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Accounting And Reporting Policies (Details) $ in Thousands |  | 12 Months Ended
--- | --- | ---
Sep. 02, 2016 | Dec. 31, 2016 USD ($) Customer shares | Dec. 31, 2015 USD ($) Customer shares
Property, Plant and Equipment, Net [Abstract] |  |  |
Depreciation expense |  | $ 704 | $ 804
Standard Product Warranty Disclosure [Abstract] |  |  |
Term of warranty |  | 1 year |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |
Weighted average useful life of acquired intangible assets | 10 years |  |
Intangible Assets [Abstract] |  |  |
Intagible assets carrying value |  | $ 588 | 435
Goodwill |  | 40 | 40
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract] |  |  |
2017 |  | 75 |
2018 |  | 75 |
2019 |  | 75 |
2020 |  | 75 |
2021 |  | 75 |
Thereafter |  | 213 |
Total |  | 588 | 435
Research and Development Costs [Abstract] |  |  |
Research and development costs |  | 1,906 | 1,964
Advertising Expense [Abstract] |  |  |
Advertising costs |  | $ 50 | $ 146
Weighted Average Number of Shares Outstanding Reconciliation [Abstract] |  |  |
Weighted average shares outstanding - basic (in shares) | shares |  | 2,665,043 | 2,640,803
Effect of diluted securities | shares |  | 687 | 0
Weighted average shares outstanding - diluted (in shares) | shares |  | 2,665,730 | 2,640,803
Concentration Risk [Line Items] |  |  |
Revenue concentration greater than 10% |  | $ 20,891 | $ 20,713
Foreign Currency Translation [Abstract] |  |  |
Re-measurement loss |  | $ (2) | $ 35
Minimum [Member] |  |  |
Stock-Based Compensation [Abstract] |  |  |
Forfeiture rate |  | 0.00% | 0.00%
Maximum [Member] |  |  |
Intangible Assets [Abstract] |  |  |
Estimated useful life of intangible assets |  | 10 years |
Stock-Based Compensation [Abstract] |  |  |
Forfeiture rate |  | 25.00% | 10.00%
Buildings and Improvements [Member] | Minimum [Member] |  |  |
Property, Plant and Equipment, Net [Abstract] |  |  |
Property, Plant and Equipment, Useful Life |  | 5 years |
Buildings and Improvements [Member] | Maximum [Member] |  |  |
Property, Plant and Equipment, Net [Abstract] |  |  |
Property, Plant and Equipment, Useful Life |  | 35 years |
Other Fixed Assets [Member] | Minimum [Member] |  |  |
Property, Plant and Equipment, Net [Abstract] |  |  |
Property, Plant and Equipment, Useful Life |  | 3 years |
Other Fixed Assets [Member] | Maximum [Member] |  |  |
Property, Plant and Equipment, Net [Abstract] |  |  |
Property, Plant and Equipment, Useful Life |  | 10 years |
M-tron Industries, Inc. [Member] |  |  |
Subsidiaries of the entity, by ownership percentage [Abstract] |  |  |
Owned by The LGL Group, Inc. |  | 100.00% |
M-tron Industries, Ltd. [Member] |  |  |
Subsidiaries of the entity, by ownership percentage [Abstract] |  |  |
Owned by The LGL Group, Inc. |  | 100.00% |
Piezo Technology, Inc. [Member] |  |  |
Subsidiaries of the entity, by ownership percentage [Abstract] |  |  |
Owned by The LGL Group, Inc. |  | 100.00% |
Piezo Technology India Private Ltd. [Member] |  |  |
Subsidiaries of the entity, by ownership percentage [Abstract] |  |  |
Owned by The LGL Group, Inc. |  | 99.00% |
M-tron Asia LLC [Member] |  |  |
Subsidiaries of the entity, by ownership percentage [Abstract] |  |  |
Owned by The LGL Group, Inc. |  | 100.00% |
M-tron Services Ltd [Member] |  |  |
Subsidiaries of the entity, by ownership percentage [Abstract] |  |  |
Owned by The LGL Group, Inc. |  | 100.00% |
Lynch Systems, Inc. [Member] |  |  |
Subsidiaries of the entity, by ownership percentage [Abstract] |  |  |
Owned by The LGL Group, Inc. |  | 100.00% |
GC Opportunities Ltd. [Member] |  |  |
Subsidiaries of the entity, by ownership percentage [Abstract] |  |  |
Owned by The LGL Group, Inc. |  | 100.00% |
Precise Time and Frequenc, LLC [Member] |  |  |
Subsidiaries of the entity, by ownership percentage [Abstract] |  |  |
Owned by The LGL Group, Inc. |  | 100.00% |
Revenues [Member] | Customer Concentration Risk [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage |  | 15.70% | 12.70%
Revenue concentration greater than 10% |  | $ 3,275 | $ 2,627
Accounts Receivable [Member] | Customer Concentration Risk [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage |  | 35.10% | 31.40%
Accounts receivable |  | $ 1,242 | $ 819
Number of large customers | Customer |  | 4 | 3
Options [Member] |  |  |
Net Income (Loss) Per Share [Abstract] |  |  |
Securities excluded from the diluted earnings per share computation (in shares) | shares |  | 166,996 | 194,726
Warrant [Member] |  |  |
Net Income (Loss) Per Share [Abstract] |  |  |
Securities excluded from the diluted earnings per share computation (in shares) | shares |  | 519,241 | 519,241

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