Schedule of Investments - Futures Contracts - Futures [Member]		12 Months Ended
		Dec. 31, 2016 USD ($) Contract	Dec. 31, 2015 USD ($) Contract
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		3.95%	(17.68%)
Unrealized Appreciation/ (Depreciation)	[1]	$ 101,032,417	$ (351,279,993)
Notional Value		$ 2,557,065,161	$ 1,987,153,877
Corn [Member] | CME SWAPS MARKETS (CBOT) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.05%	(0.36%)
Unrealized Appreciation/ (Depreciation)	[1]	$ 1,268,361	$ (7,213,436)
Notional Value		$ 129,584,812	$ 119,104,350
Number of Contracts | Contract		6,981	6,348
Maturity Date		Sep. 14, 2017	Sep. 14, 2016
Soybean [Member] | CME SWAPS MARKETS (CBOT) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.12%	(0.09%)
Unrealized Appreciation/ (Depreciation)	[1]	$ 3,209,119	$ (1,789,744)
Notional Value		$ 133,400,362	$ 124,820,850
Number of Contracts | Contract		2,697	2,828
Maturity Date		Nov. 14, 2017	Nov. 14, 2016
Wheat [Member] | CME SWAPS MARKETS (CBOT) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(1.14%)	(0.60%)
Unrealized Appreciation/ (Depreciation)	[1]	$ (29,220,100)	$ (11,964,777)
Notional Value		$ 125,563,388	$ 116,777,362
Number of Contracts | Contract		5,783	4,833
Maturity Date		Jul. 14, 2017	Jul. 14, 2016
Gold [Member] | CME SWAPS MARKETS (COMEX) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(1.12%)	(0.35%)
Unrealized Appreciation/ (Depreciation)	[1]	$ (28,677,888)	$ (6,963,235)
Notional Value		$ 171,665,200	$ 170,940,160
Number of Contracts | Contract		1,480	1,609
Maturity Date		Aug. 29, 2017	Aug. 29, 2016
Silver [Member] | CME SWAPS MARKETS (COMEX) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(0.10%)	(0.06%)
Unrealized Appreciation/ (Depreciation)	[1]	$ (2,503,196)	$ (1,273,926)
Notional Value		$ 41,251,620	$ 41,892,105
Number of Contracts | Contract		516	607
Maturity Date		Mar. 29, 2017	Mar. 29, 2016
Brent Crude Oil [Member] | ICE FUTURES EUROPE [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.75%	(2.72%)
Unrealized Appreciation/ (Depreciation)	[1]	$ 19,155,785	$ (54,007,216)
Notional Value		$ 335,113,380	$ 220,801,200
Number of Contracts | Contract		5,706	4,973
Maturity Date		Oct. 31, 2017	Oct. 31, 2016
Aluminum [Member] | LME CLEAR [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(0.02%)	(0.23%)
Unrealized Appreciation/ (Depreciation)	[1]	$ (551,306)	$ (4,605,087)
Notional Value		$ 96,630,738	$ 91,292,350
Number of Contracts | Contract		2,266	2,372
Maturity Date		Oct. 16, 2017	Nov. 14, 2016
Copper [Member] | LME CLEAR [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.54%	0.12%
Unrealized Appreciation/ (Depreciation)	[1]	$ 13,883,069	$ 2,462,856
Notional Value		$ 104,798,238	$ 86,922,563
Number of Contracts | Contract		758	738
Maturity Date		Feb. 13, 2017	Feb. 15, 2016
Zinc [Member] | LME CLEAR [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.13%	(1.63%)
Unrealized Appreciation/ (Depreciation)	[1]	$ 3,269,739	$ (32,303,825)
Notional Value		$ 102,650,000	$ 89,236,406
Number of Contracts | Contract		1,600	2,225
Maturity Date		Dec. 18, 2017	Feb. 15, 2016
Sugar [Member] | ICE FUTURES U.S. [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		(0.25%)	0.97%
Unrealized Appreciation/ (Depreciation)	[1]	$ (6,328,919)	$ 19,297,530
Notional Value		$ 125,014,680	$ 133,604,442
Number of Contracts | Contract		5,985	8,126
Maturity Date		Sep. 29, 2017	Sep. 30, 2016
Natural Gas [Member] | CME SWAPS MARKETS (NYMEX) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.82%	(0.83%)
Unrealized Appreciation/ (Depreciation)	[1]	$ 20,938,774	$ (16,429,233)
Notional Value		$ 160,443,840	$ 117,554,230
Number of Contracts | Contract		4,517	4,663
Maturity Date		Aug. 29, 2017	Aug. 29, 2016
NY Harbor ULSD [Member] | CME SWAPS MARKETS (NYMEX) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		1.23%	(5.93%)
Unrealized Appreciation/ (Depreciation)	[1]	$ 31,579,715	$ (117,899,929)
Notional Value		$ 342,794,222	$ 212,814,109
Number of Contracts | Contract		4,666	4,169
Maturity Date		May 31, 2017	May 31, 2016
RBOB Gasoline [Member] | CME SWAPS MARKETS (NYMEX) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		0.52%	(0.63%)
Unrealized Appreciation/ (Depreciation)	[1]	$ 13,225,172	$ (12,489,060)
Notional Value		$ 344,999,201	$ 239,893,240
Number of Contracts | Contract		5,079	4,557
Maturity Date		Nov. 30, 2017	Nov. 30, 2016
WTI Crude Oil [Member] | CME SWAPS MARKETS (NYMEX) [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders’ Equity		2.42%	(5.34%)
Unrealized Appreciation/ (Depreciation)	[1]	$ 61,784,092	$ (106,100,911)
Notional Value		$ 343,155,480	$ 221,500,510
Number of Contracts | Contract		6,278	5,803
Maturity Date		Feb. 21, 2017	Feb. 22, 2016

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