option plans	2	30	26
Common stock issued under dividend reinvestment plan	1,174	1,706	316
Net cash used in financing activities	37,640	30,508	(35,763)
(Decrease) increase in cash and cash equivalents	43,690	12,038	(11,142)
Cash and cash equivalents as of January 1	34,144	22,106	33,248
Cash and cash equivalents as of December 31	77,834	34,144	22,106
Corporation [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	5,365	6,569	7,612
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed income of subsidiaries	(3,142)	(3,843)	(4,069)
Net realized gains on sales and calls of securities	1	37	(8)
Net OTTI losses recognized in earnings		4	201
(Increase) decrease in other assets	(256)	(245)	(204)
(Decrease) increase in other liabilities	(12)	(238)
Other, net	(6)	103	13
Net cash provided by operating activities	1,950	2,387	3,545
Proceeds from sales of investment securities		81	21
Net cash provided by investing activities		81	21
Dividends paid	(3,170)	(4,273)	(4,194)
Treasury stock issued under stock option plans	2	30	26
Treasury shares issued to fund dividend reinvestment plan			617
Common stock issued under dividend reinvestment plan	1,174	1,706	316
Net cash used in financing activities	(1,994)	(2,537)	(3,235)
(Decrease) increase in cash and cash equivalents	(44)	(69)	331
Cash and cash equivalents as of January 1	419	488	157
Cash and cash equivalents as of December 31	$ 375	$ 419	$ 488