Capital Ratios (Schedule Of The Total Risk-based, Tier 1 Risk-based And Tier 1 Leverage Requirements) (Details)	Mar. 31, 2025	Dec. 31, 2024
Franklin Financial Services Corporation [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 Risk-based Capital Ratio: Ratio	0.1086	0.1131
Tier 1 Risk-based Capital Ratio: Ratio	0.1086	0.1131
Total Risk-based Capital Ratio: Ratio	0.1330	0.1385
Tier 1 Leverage Ratio: Ratio	0.0782	0.0792
Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 Risk-based Capital Ratio: Ratio	0.1144	0.1171
Common Equity Tier 1 Risk-based Capital Ratio: Adequately Capitalized Minimum: Ratio	0.0450
Common Equity Tier 1 Risk-based Capital Ratio: Well Capitalized Minimum: Ratio	0.065
Tier 1 Risk-based Capital Ratio: Ratio	0.1144	0.1171
Tier 1 Risk-based Capital Ratio: Adequately Capitalized Minimum: Ratio	0.0600
Tier 1 Risk-based Capital Ratio: Well Capitalized Minimum: Ratio	0.08
Total Risk-based Capital Ratio: Ratio	0.1269	0.1296
Total Risk-based Capital Ratio: Adequately Capitalized Minimum: Ratio	0.0800
Total Risk-based Capital Ratio: Well Capitalized Minimum: Ratio	0.10
Tier 1 Leverage Ratio: Ratio	0.0824	0.0820
Tier 1 Leverage Ratio: Adequately Capitalized Minimum: Ratio	0.0400
Tier 1 Leverage Ratio: Well Capitalized Minimum: Ratio	0.05

Tangible Capital Required For Well Capitalized To Tangible Assets

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Ratio of minimum total risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework.

+ References

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-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
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Ratio of minimum total risk-based capital to risk-weighted assets categorized as well capitalized as defined by regulatory framework for prompt corrective action.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Ratio of minimum tangible capital to tangible assets required for capital adequacy as defined by regulatory framework.

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