Net Asset Value and Financial Highlights (Tables)

6 Months Ended

Jun. 30, 2016

Earnings Per Share [Abstract]

Schedule of Net Asset Value Per Share

Net asset value per Share is the net asset value of the Fund divided by the number of outstanding Shares at the date of each respective period presented.

	Three Months Ended						Six Months Ended
	June 30,						June 30,
	2016			2015			2016			2015
Net Asset Value
Net asset value per Share, beginning of period	$	13.30		$	17.08		$	13.35		$	18.40
Net realized and change in unrealized gain (loss) on    United States Treasury Obligations and Commodity    Futures Contracts		2.03			0.98			2.00			(0.30	)
Net investment income (loss) (a)		(0.02	)		(0.04	)		(0.04	)		(0.08	)
Net income (loss)		2.01			0.94			1.96			(0.38	)
Net asset value per Share, end of period	$	15.31		$	18.02		$	15.31		$	18.02
Market value per Share, beginning of period (b)	$	13.30		$	17.09		$	13.37		$	18.45
Market value per Share, end of period (b)	$	15.35		$	18.01		$	15.35		$	18.01
Ratio to average Net Assets *
Net investment income (loss)		(0.62	)%		(0.87	)%		(0.66	)%		(0.87	)%
Total expenses		0.88	%		0.88	%		0.89	%		0.89	%
Total Return, at net asset value **		15.11	%		5.50	%		14.68	%		(2.07	)%
Total Return, at market value **		15.41	%		5.38	%		14.81	%		(2.38	)%

(a) Based on average shares outstanding.

(b) The mean between the last bid and ask prices.

* Percentages are annualized.

** Percentages are not annualized.