Consolidated Condensed Schedule of Investments (Cash Equivalents) - Cash equivalents shares in Thousands, $ in Thousands	Dec. 31, 2018 USD ($) shares
Schedule of Investments [Line Items]
Money Market Funds, at Carrying Value	$ 12,460
Investment Owned, Percent of Net Assets	2.09%
Money Market Funds, at Cost	$ 12,460
Various Money Market Funds [Member]
Schedule of Investments [Line Items]
Investment Owned, Balance, Shares \| shares	12,460
Money Market Funds, at Carrying Value	$ 12,460
Various Money Market Funds [Member] \| Minimum
Schedule of Investments [Line Items]
Investment Interest Rate	2.31%
Various Money Market Funds [Member] \| Maximum
Schedule of Investments [Line Items]
Investment Interest Rate	2.34%

Balance held at close of period in number of shares.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 210
-Section 50
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-URI http://asc.fasb.org/extlink&oid=99383244&loc=d3e12121-115841

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611133-123010

Name:	us-gaap_InvestmentOwnedBalanceShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant