Schedule of Investments (Unaudited) - Futures Contracts - Futures [Member]		3 Months Ended	12 Months Ended
		Mar. 31, 2017 USD ($) Contract	Dec. 31, 2016 USD ($) Contract
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(2.58%)	3.95%
Unrealized Appreciation/ (Depreciation)	[1]	$ (57,836,271)	$ 101,032,417
Notional Value		$ 2,240,460,785	$ 2,557,065,161
Corn [Member] | CME SWAPS MARKETS (CBOT) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.14%	0.05%
Unrealized Appreciation/ (Depreciation)	[1]	$ 3,198,706	$ 1,268,361
Notional Value		$ 120,430,838	$ 129,584,812
Number of Contracts | Contract		6,351	6,981
Maturity Date		Sep. 14, 2017	Sep. 14, 2017
Soybean [Member] | CME SWAPS MARKETS (CBOT) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(0.08%)	0.12%
Unrealized Appreciation/ (Depreciation)	[1]	$ (1,732,230)	$ 3,209,119
Notional Value		$ 116,960,400	$ 133,400,362
Number of Contracts | Contract		2,452	2,697
Maturity Date		Nov. 14, 2017	Nov. 14, 2017
Wheat [Member] | CME SWAPS MARKETS (CBOT) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(1.03%)	(1.14%)
Unrealized Appreciation/ (Depreciation)	[1]	$ (23,189,480)	$ (29,220,100)
Notional Value		$ 115,610,650	$ 125,563,388
Number of Contracts | Contract		5,267	5,783
Maturity Date		Jul. 14, 2017	Jul. 14, 2017
Gold [Member] | CME SWAPS MARKETS (COMEX) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(0.52%)	(1.12%)
Unrealized Appreciation/ (Depreciation)	[1]	$ (11,639,126)	$ (28,677,888)
Notional Value		$ 168,855,700	$ 171,665,200
Number of Contracts | Contract		1,346	1,480
Maturity Date		Aug. 29, 2017	Aug. 29, 2017
Silver [Member] | CME SWAPS MARKETS (COMEX) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.06%	(0.10%)
Unrealized Appreciation/ (Depreciation)	[1]	$ 1,338,800	$ (2,503,196)
Notional Value		$ 42,825,185	$ 41,251,620
Number of Contracts | Contract		463	516
Maturity Date		Dec. 27, 2017	Mar. 29, 2017
Brent Crude Oil [Member] | ICE FUTURES EUROPE [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(0.32%)	0.75%
Unrealized Appreciation/ (Depreciation)	[1]	$ (7,160,045)	$ 19,155,785
Notional Value		$ 281,302,560	$ 335,113,380
Number of Contracts | Contract		5,192	5,706
Maturity Date		Oct. 31, 2017	Oct. 31, 2017
Aluminum [Member] | LME CLEAR [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.58%	(0.02%)
Unrealized Appreciation/ (Depreciation)	[1]	$ 12,899,013	$ (551,306)
Notional Value		$ 101,517,131	$ 96,630,738
Number of Contracts | Contract		2,061	2,266
Maturity Date		Oct. 16, 2017	Oct. 16, 2017
Copper [Member] | LME CLEAR [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.16%	0.54%
Unrealized Appreciation/ (Depreciation)	[1]	$ 3,617,131	$ 13,883,069
Notional Value		$ 100,727,081	$ 104,798,238
Number of Contracts | Contract		687	758
Maturity Date		Feb. 19, 2018	Feb. 13, 2017
Zinc [Member] | LME CLEAR [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.45%	0.13%
Unrealized Appreciation/ (Depreciation)	[1]	$ 10,140,381	$ 3,269,739
Notional Value		$ 101,013,375	$ 102,650,000
Number of Contracts | Contract		1,455	1,600
Maturity Date		Dec. 18, 2017	Dec. 18, 2017
Sugar [Member] | ICE FUTURES U.S. [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(0.67%)	(0.25%)
Unrealized Appreciation/ (Depreciation)	[1]	$ (15,113,772)	$ (6,328,919)
Notional Value		$ 104,343,624	$ 125,014,680
Number of Contracts | Contract		5,445	5,985
Maturity Date		Sep. 29, 2017	Sep. 29, 2017
Natural Gas [Member] | CME SWAPS MARKETS (NYMEX) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.39%	0.82%
Unrealized Appreciation/ (Depreciation)	[1]	$ 8,759,769	$ 20,938,774
Notional Value		$ 136,502,520	$ 160,443,840
Number of Contracts | Contract		4,114	4,517
Maturity Date		Aug. 29, 2017	Aug. 29, 2017
NY Harbor ULSD [Member] | CME SWAPS MARKETS (NYMEX) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(0.14%)	1.23%
Unrealized Appreciation/ (Depreciation)	[1]	$ (3,086,788)	$ 31,579,715
Notional Value		$ 282,057,854	$ 342,794,222
Number of Contracts | Contract		4,248	4,666
Maturity Date		May 31, 2017	May 31, 2017
RBOB Gasoline [Member] | CME SWAPS MARKETS (NYMEX) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(0.77%)	0.52%
Unrealized Appreciation/ (Depreciation)	[1]	$ (17,337,934)	$ 13,225,172
Notional Value		$ 284,527,547	$ 344,999,201
Number of Contracts | Contract		4,622	5,079
Maturity Date		Nov. 30, 2017	Nov. 30, 2017
WTI Crude Oil [Member] | CME SWAPS MARKETS (NYMEX) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(0.83%)	2.42%
Unrealized Appreciation/ (Depreciation)	[1]	$ (18,530,696)	$ 61,784,092
Notional Value		$ 283,786,320	$ 343,155,480
Number of Contracts | Contract		5,448	6,278
Maturity Date		Feb. 20, 2018	Feb. 21, 2017

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