Statements of Financial Condition (Unaudited) (USD $)	Jun. 30, 2012	Dec. 31, 2011
ASSETS
Short-term investments, at value (cost $163,429,056 and $175,594,508, respectively)	$ 163,433,325	$ 175,626,953
Deposits with brokers	35,198,742	44,193,777
Interest receivable	64,090	561,049
Unrealized appreciation on futures contracts, net	2,788,740
Other assets	224,651	200,745
Total assets	201,709,548	220,582,524
LIABILITIES
Call options written, at value (premiums received $1,504,277 and $1,428,047, respectively)	2,337,232	551,457
Unrealized depreciation on futures contracts, net		4,921,830
Payable for:
Distributions	1,336,790
Shares repurchased		315,845
Accrued expenses:
Management fees	196,679	229,634
Other	310,940	383,629
Total liabilities	4,181,641	6,402,395
SHAREHOLDERS' CAPITAL
Paid-in capital, unlimited number of shares authorized, 9,219,240 shares issued and outstanding at June 30, 2012 and 9,229,040 shares issued and outstanding at December 31, 2011	219,835,071	220,038,837
Accumulated undistributed earnings (deficit)	(22,307,164)	(5,858,708)
Total shareholders' capital (Net assets)	197,527,907	214,180,129
Total liabilities and shareholders' capital	201,709,548	220,582,524
Net assets	$ 197,527,907	$ 214,180,129
Shares outstanding	9,219,240	9,229,040
Net asset value per share outstanding (net assets divided by shares outstanding)	$ 21.43	$ 23.21
Market value per share outstanding	$ 20.40	$ 20.30