Accounting and Reporting Policies - Subsidiaries of Company (Details)	12 Months Ended
	Dec. 31, 2019
LGL Systems Acquisition Holdings Company, LLC [Member]
Accounting And Reporting Policies [Line Items]
Owned by The LGL Group, Inc.	62.20%	[1]
M-tron Systems Holdings, LLC [Member]
Accounting And Reporting Policies [Line Items]
Owned by The LGL Group, Inc.	100.00%
M-tron Industries, Inc. [Member]
Accounting And Reporting Policies [Line Items]
Owned by The LGL Group, Inc.	100.00%
Piezo Technology, Inc. [Member]
Accounting And Reporting Policies [Line Items]
Owned by The LGL Group, Inc.	100.00%
Piezo Technology India Private Ltd. [Member]
Accounting And Reporting Policies [Line Items]
Owned by The LGL Group, Inc.	99.90%
M-tron Asia LLC [Member]
Accounting And Reporting Policies [Line Items]
Owned by The LGL Group, Inc.	100.00%
M-tron Industries, Ltd. [Member]
Accounting And Reporting Policies [Line Items]
Owned by The LGL Group, Inc.	100.00%
GC Opportunities Ltd. [Member]
Accounting And Reporting Policies [Line Items]
Owned by The LGL Group, Inc.	100.00%
M-tron Services Ltd [Member]
Accounting And Reporting Policies [Line Items]
Owned by The LGL Group, Inc.	100.00%
Precise Time and Frequency, LLC [Member]
Accounting And Reporting Policies [Line Items]
Owned by The LGL Group, Inc.	100.00%
Lynch Systems, Inc. [Member]
Accounting And Reporting Policies [Line Items]
Owned by The LGL Group, Inc.	100.00%

[1] Accounted for as an equity method investment