Schedule of Investments (Parenthetical) - USD ($)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Debt Instrument, Collateral Amount	$ 1,701,275	$ 699,804
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 1.12%, 1/04/2018 [Member]
Expiration date	1/04/2018
Interest Rate	1.12%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 1.11%, 1/11/2018 [Member]
Expiration date	1/11/2018
Interest Rate	1.11%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 1.10%, 1/18/2018 [Member]
Expiration date	1/18/2018
Interest Rate	1.10%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 1.12%, 01/25/2018 [Member]
Expiration date	1/25/2018
Interest Rate	1.12%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 1.12%, 2/01/2018 [Member]
Expiration date	2/01/2018
Interest Rate	1.12%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 1.13%, 2/08/2018 [Member]
Expiration date	2/08/2018
Interest Rate	1.13%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 1.12%, 2/15/2018 [Member]
Expiration date	2/15/2018
Interest Rate	1.12%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 1.10%, 2/22/2018 [Member]
Expiration date	2/22/2018
Interest Rate	1.10%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills:1.09%, 3/01/2018[Member]
Expiration date	3/01/2018
Interest Rate	1.09%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills:1.14%, 3/08/2018 [Member]
Expiration date	3/08/2018
Interest Rate	1.14%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 1.14%, 3/15/2018 [Member]
Expiration date	3/15/2018
Interest Rate	1.14%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills:1.16%,3/22/2018 [Member]
Expiration date	3/22/2018
Interest Rate	1.16%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 1.17%, 3/29/2018 [Member]
Expiration date	3/29/2018
Interest Rate	1.17%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills:1.19%, 4/05/2018 [Member]
Expiration date	4/05/2018
Interest Rate	1.19%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 1.22%, 4/12/2018 [Member]
Expiration date	4/12/2018
Interest Rate	1.22%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 1.23%,4/19/2018 [Member]
Expiration date	4/19/2018
Interest Rate	1.23%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills:1.25%, 4/26/2018[Member]
Expiration date	4/26/2018
Interest Rate	1.25%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 1.27%, 5/03/2018 [Member]
Expiration date	5/03/2018
Interest Rate	1.27%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills:1.32%, 5/10/2018 [Member]
Expiration date	5/10/2018
Interest Rate	1.32%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills:1.37%, 5/17/2018 [Member]
Expiration date	5/17/2018
Interest Rate	1.37%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills:1.43%, 5/24/2018 [Member]
Expiration date	5/24/2018
Interest Rate	1.43%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills:1.43%, 5/31/2018 [Member]
Expiration date	5/31/2018
Interest Rate	1.43%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills:1.45%, 6/07/2018[Member]
Expiration date	6/07/2018
Interest Rate	1.45%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills:1.46%, 6/14/2018 [Member]
Expiration date	6/14/2018
Interest Rate	1.46%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills:1.49%, 6/21/2018 [Member]
Expiration date	6/21/2018
Interest Rate	1.49%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills:1.50%,6/28/2018 [Member]
Expiration date	6/28/2018
Interest Rate	1.50%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 0.34%, 1/05/2017 [Member]
Expiration date		1/05/2017
Interest Rate		0.34%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 0.43%, 1/19/2017 [Member]
Expiration date		1/19/2017
Interest Rate		0.43%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills: 0.36%, 1/26/2017 [Member]
Expiration date		1/26/2017
Interest Rate		0.36%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.40%, 2/02/2017 [Member]
Expiration date		2/02/2017
Interest Rate		0.40%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.42%, 2/09/2017 [Member]
Expiration date		2/09/2017
Interest Rate		0.42%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.45%, 2/16/2017 [Member]
Expiration date		2/16/2017
Interest Rate		0.45%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.45%, 2/23/2017 [Member]
Expiration date		2/23/2017
Interest Rate		0.45%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.45%, 3/02/2017 [Member]
Expiration date		3/02/2017
Interest Rate		0.45%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.47%, 3/09/2017 [Member]
Expiration date		3/09/2017
Interest Rate		0.47%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.50%, 3/16/2017 [Member]
Expiration date		3/16/2017
Interest Rate		0.50%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.45%, 3/23/2017 [Member]
Expiration date		3/23/2017
Interest Rate		0.45%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.43%, 3/30/2017 [Member]
Expiration date		3/30/2017
Interest Rate		0.43%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.46%, 4/06/2017 [Member]
Expiration date		4/06/2017
Interest Rate		0.46%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.47%, 4/13/2017 [Member]
Expiration date		4/13/2017
Interest Rate		0.47%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.46%, 4/20/2017 [Member]
Expiration date		4/20/2017
Interest Rate		0.46%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.47%, 4/27/2017 [Member]
Expiration date		4/27/2017
Interest Rate		0.47%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.49%, 5/04/2017 [Member]
Expiration date		5/04/2017
Interest Rate		0.49%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.55%, 5/11/2017 [Member]
Expiration date		5/11/2017
Interest Rate		0.55%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.60%, 5/18/2017 [Member]
Expiration date		5/18/2017
Interest Rate		0.60%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.61%, 5/25/2017 [Member]
Expiration date		5/25/2017
Interest Rate		0.61%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.60%, 6/01/2017 [Member]
Expiration date		6/01/2017
Interest Rate		0.60%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.62%, 6/08/2017 [Member]
Expiration date		6/08/2017
Interest Rate		0.62%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.65%, 6/15/2017 [Member]
Expiration date		6/15/2017
Interest Rate		0.65%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.64%, 6/22/2017 [Member]
Expiration date		6/22/2017
Interest Rate		0.64%
Cash Equivalents [Member] \| Us Treasury Securities [Member] \| U.S. Treasury Bills : 0.60%, 6/29/2017 [Member]
Expiration date		6/29/2017
Interest Rate		0.60%

Amount of assets pledged to secure a debt instrument.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

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Balance Type:	debit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Balance Type:	na
Period Type:	instant

- Definition

The list of dates or date range within which the options may be exercised of the investment subject to option.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14.4(b))
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611322-123010

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 5
-Subparagraph (SX 210.12-13.5(d))
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611282-123010

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
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