Schedule of Investments	Dec. 31, 2017 USD ($) Contracts		Dec. 31, 2016 USD ($) Contracts
United States [Member] | Money Market Funds [Member]
Market Value	$ 2,500,000		$ 5,000,000
% of Partners' Capital	30.00%		30.40%
United States [Member] | Fidelity Investments Money Market Funds - Government Portfolio [Member] | Money Market Funds [Member]
Principal Amount	$ 1,000,000		$ 2,000,000
Market Value	$ 1,000,000		$ 2,000,000
% of Partners' Capital	12.00%		12.16%
United States [Member] | Goldman Sachs Financial Square Funds - Government Fund - Class FS [Member] | Money Market Funds [Member]
Principal Amount	$ 1,000,000		$ 1,000,000
Market Value	$ 1,000,000		$ 1,000,000
% of Partners' Capital	12.00%		6.08%
United States [Member] | Morgan Stanley Institutional Liquidity Funds - Government Portfolio [Member] | Money Market Funds [Member]
Principal Amount	$ 500,000		$ 2,000,000
Market Value	$ 500,000		$ 2,000,000
% of Partners' Capital	6.00%		12.16%
Cash Equivalents [Member] | United States Treasury Obligations [Member]
Market Value	$ 5,183,698		$ 6,292,035
% of Partners' Capital	62.19%		38.26%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.12%, 1/04/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 199,981
% of Partners' Capital	2.40%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.11%, 1/11/2018 [Member]
Principal Amount	$ 300,000
Market Value	$ 299,908
% of Partners' Capital	3.60%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.10%, 1/18/2018 [Member]
Principal Amount	$ 300,000
Market Value	$ 299,846
% of Partners' Capital	3.60%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.12%, 1/25/2018 [Member]
Principal Amount	$ 300,000
Market Value	$ 299,777
% of Partners' Capital	3.60%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.12%, 2/01/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 199,808
% of Partners' Capital	2.40%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.13%, 2/08/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 199,763
% of Partners' Capital	2.40%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.12%, 2/15/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 199,723
% of Partners' Capital	2.40%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.10%, 2/22/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 199,685
% of Partners' Capital	2.40%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.09%, 3/01/2018 [Member]
Principal Amount	$ 100,000
Market Value	$ 99,822
% of Partners' Capital	1.20%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.14%, 3/08/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 199,585
% of Partners' Capital	2.39%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.14%, 3/15/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 199,542
% of Partners' Capital	2.39%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.16%, 3/22/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 199,489
% of Partners' Capital	2.39%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.17%, 3/29/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 199,439
% of Partners' Capital	2.39%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.19%, 4/05/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 199,381
% of Partners' Capital	2.39%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.22%, 4/12/2018 [Member]
Principal Amount	$ 100,000
Market Value	$ 99,659
% of Partners' Capital	1.19%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.23%, 4/19/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 199,270
% of Partners' Capital	2.39%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.25%, 4/26/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 199,208
% of Partners' Capital	2.39%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.27%, 5/03/2018 [Member]
Principal Amount	$ 100,000
Market Value	$ 99,573
% of Partners' Capital	1.19%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.32%, 5/10/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 199,061
% of Partners' Capital	2.39%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.37%, 5/17/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 198,974
% of Partners' Capital	2.39%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.43%, 5/24/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 198,876
% of Partners' Capital	2.39%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.43%, 5/31/2018 [Member]
Principal Amount	$ 100,000
Market Value	$ 99,408
% of Partners' Capital	1.19%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.45%, 6/07/2018 [Member]
Principal Amount	$ 300,000
Market Value	$ 298,116
% of Partners' Capital	3.58%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.46%, 6/14/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 198,683
% of Partners' Capital	2.38%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.49%, 6/21/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 198,594
% of Partners' Capital	2.38%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 1.50%, 6/28/2018 [Member]
Principal Amount	$ 200,000
Market Value	$ 198,527
% of Partners' Capital	2.38%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills: 0.34%, 1/05/2017 [Member]
Principal Amount			$ 400,000
Market Value			$ 399,985
% of Partners' Capital			2.43%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills :0.43%, 1/19/2017 [Member]
Principal Amount			$ 500,000
Market Value			$ 499,894
% of Partners' Capital			3.04%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.36%, 1/26/2017 [Member]
Principal Amount			$ 500,000
Market Value			$ 499,875
% of Partners' Capital			3.04%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.40%, 2/02/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,929
% of Partners' Capital			1.22%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.42%, 2/09/2017 [Member]
Principal Amount			$ 300,000
Market Value			$ 299,864
% of Partners' Capital			1.82%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.45%, 2/16/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,885
% of Partners' Capital			1.22%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.45%, 2/23/2017 [Member]
Principal Amount			$ 300,000
Market Value			$ 299,803
% of Partners' Capital			1.82%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.45%, 3/02/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,850
% of Partners' Capital			1.22%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.47%, 3/09/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,825
% of Partners' Capital			1.22%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.50%, 3/16/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,793
% of Partners' Capital			1.22%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.45%, 3/23/2017 [Member]
Principal Amount			$ 300,000
Market Value			$ 299,700
% of Partners' Capital			1.82%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.43%, 3/30/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,790
% of Partners' Capital			1.22%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.46%, 4/06/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,760
% of Partners' Capital			1.22%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.47%, 4/13/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,734
% of Partners' Capital			1.22%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.46%, 4/20/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,725
% of Partners' Capital			1.21%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.47%, 4/27/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,700
% of Partners' Capital			1.21%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills :0.49%, 5/04/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,663
% of Partners' Capital			1.21%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.55%, 5/11/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,606
% of Partners' Capital			1.21%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.60%, 5/18/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,547
% of Partners' Capital			1.21%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.61%, 5/25/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,514
% of Partners' Capital			1.21%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.60%, 6/01/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,501
% of Partners' Capital			1.21%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.62%, 6/08/2017 [Member]
Principal Amount			$ 300,000
Market Value			$ 299,190
% of Partners' Capital			1.82%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.65%, 6/15/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,409
% of Partners' Capital			1.21%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.64%, 6/22/2017 [Member]
Principal Amount			$ 200,000
Market Value			$ 199,388
% of Partners' Capital			1.21%
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills : 0.60%, 6/29/2017 [Member]
Principal Amount			$ 300,000
Market Value			$ 299,105
% of Partners' Capital			1.82%
Cash Equivalents [Member] | United States [Member]
Market Value	$ 7,683,698		$ 11,292,035
% of Partners' Capital	92.19%		68.66%
Open Futures Contracts, Long [Member] | United States [Member]
Notional Amount	$ 8,907,842	[1]	$ 13,642,496	[2]
Number of Contracts | Contracts	292	[1]	454	[2]
Unrealized Gain (Loss) on Open Commodity Contracts	$ (568,922)	[1]	$ 2,796,004	[2]
% of Partners' Capital	(6.83%)	[1]	17.00%	[2]
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG February 2018 contracts, expiring January 2018 [Member]
Notional Amount	$ 872,763
Number of Contracts | Contracts	24
Unrealized Gain (Loss) on Open Commodity Contracts	$ (164,043)
% of Partners' Capital	(1.97%)
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG March 2018 contracts, expiring February 2018 [Member]
Notional Amount	$ 832,869
Number of Contracts | Contracts	24
Unrealized Gain (Loss) on Open Commodity Contracts	$ (135,429)
% of Partners' Capital	(1.63%)
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG April 2018 contracts, expiring March 2018 [Member]
Notional Amount	$ 715,113
Number of Contracts | Contracts	25
Unrealized Gain (Loss) on Open Commodity Contracts	$ (27,863)
% of Partners' Capital	(0.33%)
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG May 2018 contracts, expiring April 2018 [Member]
Notional Amount	$ 685,247
Number of Contracts | Contracts	24
Unrealized Gain (Loss) on Open Commodity Contracts	$ (27,407)
% of Partners' Capital	(0.33%)
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG June 2018 contracts, expiring May 2018 [Member]
Notional Amount	$ 731,645
Number of Contracts | Contracts	25
Unrealized Gain (Loss) on Open Commodity Contracts	$ (38,395)
% of Partners' Capital	(0.46%)
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG July 2018 contracts, expiring June 2018 [Member]
Notional Amount	$ 692,833
Number of Contracts | Contracts	24
Unrealized Gain (Loss) on Open Commodity Contracts	$ (19,873)
% of Partners' Capital	(0.24%)
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG August 2018 contracts, expiring July 2018 [Member]
Notional Amount	$ 722,063
Number of Contracts | Contracts	25
Unrealized Gain (Loss) on Open Commodity Contracts	$ (20,313)
% of Partners' Capital	(0.24%)
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG September 2018 contracts, expiring August 2018 [Member]
Notional Amount	$ 693,242
Number of Contracts | Contracts	24
Unrealized Gain (Loss) on Open Commodity Contracts	$ (23,882)
% of Partners' Capital	(0.29%)
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG October 2018 contracts, expiring September 2018 [Member]
Notional Amount	$ 712,475
Number of Contracts | Contracts	24
Unrealized Gain (Loss) on Open Commodity Contracts	$ (37,595)
% of Partners' Capital	(0.45%)
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG November 2018 contracts, expiring October 2018 [Member]
Notional Amount	$ 762,732
Number of Contracts | Contracts	25
Unrealized Gain (Loss) on Open Commodity Contracts	$ (45,982)
% of Partners' Capital	(0.55%)
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG December 2018 contracts, expiring November 2018 [Member]
Notional Amount	$ 762,850
Number of Contracts | Contracts	24
Unrealized Gain (Loss) on Open Commodity Contracts	$ (43,570)
% of Partners' Capital	(0.52%)
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG January 2019 contracts, expiring December 2018 [Member]
Notional Amount	$ 724,010
Number of Contracts | Contracts	24
Unrealized Gain (Loss) on Open Commodity Contracts	$ 15,430
% of Partners' Capital	0.18%
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG February 2017 contracts, expiring January 2017 [Member]
Notional Amount			$ 1,090,833
Number of Contracts | Contracts			38
Unrealized Gain (Loss) on Open Commodity Contracts			$ 324,287
% of Partners' Capital			1.97%
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG March 2017 contracts, expiring February 2017 [Member]
Notional Amount			$ 1,027,264
Number of Contracts | Contracts			38
Unrealized Gain (Loss) on Open Commodity Contracts			$ 372,656
% of Partners' Capital			2.27%
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG April 2017 contracts, expiring March 2017 [Member]
Notional Amount			$ 959,850
Number of Contracts | Contracts			37
Unrealized Gain (Loss) on Open Commodity Contracts			$ 359,570
% of Partners' Capital			2.19%
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG May 2017 contracts, expiring April 2017 [Member]
Notional Amount			$ 1,026,488
Number of Contracts | Contracts			38
Unrealized Gain (Loss) on Open Commodity Contracts			$ 319,852
% of Partners' Capital			1.94%
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG June 2017 contracts, expiring May 2017 [Member]
Notional Amount			$ 1,083,055
Number of Contracts | Contracts			38
Unrealized Gain (Loss) on Open Commodity Contracts			$ 269,745
% of Partners' Capital			1.64%
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG July 2017 contracts, expiring June 2017 [Member]
Notional Amount			$ 1,138,072
Number of Contracts | Contracts			38
Unrealized Gain (Loss) on Open Commodity Contracts			$ 224,608
% of Partners' Capital			1.37%
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG August 2017 contracts, expiring July 2017 [Member]
Notional Amount			$ 1,178,151
Number of Contracts | Contracts			38
Unrealized Gain (Loss) on Open Commodity Contracts			$ 180,349
% of Partners' Capital			1.10%
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG September 2017 contracts, expiring August 2017 [Member]
Notional Amount			$ 1,125,511
Number of Contracts | Contracts			38
Unrealized Gain (Loss) on Open Commodity Contracts			$ 224,249
% of Partners' Capital			1.36%
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG October 2017 contracts, expiring September 2017 [Member]
Notional Amount			$ 1,134,848
Number of Contracts | Contracts			37
Unrealized Gain (Loss) on Open Commodity Contracts			$ 186,052
% of Partners' Capital			1.13%
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG November 2017 contracts, expiring October 2017 [Member]
Notional Amount			$ 1,271,197
Number of Contracts | Contracts			38
Unrealized Gain (Loss) on Open Commodity Contracts			$ 98,323
% of Partners' Capital			0.60%
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG December 2017 contracts, expiring November 2017 [Member]
Notional Amount			$ 1,218,727
Number of Contracts | Contracts			38
Unrealized Gain (Loss) on Open Commodity Contracts			$ 188,413
% of Partners' Capital			1.14%
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG January 2018 contracts, expiring December 2017 [Member]
Notional Amount			$ 1,388,500
Number of Contracts | Contracts			38
Unrealized Gain (Loss) on Open Commodity Contracts			$ 47,900
% of Partners' Capital			0.29%

[1] Collateral amounted to $1,701,275 on open futures contracts.

[2] Collateral amounted to $699,804 on open futures contracts.