Schedule of Investments (Parenthetical) - USD ($)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Collateral Amount On Open Futures Contracts	$ 101,001,407	$ 44,966,225
United States [Member] \| US Treasury Bill Securities 1.12%, 1/04/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.12%
Expiration date	1/04/2018
United States [Member] \| US Treasury Bill Securities 1.11%, 1/11/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.11%
Expiration date	1/11/2018
United States [Member] \| US Treasury Bill Securities 1.10%, 1/18/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.10%
Expiration date	1/18/2018
United States [Member] \| US Treasury Bill Securities 1.12%, 1/25/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.12%
Expiration date	1/25/2018
United States [Member] \| US Treasury Bill Securities 1.12%, 2/01/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.12%
Expiration date	2/01/2018
United States [Member] \| US Treasury Bill Securities 1.13%, 2/08/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.13%
Expiration date	2/08/2018
United States [Member] \| US Treasury Bill Securities 1.12%, 2/15/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.12%
Expiration date	2/15/2018
United States [Member] \| US Treasury Bill Securities 1.10%, 2/22/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.10%
Expiration date	2/22/2018
United States [Member] \| US Treasury Bill Securities 1.09%, 3/01/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.09%
Expiration date	3/01/2018
United States [Member] \| US Treasury Bill Securities 1.14%, 3/08/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.14%
Expiration date	3/08/2018
United States [Member] \| US Treasury Bill Securities 1.14%, 3/15/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.14%
Expiration date	3/15/2018
United States [Member] \| US Treasury Bill Securities 1.16%, 3/22/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.16%
Expiration date	3/22/2018
United States [Member] \| US Treasury Bill Securities 1.17%, 3/29/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.17%
Expiration date	3/29/2018
United States [Member] \| US Treasury Bill Securities 1.19%, 4/05/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.19%
Expiration date	4/05/2018
United States [Member] \| US Treasury Bill Securities 1.22%, 4/12/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.22%
Expiration date	4/12/2018
United States [Member] \| US Treasury Bill Securities 1.23%, 4/19/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.23%
Expiration date	4/19/2018
United States [Member] \| US Treasury Bill Securities 1.25%, 4/26/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.25%
Expiration date	4/26/2018
United States [Member] \| US Treasury Bill Securities 1.27%, 5/03/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.27%
Expiration date	5/03/2018
United States [Member] \| US Treasury Bill Securities 1.32%, 5/10/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.32%
Expiration date	5/10/2018
United States [Member] \| US Treasury Bill Securities 1.37%, 5/17/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.37%
Expiration date	5/17/2018
United States [Member] \| US Treasury Bill Securities 1.43%, 5/24/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.43%
Expiration date	5/24/2018
United States [Member] \| US Treasury Bill Securities 1.43%, 5/31/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.43%
Expiration date	5/31/2018
United States [Member] \| US Treasury Bill Securities 1.45%, 6/07/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.45%
Expiration date	6/07/2018
United States [Member] \| US Treasury Bill Securities 1.46%, 6/14/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.46%
Expiration date	6/14/2018
United States [Member] \| US Treasury Bill Securities 1.49%, 6/21/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.49%
Expiration date	6/21/2018
United States [Member] \| US Treasury Bill Securities 1.50%, 6/28/2018 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate	1.50%
Expiration date	6/28/2018
United States [Member] \| U.S. Treasury Bills Securities 0.34%, 1/05/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.34%
Expiration date		1/05/2017
United States [Member] \| U.S. Treasury Bills Securities 0.36%, 1/26/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.36%
Expiration date		1/26/2017
United States [Member] \| Us Treasury Bills Securities 0.40%, 2/02/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.40%
Expiration date		2/02/2017
United States [Member] \| Us Treasury Bills Securities 0.42%, 2/09/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.42%
Expiration date		2/09/2017
United States [Member] \| Us Treasury Bills Securities 0.45%, 2/16/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.45%
Expiration date		2/16/2017
United States [Member] \| Us Treasury Bills Securities 0.45%, 2/23/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.45%
Expiration date		2/23/2017
United States [Member] \| Us Treasury Bills Securities 0.45%, 3/02/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.45%
Expiration date		3/02/2017
United States [Member] \| Us Treasury Bills Securities 0.47%, 3/09/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.47%
Expiration date		3/09/2017
United States [Member] \| Us Treasury Bills Securities 0.50%, 3/16/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.50%
Expiration date		3/16/2017
United States [Member] \| Us Treasury Bills Securities 0.45%, 3/23/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.45%
Expiration date		3/23/2017
United States [Member] \| Us Treasury Bills Securities 0.43%, 3/30/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.43%
Expiration date		3/30/2017
United States [Member] \| Us Treasury Bills Securities 0.46%, 4/06/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.46%
Expiration date		4/06/2017
United States [Member] \| Us Treasury Bills Securities 0.47%, 4/13/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.47%
Expiration date		4/13/2017
United States [Member] \| Us Treasury Bills Securities 0.46%, 4/20/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.46%
Expiration date		4/20/2017
United States [Member] \| Us Treasury Bills Securities 0.47%, 4/27/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.47%
Expiration date		4/27/2017
United States [Member] \| Us Treasury Bills Securities 0.49%, 5/04/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.49%
Expiration date		5/04/2017
United States [Member] \| Us Treasury Bills Securities 0.55%, 5/11/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.55%
Expiration date		5/11/2017
United States [Member] \| Us Treasury Bills Securities 0.60%, 5/18/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.60%
Expiration date		5/18/2017
United States [Member] \| Us Treasury Bills Securities 0.61%, 5/25/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.61%
Expiration date		5/25/2017
United States [Member] \| Us Treasury Bills Securities 0.60%, 6/01/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.60%
Expiration date		6/01/2017
United States [Member] \| Us Treasury Bills Securities 0.62%, 6/08/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.62%
Expiration date		6/08/2017
United States [Member] \| Us Treasury Bills Securities 0.65%, 6/15/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.65%
Expiration date		6/15/2017
United States [Member] \| Us Treasury Bills Securities 0.64%, 6/22/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.64%
Expiration date		6/22/2017
United States [Member] \| Us Treasury Bills Securities 0.60%, 6/29/2017 [Member] \| US Treasury Securities [Member] \| Cash Equivalents [Member]
Interest rate		0.60%
Expiration date		6/29/2017