Investment in Securities, Investment in Debt Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Investments in Debt Securities [Abstract]
Amortized cost	$ 2,998	$ 6,547
Gross unrealized holding gains	0	0
Gross unrealized holding losses	0	0
Estimated fair value	2,998	6,547
Foreign Government Obligations [Member]
Investments in Debt Securities [Abstract]
Amortized cost	2,998	6,547
Gross unrealized holding gains	0	0
Gross unrealized holding losses	0	0
Estimated fair value	$ 2,998	$ 6,547

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
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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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-Name Accounting Standards Codification
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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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-Publisher FASB
-Name Accounting Standards Codification
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