Investment in Securities, Investment in Debt Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Investments in Debt Securities [Abstract]
Amortized cost	$ 0	$ 64,988
Gross unrealized holding gains		6
Gross unrealized holding losses		0
Estimated fair value		64,994
U.S. Treasury Bills [Member]
Investments in Debt Securities [Abstract]
Amortized cost		64,988
Gross unrealized holding gains		6
Gross unrealized holding losses		0
Estimated fair value		$ 64,994

Amount, after allowance for credit loss, of investment in debt security measured at amortized cost (held-to-maturity).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
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-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27232-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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-Publisher FASB
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