Schedule of Investments (Parenthetical) - USD ($)	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Collateral Amount On Open Futures Contracts	$ 433,776,173	$ 144,626,242
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.10%, 1/10/2019 [Member]
Interest rate	2.10%
Expiration date	1/10/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.13%, 1/17/2019 [Member]
Interest rate	2.13%
Expiration date	1/17/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.15%, 1/24/2019 [Member]
Interest rate	2.15%
Expiration date	1/24/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.18%, 1/31/2019 [Member]
Interest rate	2.18%
Expiration date	1/31/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.20%, 2/07/2019 [Member]
Interest rate	2.20%
Expiration date	2/07/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.19%, 2/14/2019 [Member]
Interest rate	2.19%
Expiration date	2/14/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.20%, 2/21/2019 [Member]
Interest rate	2.20%
Expiration date	2/21/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.24%, 2/28/2019 [Member]
Interest rate	2.24%
Expiration date	2/28/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.38%, 3/07/2019 [Member]
Interest rate	2.38%
Expiration date	3/07/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.28%, 3/14/2019 [Member]
Interest rate	2.28%
Expiration date	3/14/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.33%, 3/21/2019 [Member]
Interest rate	2.33%
Expiration date	3/21/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.34%, 3/28/2019 [Member]
Interest rate	2.34%
Expiration date	3/28/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.37%, 4/04/2019 [Member]
Interest rate	2.37%
Expiration date	4/04/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.41%, 4/11/2019 [Member]
Interest rate	2.41%
Expiration date	4/11/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.42%, 4/18/2019 [Member]
Interest rate	2.42%
Expiration date	4/18/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.43%, 4/25/2019 [Member]
Interest rate	2.43%
Expiration date	4/25/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.46%, 5/02/2019 [Member]
Interest rate	2.46%
Expiration date	5/02/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.47%, 5/09/2019 [Member]
Interest rate	2.47%
Expiration date	5/09/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.48%, 05/16/2019 [Member]
Interest rate	2.48%
Expiration date	5/16/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.50%, 5/23/2019 [Member
Interest rate	2.50%
Expiration date	5/23/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.49%, 5/30/2019 [Member]
Interest rate	2.49%
Expiration date	5/30/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.51%, 6/06/2019 [Member]
Interest rate	2.51%
Expiration date	6/06/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.51%, 6/13/2019 [Member]
Interest rate	2.51%
Expiration date	6/13/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.49%, 6/20/2019 [Member]
Interest rate	2.49%
Expiration date	6/20/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.49%, 6/27/2019 [Member]
Interest rate	2.49%
Expiration date	6/27/2019
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.12%, 1/04/2018 [Member]
Interest rate		1.12%
Expiration date		1/04/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.11%, 1/11/2018 [Member]
Interest rate		1.11%
Expiration date		1/11/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.10%, 1/18/2018 [Member]
Interest rate		1.10%
Expiration date		1/18/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.12%, 1/25/2018 [Member]
Interest rate		1.12%
Expiration date		1/25/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.12%, 2/01/2018 [Member]
Interest rate		1.12%
Expiration date		2/01/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.13%, 2/08/2018 [Member]
Interest rate		1.13%
Expiration date		2/08/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.12%, 2/15/2018 [Member]
Interest rate		1.12%
Expiration date		2/15/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.10%, 2/22/2018 [Member]
Interest rate		1.10%
Expiration date		2/22/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.09%, 3/01/2018 [Member]
Interest rate		1.09%
Expiration date		3/01/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.14%, 3/08/2018 [Member]
Interest rate		1.14%
Expiration date		3/08/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.14%, 3/15/2018 [Member]
Interest rate		1.14%
Expiration date		3/15/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.16%, 3/22/2018 [Member]
Interest rate		1.16%
Expiration date		3/22/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.17%, 3/29/2018 [Member]
Interest rate		1.17%
Expiration date		3/29/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.19%, 4/05/2018 [Member]
Interest rate		1.19%
Expiration date		4/05/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.22%, 4/12/2018 [Member]
Interest rate		1.22%
Expiration date		4/12/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 2.45%, 4/19/2018 [Member]
Interest rate		2.45%
Expiration date		4/19/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.25%, 4/26/2018 [Member]
Interest rate		1.25%
Expiration date		4/26/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.27%, 5/03/2018 [Member]
Interest rate		1.27%
Expiration date		5/03/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.32%, 5/10/2018 [Member]
Interest rate		1.32%
Expiration date		5/10/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.37%, 5/17/2018 [Member]
Interest rate		1.37%
Expiration date		5/17/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.43%, 5/24/2018 [Member]
Interest rate		1.43%
Expiration date		5/24/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.43%, 5/31/2018 [Member]
Interest rate		1.43%
Expiration date		5/31/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.45%, 6/07/2018 [Member]
Interest rate		1.45%
Expiration date		6/07/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.46%, 6/14/2018 [Member]
Interest rate		1.46%
Expiration date		6/14/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.49%, 6/21/2018 [Member]
Interest rate		1.49%
Expiration date		6/21/2018
Cash Equivalents [Member] \| United States [Member] \| United States Treasury Obligations [Member] \| U.S. Treasury Bills, 1.50%, 6/28/2018 [Member]
Interest rate		1.50%
Expiration date		6/28/2018