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Condensed Schedule of Investments (Parenthetical)	9 Months Ended
	Sep. 30, 2017 USD ($)
Debt Instrument, Collateral Amount	$ 88,881,582
United States [Member] | US Treasury Bill Securities One [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.90%
Expiration date	10/05/2017
United States [Member] | US Treasury Bill Securities Two [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.92%
Expiration date	10/12/2017
United States [Member] | US Treasury Bill Securities Three [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.91%
Expiration date	10/19/2017
United States [Member] | US Treasury Bill Securities Four [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.95%
Expiration date	10/26/2017
United States [Member] | US Treasury Bill Securities Five [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.97%
Expiration date	11/02/2017
United States [Member] | US Treasury Bill Securities Six [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.01%
Expiration date	11/09/2017
United States [Member] | US Treasury Bill Securities Seven [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	0.98%
Expiration date	11/16/2017
United States [Member] | US Treasury Bill Securities Eight [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.05%
Expiration date	11/24/2017
United States [Member] | US Treasury Bill Securities Nine [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.05%
Expiration date	11/30/2017
United States [Member] | US Treasury Bill Securities Ten [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.08%
Expiration date	12/07/2017
United States [Member] | US Treasury Bill Securities Eleven [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.09%
Expiration date	12/14/2017
United States [Member] | US Treasury Bill Securities Twelve Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.11%
Expiration date	12/21/2017
United States [Member] | US Treasury Bill Securities Thirteen [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.10%
Expiration date	12/28/2017
United States [Member] | US Treasury Bill Securities Fourteen [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.12%
Expiration date	1/04/2018
United States [Member] | US Treasury Bill Securities Fifteen [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.11%
Expiration date	1/11/2018
United States [Member] | US Treasury Bill Securities Sixteen [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.10%
Expiration date	1/18/2018
United States [Member] | US Treasury Bill Securities Seventeen [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.12%
Expiration date	1/25/2018
United States [Member] | US Treasury Bill Securities Eighteen [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.12%
Expiration date	2/01/2018
United States [Member] | US Treasury Bill Securities Nineteen [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.13%
Expiration date	2/08/2018
United States [Member] | US Treasury Bill Securities Twenty [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.12%
Expiration date	2/15/2018
United States [Member] | US Treasury Bill Securities Twenty One [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.10%
Expiration date	2/22/2018
United States [Member] | US Treasury Bill Securities Twenty Two [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.09%
Expiration date	3/01/2018
United States [Member] | US Treasury Bill Securities Twenty Three [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.14%
Expiration date	3/08/2018
United States [Member] | US Treasury Bill Securities Twenty Four [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.14%
Expiration date	3/15/2018
United States [Member] | US Treasury Bill Securities Twenty Five [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.16%
Expiration date	3/22/2018
United States [Member] | US Treasury Bill Securities Twenty Six [Member] | US Treasury Securities [Member] | Cash Equivalents [Member]
Interest rate	1.17%
Expiration date	3/29/2018

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Amount of assets pledged to secure a debt instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 6
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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