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Equity Investment in Unconsolidated Subsidiary - Additional Information (Details) - USD ($) |  |  | 9 Months Ended |
--- | --- | --- | --- | ---
Sep. 14, 2021 | Nov. 06, 2019 | Sep. 30, 2021 | Sep. 30, 2020 | Dec. 31, 2020
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |
Common stock, shares outstanding (in shares) |  |  | 5,280,204 |  | 5,272,204
Warrant |  |  | 2,065,000 |  |
LGL Systems Acquisition Holdings Company, LLC [Member] |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |
Contribution to fund purchase of private warrants |  | $ 6,100,000 |  |  |
IronNet [Member] |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |
Common stock, shares outstanding (in shares) | 1,572,529 |  |  |  |
Fair value | $ 65,300,000 |  |  |  |
Equity losses |  |  | $ 59,453,000 | $ (200,000) |
Cumulative loss on investments |  |  | $ 59,175,000 |  |
IronNet [Member] | Private Warrants [Member] |  |  |  |  |
Schedule Of Equity Method Investments [Line Items] |  |  |  |  |
Warrant | 2,065,000 |  |  |  |

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