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Reclassification of prior year balance to reflect current year presentation.

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Customer with revenues greater than 10%.

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The estimated forfeiture rate, based on past history of actual performance.

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The period of time the warranty is in effect.

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No definition available.

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For an unclassified balance sheet, the amount due from customers or clients for goods or services that have been delivered or sold in the normal course of business, reduced to their estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

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Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

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The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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No definition available.

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Amount representing an agreement for an unconditional promise by the maker to pay the entity (holder) a definite sum of money at a future date. Such amount may include accrued interest receivable in accordance with the terms of the note. The note also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among a myriad of other features and characteristics. Excludes amounts related to receivables held-for-sale.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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The value of all consideration given or received by the Entity in the significant acquisition or disposal.

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Accounting And Reporting Policies (Details) (USD $)	12 Months Ended
Accounting And Reporting Policies (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2011
Subsidiaries of the entity, by ownership percentage [Abstract]
Cash consideration	$ 700,000
Property, Plant and Equipment, Net [Abstract]
Depreciation expense	821,000us-gaap_Depreciation	913,000us-gaap_Depreciation
Standard Product Warranty Disclosure [Abstract]
Term of warranty	1 year
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2015	54,000
2016	54,000
2017	54,000
2018	54,000
2019	54,000
Thereafter	218,000
Total	488,000us-gaap_FiniteLivedIntangibleAssetsNet
Prior Year Reclassification [Abstract]
Prior Year Reclassification		76,000lgl_PriorYearReclassification
Intangible Assets [Abstract]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	488,000	36,000
Goodwill	40,000us-gaap_Goodwill	40,000us-gaap_Goodwill
Research and Development Costs [Abstract]
Research and development costs	2,166,000us-gaap_ResearchAndDevelopmentExpense	2,285,000us-gaap_ResearchAndDevelopmentExpense
Advertising Expense [Abstract]
Advertising costs	92,000us-gaap_AdvertisingExpense	90,000us-gaap_AdvertisingExpense
Stock-Based Compensation [Abstract]
Forfeiture rate (in hundredths)		5.00%
Earnings Per Share [Abstract]
Options excluded from the diluted earnings per share computation (in shares)	218,667	177,861
Foreign Currency Translation [Abstract]
Re-measurement loss	44,000	(86,000)
Restructuring Charges [Abstract]
Restructuring Charges	465,000us-gaap_RestructuringCharges	648,000us-gaap_RestructuringCharges
Revenues [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage (in hundredths)	11.00%	10.80%
Revenue concentration greater than 10%	2,522,000	2,840,000
Accounts Receivable [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage (in hundredths)	31.30%	27.60%
Accounts receivable	1,035,000	905,000
Number of large customers	3	3
Sale of Real Property Located in Bainbridge, Georgia [Member]
Significant Acquisitions and Disposals [Line Items]
Value of considerations received in sale			322,610
Principal amount of promissory note		$ 237,612	$ 322,610
Interest rate of promissory note (in hundredths)		3.25%	7.00%
Maturity date of promissory note		Jul. 28, 2016	Aug. 01, 2013
Minimum [Member]
Stock-Based Compensation [Abstract]
Forfeiture rate (in hundredths)	0.00%	0.00%
Minimum [Member] \| Buildings and Improvements [Member]
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment, Useful Life	5 years
Minimum [Member] \| Other Fixed Assets [Member]
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment, Useful Life	3 years
Maximum [Member]
Stock-Based Compensation [Abstract]
Forfeiture rate (in hundredths)	10.00%	5.00%
Maximum [Member] \| Buildings and Improvements [Member]
Property, Plant and Equipment, Net [Abstract]
Property, Plant and Equipment, Useful Life	35 years
Maximum [Member] \| Other Fixed Assets [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. (in hundredths)	100.00%
M-tron Industries, Ltd. [Member]
Subsidiaries of the entity, by ownership percentage [Abstract]
Owned by The LGL Group, Inc. (in hundredths)	99.90%
Piezo Technology, Inc. [Member]
Subsidiaries of the entity, by ownership percentage [Abstract]
Owned by The LGL Group, Inc. (in hundredths)	100.00%
Piezo Technology India Private Ltd. [Member]
Subsidiaries of the entity, by ownership percentage [Abstract]
Owned by The LGL Group, Inc. (in hundredths)	99.00%
M-tron Asia LLC [Member]
Subsidiaries of the entity, by ownership percentage [Abstract]
Owned by The LGL Group, Inc. (in hundredths)	100.00%
M-tron Services Ltd [Member]
Subsidiaries of the entity, by ownership percentage [Abstract]
Owned by The LGL Group, Inc. (in hundredths)	100.00%
Lynch Systems, Inc. [Member]
Subsidiaries of the entity, by ownership percentage [Abstract]
Owned by The LGL Group, Inc. (in hundredths)	100.00%