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Schedule of Investments	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Fair Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ (14,454,899)	$ (20,768,690)
Money Market Funds [Member]
Market Value	$ 21,143,000
% of Partners' Capital	5.10%
Money Market Funds [Member] | Fidelity Investments Money Market Funds Government Portfolio [Member]
Shares/Principal Amount	$ 1,103,000
Market Value	$ 1,103,000
% of Partners' Capital	0.27%
Open Commodity Futures Contracts, Long [Member] | United States Contracts | NYMEX Natural Gas Futures NG February 2021 contracts, expiring January 2021 [Member]
Notional Amount	$ 429,022,819
Number of Contracts	16,328
Fair Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ (14,454,899)
% of Partners' Capital	(3.49%)
Open Futures Contracts - Long [Member] | United States Contracts | NYMEX Natural Gas Futures NG February 2019 contracts, expiring January 2019 [Member]
Notional Amount		$ 465,354,590
Number of Contracts		20,310
Fair Value/ Unrealized Gain (Loss) on Open Commodity Contracts		$ (20,768,690)
% of Partners' Capital		(4.67%)
Cash Equivalents [Member]
Market Value		$ 418,959,876
% of Partners' Capital		94.24%
Cash Equivalents [Member] | United States Treasury Obligations [Member]
Market Value		$ 258,959,876
% of Partners' Capital		58.25%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 2.05%, 1/02/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,999,438
% of Partners' Capital		2.25%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 2.03%, 1/09/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,995,533
% of Partners' Capital		2.25%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 2.01%, 1/16/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,991,729
% of Partners' Capital		2.25%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 2.04%, 1/23/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,987,674
% of Partners' Capital		2.25%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 2.02%, 1/30/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,983,905
% of Partners' Capital		2.25%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.90%, 2/06/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,981,225
% of Partners' Capital		2.25%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.87%, 2/13/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,977,843
% of Partners' Capital		2.24%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.85%, 2/20/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,974,514
% of Partners' Capital		2.24%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.85%, 2/27/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,971,025
% of Partners' Capital		2.24%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.83%, 3/05/2020 [Member]
Shares/Principal Amount		$ 20,000,000
Market Value		$ 19,935,413
% of Partners' Capital		4.48%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.84%, 3/19/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,960,567
% of Partners' Capital		2.24%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.88%, 3/26/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,956,083
% of Partners' Capital		2.24%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.70%, 4/02/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,956,811
% of Partners' Capital		2.24%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.64%, 4/09/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,955,175
% of Partners' Capital		2.24%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.60%, 4/16/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,953,183
% of Partners' Capital		2.24%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.60%, 4/23/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,950,092
% of Partners' Capital		2.24%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.59%, 4/30/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,947,500
% of Partners' Capital		2.24%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.54%, 5/07/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,946,201
% of Partners' Capital		2.24%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.55%, 5/14/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,942,678
% of Partners' Capital		2.24%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.55%, 5/21/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,939,879
% of Partners' Capital		2.24%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.58%, 5/28/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,935,456
% of Partners' Capital		2.23%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.53%, 6/04/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,934,556
% of Partners' Capital		2.23%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills, 1.53%, 6/11/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,931,488
% of Partners' Capital		2.23%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 1.54%, 6/18/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,928,175
% of Partners' Capital		2.23%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 1.57%, 6/25/2020 [Member]
Shares/Principal Amount		$ 10,000,000
Market Value		$ 9,923,733
% of Partners' Capital		2.23%
Cash Equivalents [Member] | United States Contracts | Money Market Funds [Member]
Market Value		$ 160,000,000
% of Partners' Capital		35.99%
Cash Equivalents [Member] | United States Contracts | Money Market Funds [Member] | Fidelity Investments Money Market Funds Government Portfolio [Member]
Shares/Principal Amount		$ 115,000,000
Market Value		$ 115,000,000
% of Partners' Capital		25.87%
Cash Equivalents [Member] | United States Contracts | Money Market Funds [Member] | Goldman Sachs Financial Square Funds - Government Fund - Class FS [Member]
Shares/Principal Amount		$ 25,000,000
Market Value		$ 25,000,000
% of Partners' Capital		5.62%
Cash Equivalents [Member] | United States Contracts | Money Market Funds [Member] | Morgan Stanley Institutional Liquidity Funds - Government Portfolio [Member]
Shares/Principal Amount		$ 20,000,000
Market Value		$ 20,000,000
% of Partners' Capital		4.50%
Cash Equivalents [Member] | United States Contracts | Money Market Funds [Member] | RBC U.S. Government Money Market Fund - Institutional Share Class [Member]
Shares/Principal Amount	$ 20,040,000
Market Value	$ 20,040,000
% of Partners' Capital	4.83%

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