Schedule of Investments [Parenthetical] - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Collateral amount on open futures contracts	$ 17,417,768	$ 14,167,416
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.10%, 1/03/2019
Interest rate	2.10%
Expiration date	1/03/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.10%, 1/10/2019
Interest rate	2.10%
Expiration date	1/10/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.13%, 1/17/2019
Interest rate	2.13%
Expiration date	1/17/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.15%, 1/24/2019
Interest rate	2.15%
Expiration date	1/24/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.18%, 1/31/2019
Interest rate	2.18%
Expiration date	1/31/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.20%, 2/07/2019
Interest rate	2.20%
Expiration date	2/07/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.19%, 2/14/2019
Interest rate	2.19%
Expiration date	2/14/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.20%, 2/21/2019
Interest rate	2.20%
Expiration date	2/21/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.24%, 2/28/2019
Interest rate	2.24%
Expiration date	2/28/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.38%, 3/07/2019
Interest rate	2.38%
Expiration date	3/07/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.28%, 3/14/2019
Interest rate	2.28%
Expiration date	3/14/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.33%, 3/21/2019
Interest rate	2.33%
Expiration date	3/21/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.34%, 3/28/2019
Interest rate	2.34%
Expiration date	3/28/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.37%, 4/04/2019
Interest rate	2.37%
Expiration date	4/04/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.41%, 4/11/2019
Interest rate	2.41%
Expiration date	4/11/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.42%, 4/18/2019
Interest rate	2.42%
Expiration date	4/18/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.43%, 4/25/2019
Interest rate	2.43%
Expiration date	4/25/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.46%, 5/02/2019
Interest rate	2.46%
Expiration date	5/02/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.47%, 5/09/2019
Interest rate	2.47%
Expiration date	5/09/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.48%, 5/16/2019
Interest rate	2.48%
Expiration date	5/16/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.50%, 5/23/2019
Interest rate	2.50%
Expiration date	5/23/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.49%, 5/30/2019
Interest rate	2.49%
Expiration date	5/30/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.51%, 6/06/2019
Interest rate	2.51%
Expiration date	6/06/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.51%, 6/13/2019
Interest rate	2.51%
Expiration date	6/13/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.49%, 6/20/2019
Interest rate	2.49%
Expiration date	6/20/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,2.49%, 6/27/2019
Interest rate	2.49%
Expiration date	6/27/2019
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.12%, 1/04/2018
Interest rate		1.12%
Expiration date		1/04/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.11%, 1/11/2018
Interest rate		1.11%
Expiration date		1/11/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.10%, 1/18/2018
Interest rate		1.10%
Expiration date		1/18/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.12%, 1/25/2018
Interest rate		1.12%
Expiration date		1/25/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.12%, 2/01/2018
Interest rate		1.12%
Expiration date		2/01/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.13%, 2/08/2018
Interest rate		1.13%
Expiration date		2/08/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.12%, 2/15/2018
Interest rate		1.12%
Expiration date		2/15/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.10%, 2/22/2018
Interest rate		1.10%
Expiration date		2/22/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.09%, 3/01/2018
Interest rate		1.09%
Expiration date		3/01/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.14%, 3/08/2018
Interest rate		1.14%
Expiration date		3/08/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.14%, 3/15/2018
Interest rate		1.14%
Expiration date		3/15/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.16%, 3/22/2018
Interest rate		1.16%
Expiration date		3/22/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.17%, 3/29/2018
Interest rate		1.17%
Expiration date		3/29/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.19%, 4/05/2018
Interest rate		1.19%
Expiration date		4/05/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.22%, 4/12/2018
Interest rate		1.22%
Expiration date		4/12/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.23%, 4/19/2018
Interest rate		1.23%
Expiration date		4/19/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.25%, 4/26/2018
Interest rate		1.25%
Expiration date		4/26/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.27%, 5/03/2018
Interest rate		1.27%
Expiration date		5/03/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.32%, 5/10/2018
Interest rate		1.32%
Expiration date		5/10/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.37%, 5/17/2018
Interest rate		1.37%
Expiration date		5/17/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.43%, 5/24/2018
Interest rate		1.43%
Expiration date		5/24/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.43%, 5/31/2018
Interest rate		1.43%
Expiration date		5/31/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.45%, 6/07/2018
Interest rate		1.45%
Expiration date		6/07/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.46%, 6/14/2018
Interest rate		1.46%
Expiration date		6/14/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.49%, 6/21/2018
Interest rate		1.49%
Expiration date		6/21/2018
Cash Equivalents [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills,1.50%, 6/28/2018
Interest rate		1.50%
Expiration date		6/28/2018

Amount of assets pledged to secure a debt instrument.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (d)
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- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
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- 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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 5
-Subparagraph (SX 210.12-13.5(d))
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-SubTopic 320
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14.4(b))
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611322-123010

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