Equity Investment in Unconsolidated Subsidiary	12 Months Ended
Dec. 31, 2019
Equity Method Investments And Joint Ventures [Abstract]
Equity Investment in Unconsolidated Subsidiary	C. Equity Investment in Unconsolidated Subsidiary On November 6, 2019, the Company contributed $3.35 million to the Sponsor to fund the Sponsor’s purchase of $5.2 million of private warrants in a private placement that closed simultaneously with the consummation of the SPAC IPO. Each private warrant is exercisable to purchase one share of common stock of the SPAC at an exercise price of $11.50 per share, subject to adjustment. The Company contributed 62.2% of the Sponsor’s risk capital to effect the IPO, which corresponds to approximately a 43.57% membership interest in the Sponsor as of December 31, 2019. The Company is involved with a VIE through its investment in the Sponsor, which was determined to be a VIE. The Sponsor is managed by LGL Systems Nevada Management Partners LLC (“Nevada GP”), an affiliated entity deemed to be under the significant influence of Marc Gabelli, the Company’s Chairman of the Board. The Company has determined that it is not the primary beneficiary, as Nevada GP has the power to direct the activities of the Sponsor that most significantly impact the Sponsor’s economic performance through an operating agreement. The Company has determined that it has significant influence through Nevada GP as a result of Marc Gabelli, and will therefore account for the Sponsor under the equity method of accounting. The Sponsor has recorded losses of $26,000 during 2019, which are recognized by the Company in its statement of operations on its proportional equity investment. The Sponsor holds 20% of the shares in the SPAC along with 5,200,000 warrants at a strike price of $11.50. On November 7, 2019, the SPAC raised $172.5 million through the sale of 17.25 million shares and was listed as a publicly traded company on the NASDAQ Capital Market under the ticker symbol ‘DFNS’. The IPO closed on November 12, 2019. Prior to and immediately following the IPO, the Sponsor held 4,312,500 shares of the SPAC, which are restricted and non-tradable. If the SPAC does not complete a business combination within 24 months from the closing of the SPAC’s initial public offering, the proceeds from the sale of the private warrants will be used to fund the redemption of the shares sold in the SPAC’s initial public offering (subject to the requirements of applicable law), and the private warrants will expire worthless.

Equity Investment in Unconsolidated Subsidiary

12 Months Ended

Dec. 31, 2019

Equity Method Investments And Joint Ventures [Abstract]

Equity Investment in Unconsolidated Subsidiary

C. Equity Investment in Unconsolidated Subsidiary

On November 6, 2019, the Company contributed $3.35 million to the Sponsor to fund the Sponsor’s purchase of $5.2 million of private warrants in a private placement that closed simultaneously with the consummation of the SPAC IPO. Each private warrant is exercisable to purchase one share of common stock of the SPAC at an exercise price of $11.50 per share, subject to adjustment. The Company contributed 62.2% of the Sponsor’s risk capital to effect the IPO, which corresponds to approximately a 43.57% membership interest in the Sponsor as of December 31, 2019.

The Company is involved with a VIE through its investment in the Sponsor, which was determined to be a VIE. The Sponsor is managed by LGL Systems Nevada Management Partners LLC (“Nevada GP”), an affiliated entity deemed to be under the significant influence of Marc Gabelli, the Company’s Chairman of the Board. The Company has determined that it is not the primary beneficiary, as Nevada GP has the power to direct the activities of the Sponsor that most significantly impact the Sponsor’s economic performance through an operating agreement. The Company has determined that it has significant influence through Nevada GP as a result of Marc Gabelli, and will therefore account for the Sponsor under the equity method of accounting. The Sponsor has recorded losses of $26,000 during 2019, which are recognized by the Company in its statement of operations on its proportional equity investment.

The Sponsor holds 20% of the shares in the SPAC along with 5,200,000 warrants at a strike price of $11.50. On November 7, 2019, the SPAC raised $172.5 million through the sale of 17.25 million shares and was listed as a publicly traded company on the NASDAQ Capital Market under the ticker symbol ‘DFNS’. The IPO closed on November 12, 2019. Prior to and immediately following the IPO, the Sponsor held 4,312,500 shares of the SPAC, which are restricted and non-tradable.

If the SPAC does not complete a business combination within 24 months from the closing of the SPAC’s initial public offering, the proceeds from the sale of the private warrants will be used to fund the redemption of the shares sold in the SPAC’s initial public offering (subject to the requirements of applicable law), and the private warrants will expire worthless.