FINANCIAL HIGHLIGHTS (Tables)

12 Months Ended

Dec. 31, 2017

Supplemental Financial Information Disclosure [Abstract]

Schedule Of Per Unit Performance Data and Other Financial Data

The following table presents per share performance data and other supplemental financial data for the years ended December 31, 2017, 2016 and 2015 for the shareholders. This information has been derived from information presented in the financial statements.

	Year ended December 31, 2017			Year ended December 31, 2016			Year ended December 31, 2015
Per Share Operating Performance:
Net asset value, beginning of year	$	15.70		$	12.22		$	22.39
Total income (loss)		2.61			3.60			(10.00)
Net expenses		(0.13)			(0.12)			(0.17)
Net increase (decrease) in net asset value		2.48			3.48			(10.17)
Net asset value, end of year	$	18.18		$	15.70		$	12.22

Total Return		15.80	%		28.48	%		(45.42)	%

Ratios to Average Net Assets
Total income (loss)		16.22	%		34.23	%		(46.52)	%
Management fees		0.75	%		0.75	%		0.75	%
Total expenses excluding management fees		0.48	%		0.32	%		0.30	%
Expenses waived		(0.33)	%		(0.17)	%		(0.15)	%
Net expenses excluding management fees		0.15	%		0.15	%		0.15	%
Net income (loss)		15.32	%		33.33	%		(47.42)	%