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