Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Investments in securities [Abstract]
Estimated Fair Value	$ 17,819	$ 27,726
Common Stocks [Member]
Investments in securities [Abstract]
Estimated Fair Value	16,729	26,463
Open-end Funds [Member]
Investments in securities [Abstract]
Estimated Fair Value	661	752
Closed-end Funds [Member]
Investments in securities [Abstract]
Estimated Fair Value	429	511
Recurring Basis [Member]
Assets [Abstract]
Cash equivalents	77,481	85,823
Investments in securities [Abstract]
Estimated Fair Value	17,819	27,726
Total assets at fair value	95,300	113,549
Recurring Basis [Member] \| Common Stocks [Member]
Investments in securities [Abstract]
Estimated Fair Value	16,729	26,463
Recurring Basis [Member] \| Open-end Funds [Member]
Investments in securities [Abstract]
Estimated Fair Value	661	752
Recurring Basis [Member] \| Closed-end Funds [Member]
Investments in securities [Abstract]
Estimated Fair Value	429	511
Recurring Basis [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Cash equivalents	77,481	85,823
Investments in securities [Abstract]
Estimated Fair Value	17,819	27,726
Total assets at fair value	95,300	113,549
Recurring Basis [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| Common Stocks [Member]
Investments in securities [Abstract]
Estimated Fair Value	16,729	26,463
Recurring Basis [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| Open-end Funds [Member]
Investments in securities [Abstract]
Estimated Fair Value	661	752
Recurring Basis [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| Closed-end Funds [Member]
Investments in securities [Abstract]
Estimated Fair Value	429	511
Recurring Basis [Member] \| Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Cash equivalents	0	0
Investments in securities [Abstract]
Estimated Fair Value	0	0
Total assets at fair value	0	0
Recurring Basis [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Common Stocks [Member]
Investments in securities [Abstract]
Estimated Fair Value	0	0
Recurring Basis [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Open-end Funds [Member]
Investments in securities [Abstract]
Estimated Fair Value	0	0
Recurring Basis [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Closed-end Funds [Member]
Investments in securities [Abstract]
Estimated Fair Value	0	0
Recurring Basis [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Cash equivalents	0	0
Investments in securities [Abstract]
Estimated Fair Value	0	0
Total assets at fair value	0	0
Recurring Basis [Member] \| Significant Unobservable Inputs (Level 3) [Member] \| Common Stocks [Member]
Investments in securities [Abstract]
Estimated Fair Value	0	0
Recurring Basis [Member] \| Significant Unobservable Inputs (Level 3) [Member] \| Open-end Funds [Member]
Investments in securities [Abstract]
Estimated Fair Value	0	0
Recurring Basis [Member] \| Significant Unobservable Inputs (Level 3) [Member] \| Closed-end Funds [Member]
Investments in securities [Abstract]
Estimated Fair Value	$ 0	$ 0

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
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- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=99377092&loc=SL75136599-209740

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