Fair Value of Financial Instruments (Levels) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments in securities:
Investments in trading securities	$ 50,324	$ 65,781
Total assets measured at fair value	54,562	65,781
Long Term Investment, at Cost, in Private Equity	3,400
Long Term Investment, at Cost, in a private investment fund	300
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net [Abstract]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	3,975	0	$ 0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	3,420	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Period Increase (Decrease)	555	0
Level 1
Investments in securities:
Investments in trading securities	50,324	65,781
Total assets measured at fair value	50,324	65,781
Level 2
Investments in securities:
Investments in trading securities	0	0
Total assets measured at fair value	0	0
Level 3
Investments in securities:
Investments in trading securities	0	0
Total assets measured at fair value	3,975	0
Long Term Investment, at Cost, in Private Equity	3,975
Inputs, Net Asset Value [Member]
Investments in securities:
Investments in trading securities	0	0
Total assets measured at fair value	263	$ 0
Long Term Investment, at Cost, in a private investment fund	$ 263

Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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-Paragraph 2
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Amount of increase (decrease) of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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-Topic 820
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-Section 50
-Paragraph 2
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Fair value of asset after deduction of liability.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.4)
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