Note 4 - Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2023		Sep. 30, 2023		Jun. 30, 2023		Mar. 31, 2023		Dec. 31, 2022		Sep. 30, 2022		Jun. 30, 2022		Mar. 31, 2022		Dec. 31, 2023	Dec. 31, 2022
Revenues:
Net sales	$ 446		$ 438		$ 403		$ 441		$ 524		$ 344		$ 370		$ 417		$ 1,728	$ 1,655
Net investment income	549		544		275		198		352		54		10		(3)		1,566	413
Net gains (losses)	0	[1]	(4)	[1]	43	[1]	345	[1]	(298)	[1]	(2,121)	[1]	(2,373)	[1]	45	[1]	384	(4,747)
Total revenues	995		978		721		984		578		(1,723)		(1,993)		459		3,678	(2,679)
Expenses:
Manufacturing cost of sales	201		195		208		192		165		203		227		242		796	837
Engineering, selling and administrative	465		584		645		542		576		669		623		1,022		2,236	2,890
Total expenses	666		779		853		734		741		872		850		1,264		3,032	3,727
Income (loss) from continuing operations before income taxes																	646	(6,406)
Income tax expense (benefit)	169		69		(2)		65		(164)		(611)		(588)		(166)		301	(1,529)
Income (loss) from continuing operations	160		130		(130)		185		1	[2]	(1,984)	[2]	(2,255)	[2]	(639)	[2]	345	(4,877)
(Loss) income from discontinued operations, net of tax	0		0		0		(28)		132		488		457		808		(28)	1,885
Net loss attributable to LGL Group or non-controlling interests	160		130		(130)		157		133		(1,496)		(1,798)		169		317	(2,992)
Less: Net income attributable to non-controlling interests	26		22		0		0		0		0		0		0		48	0
Net income (loss) attributable to LGL Group common stockholders	$ 134		$ 108		$ (130)		$ 157		$ 133		$ (1,496)		$ (1,798)		$ 169		269	(2,992)
Operating Segments [Member] | Electronic Instruments [Member]
Revenues:
Net sales																	1,728	1,655
Net investment income																	0	0
Net gains (losses)																	0	0
Total revenues																	1,728	1,655
Expenses:
Manufacturing cost of sales																	796	837
Engineering, selling and administrative																	780	715
Total expenses																	1,576	1,552
Income (loss) from continuing operations before income taxes																	152	103
Income tax expense (benefit)																	0	0
Income (loss) from continuing operations																	152	103
(Loss) income from discontinued operations, net of tax																	0	0
Net loss attributable to LGL Group or non-controlling interests																	152	103
Less: Net income attributable to non-controlling interests																	0	0
Net income (loss) attributable to LGL Group common stockholders																	152	103
Operating Segments [Member] | Merchant Investment [Member]
Revenues:
Net sales																	0	0
Net investment income																	869	0
Net gains (losses)																	0	0
Total revenues																	869	0
Expenses:
Manufacturing cost of sales																	0	0
Engineering, selling and administrative																	216	0
Total expenses																	216	0
Income (loss) from continuing operations before income taxes																	653	0
Income tax expense (benefit)																	0	0
Income (loss) from continuing operations																	653	0
(Loss) income from discontinued operations, net of tax																	0	0
Net loss attributable to LGL Group or non-controlling interests																	653	0
Less: Net income attributable to non-controlling interests																	48	0
Net income (loss) attributable to LGL Group common stockholders																	605	0
Corporate, Non-Segment [Member]
Revenues:
Net sales																	0	0
Net investment income																	697	413
Net gains (losses)																	384	(4,747)
Total revenues																	1,081	(4,334)
Expenses:
Manufacturing cost of sales																	0	0
Engineering, selling and administrative																	1,240	2,175
Total expenses																	1,240	2,175
Income (loss) from continuing operations before income taxes																	(159)	(6,509)
Income tax expense (benefit)																	301	(1,529)
Income (loss) from continuing operations																	(460)	(4,980)
(Loss) income from discontinued operations, net of tax																	(28)	1,885
Net loss attributable to LGL Group or non-controlling interests																	(488)	(3,095)
Less: Net income attributable to non-controlling interests																	0	0
Net income (loss) attributable to LGL Group common stockholders																	$ (488)	$ (3,095)

[1] During Q1 and Q2 2023, the net gains primarily relate to the sale of our investments in mutual funds managed by GAMCO Investors, Inc.

[2] Basic and diluted earnings per share are calculated using actual, unrounded amounts. Therefore, (i) the components of earnings per share may not sum to its corresponding total or (ii) the quarterly earnings per share may not sum to the earnings per share on the Consolidated Statements of Operations.