Investments (Details 2) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt securities, held-to-maturity	$ 49,098
Mutual funds (available for sale) [Member]
Debt securities, held-to-maturity	609	$ 599
Gross Unrealized Fair Value	591	563
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(18)	(36)
Money Market Funds [Member]
Debt securities, held-to-maturity	3,695	4,822
Gross Unrealized Fair Value	3,695	4,822
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Commercial Paper [Member]
Debt securities, held-to-maturity	9,054	6,178
Gross Unrealized Fair Value	9,054	6,178
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Bonds [Member]
Debt securities, held-to-maturity	49,098	55,720
Gross Unrealized Fair Value	49,376	56,181
Gross Unrealized Gains	306	505
Gross Unrealized Losses	(28)	(44)
Equity investments [Member]
Debt securities, held-to-maturity	5,675	5,675
Gross Unrealized Fair Value	4,103	4,077
Gross Unrealized Gains	0	0
Gross Unrealized Losses	$ (1,572)	$ (1,598)

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

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

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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
-Paragraph 5
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-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27232-111563

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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