Schedule of Investments (Unaudited) - Futures Contracts - Futures [Member]		6 Months Ended	12 Months Ended
		Jun. 30, 2017 USD ($) Contract	Dec. 31, 2016 USD ($) Contract
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(5.60%)	3.95%
Unrealized Appreciation/ (Depreciation)	[1]	$ (100,033,905)	$ 101,032,417
Notional Value		$ 1,786,213,835	$ 2,557,065,161
CME SWAPS MARKETS (CBOT) [Member] | Corn [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.16%	0.05%
Unrealized Appreciation/ (Depreciation)	[1]	$ 2,901,846	$ 1,268,361
Notional Value		$ 101,669,850	$ 129,584,812
Number of Contracts | Contract		5,337	6,981
Maturity Date		Sep. 14, 2017	Sep. 14, 2017
CME SWAPS MARKETS (CBOT) [Member] | Soybean [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(0.08%)	0.12%
Unrealized Appreciation/ (Depreciation)	[1]	$ (1,471,443)	$ 3,209,119
Notional Value		$ 98,339,250	$ 133,400,362
Number of Contracts | Contract		2,060	2,697
Maturity Date		Nov. 14, 2017	Nov. 14, 2017
CME SWAPS MARKETS (CBOT) [Member] | Wheat [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.62%	(1.14%)
Unrealized Appreciation/ (Depreciation)	[1]	$ 11,130,486	$ (29,220,100)
Notional Value		$ 108,033,862	$ 125,563,388
Number of Contracts | Contract		3,789	5,783
Maturity Date		Jul. 13, 2018	Jul. 14, 2017
CME SWAPS MARKETS (COMEX) [Member] | Gold [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(0.58%)	(1.12%)
Unrealized Appreciation/ (Depreciation)	[1]	$ (10,268,565)	$ (28,677,888)
Notional Value		$ 140,504,130	$ 171,665,200
Number of Contracts | Contract		1,131	1,480
Maturity Date		Aug. 29, 2017	Aug. 29, 2017
CME SWAPS MARKETS (COMEX) [Member] | Silver [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(0.13%)	(0.10%)
Unrealized Appreciation/ (Depreciation)	[1]	$ (2,376,609)	$ (2,503,196)
Notional Value		$ 32,460,080	$ 41,251,620
Number of Contracts | Contract		388	516
Maturity Date		Dec. 27, 2017	Mar. 29, 2017
ICE FUTURES EUROPE [Member] | Brent Crude Oil [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(1.45%)	0.75%
Unrealized Appreciation/ (Depreciation)	[1]	$ (25,923,370)	$ 19,155,785
Notional Value		$ 216,162,810	$ 335,113,380
Number of Contracts | Contract		4,359	5,706
Maturity Date		Oct. 31, 2017	Oct. 31, 2017
LME CLEAR [Member] | Aluminum [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.49%	(0.02%)
Unrealized Appreciation/ (Depreciation)	[1]	$ 8,708,534	$ (551,306)
Notional Value		$ 83,292,313	$ 96,630,738
Number of Contracts | Contract		1,733	2,266
Maturity Date		Oct. 16, 2017	Oct. 16, 2017
LME CLEAR [Member] | Copper [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.25%	0.54%
Unrealized Appreciation/ (Depreciation)	[1]	$ 4,476,650	$ 13,883,069
Notional Value		$ 86,088,400	$ 104,798,238
Number of Contracts | Contract		577	758
Maturity Date		Feb. 19, 2018	Feb. 13, 2017
LME CLEAR [Member] | Zinc [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.45%	0.13%
Unrealized Appreciation/ (Depreciation)	[1]	$ 7,987,119	$ 3,269,739
Notional Value		$ 84,318,000	$ 102,650,000
Number of Contracts | Contract		1,222	1,600
Maturity Date		Dec. 18, 2017	Dec. 18, 2017
ICE FUTURES U.S. [Member] | Sugar [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(1.65%)	(0.25%)
Unrealized Appreciation/ (Depreciation)	[1]	$ (29,542,059)	$ (6,328,919)
Notional Value		$ 70,824,309	$ 125,014,680
Number of Contracts | Contract		4,579	5,985
Maturity Date		Sep. 29, 2017	Sep. 29, 2017
CME SWAPS MARKETS (NYMEX) [Member] | Natural Gas [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(0.15%)	0.82%
Unrealized Appreciation/ (Depreciation)	[1]	$ (2,676,347)	$ 20,938,774
Notional Value		$ 104,599,810	$ 160,443,840
Number of Contracts | Contract		3,451	4,517
Maturity Date		Aug. 29, 2017	Aug. 29, 2017
CME SWAPS MARKETS (NYMEX) [Member] | NY Harbor ULSD [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.05%	1.23%
Unrealized Appreciation/ (Depreciation)	[1]	$ 886,880	$ 31,579,715
Notional Value		$ 217,639,817	$ 342,794,222
Number of Contracts | Contract		3,382	4,666
Maturity Date		May 31, 2018	May 31, 2017
CME SWAPS MARKETS (NYMEX) [Member] | RBOB Gasoline [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(1.61%)	0.52%
Unrealized Appreciation/ (Depreciation)	[1]	$ (28,781,434)	$ 13,225,172
Notional Value		$ 224,053,704	$ 344,999,201
Number of Contracts | Contract		3,880	5,079
Maturity Date		Nov. 30, 2017	Nov. 30, 2017
CME SWAPS MARKETS (NYMEX) [Member] | WTI Crude Oil [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(1.97%)	2.42%
Unrealized Appreciation/ (Depreciation)	[1]	$ (35,085,593)	$ 61,784,092
Notional Value		$ 218,227,500	$ 343,155,480
Number of Contracts | Contract		4,575	6,278
Maturity Date		Feb. 20, 2018	Feb. 21, 2017

[1] Unrealized appreciation/(depreciation) is presented above, net by contract.