Amendment Flag Current Fiscal Year End Date Document and Entity Information [Abstract] Document And Entity Information [Abstract]. Document Fiscal Period Focus Document Fiscal Year Focus Document Period End Date Document Type Entity Central Index Key Entity Common Stock, Shares Outstanding Entity Filer Category Entity Registrant Name Accrued Liabilities Accrued liabilities Additional Paid in Capital Paid-in-capital Assets Total assets Assets [Abstract] Assets Due from Related Parties Due from related parties Due to Related Parties Due to related parties Short-term investments, at fair value (cost $102,429) Liabilities Total liabilities Liabilities and Equity Total liabilities and shareholders' capital Liabilities and Equity [Abstract] Liabilities and shareholders' capital Market Value Per Share Market Value Per Share. Market value per share Net Assets Per Share Net asset value per share Net Assets Per Share. Payable On Open Futures Contracts Payable On Open Futures Contracts. Payable on open futures contracts Receivable On Open Futures Contracts Receivable On Open Futures Contracts. Receivable on open futures contracts Restricted Cash and Cash Equivalents Segregated cash held by broker Retained Earnings (Accumulated Deficit) Accumulated earnings (deficit) Shares, Outstanding Shares outstanding Statement of Financial Condition [Abstract] Total shareholders' capital Stockholders' Equity Attributable to Parent [Abstract] Shareholders' capital Total U.S. Futures [Member] Investment [Axis] Investment [Domain] Investment Maturity Date Instant The maturity date of the investment as an instant type disclosure. Maturity Date Investment Owned, at Cost Short-term investments, at cost Investment Owned, at Fair Value Fair Value Investment Owned, Balance, Contracts Number of Contracts Investment Owned, Balance, Principal Amount Principal Amount Investment Owned Fair Value At Trade Date Fair value of investment at trade date. Fair Value at Trade Date Investment Owned, Percent of Net Assets Short-Term Investments, percentage of shareholders' capital Investment Owned Recognized Unrealized Appreciation Depreciation Net Investment Owned, Recognized Unrealized Appreciation Depreciation, Net. Unrealized Appreciation/(Depreciation) JP Morgan 100% U.S. Treasury Securities Money Market Fund Capital [Member] JP Morgan 100% U.S. Treasury Securities Money Market Fund Capital [Member]. S and P 500 E Mini Index Futures, DEC11 [Member] S&P 500 E Mini Index Futures, SEPT11 [Member]. Schedule of Investments [Abstract] Short-term Investments [Abstract] Short-Term Investments Total Short-Term Investments [Member] Statement [Line Items] Statement [Table] Thirty Year U.S. Treasury Bond Futures, DEC11 [Member] 30 Year U.S. Treasury Bond Futures, SEPT11 [Member]. U.S. Futures [Abstract] U.S. Futures [Abstract]. U.S. Futures U.S. Treasury Bill, Zero Coupon, due 5/26/11 [Member] U.S. Treasury Bill, Zero Coupon, due 5/26/11 [Member]. Stock Issued During Period, Shares, New Issues Addition of shares, number of shares Stock Issued During Period, Shares, Period Increase (Decrease) Net increase/(decrease) in Shareholders' Capital resulting from share transactions, shares Stock Redeemed or Called During Period, Shares Redemption of shares, number of shares Accretion (Amortization) of Discounts and Premiums, Investments Accretion of discount on United States Treasury Obligations Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income/(loss) to net cash used in operating activities: Cash Cash, beginning of period Cash, end of period Cash and Cash Equivalents, Period Increase (Decrease) Net decrease in cash Increase (Decrease) in Accrued Liabilities Increase in accrued liabilities Increase (Decrease) in Due from Related Parties Increase in due from related parties Increase (Decrease) in Due to Related Parties Increase in due to related parties Increase (Decrease) in Other Accounts Payable Increase in payable on open futures contracts Increase (Decrease) in Receivables Increase in receivables on open futures contracts Increase Decrease In Segregated Cash Balances For Futures Agreements The increase (decrease) in segregated cash balances for futures agreements. Increase in segregated cash balances for futures agreements Net Cash Provided by (Used in) Financing Activities Net cash provided by financing activities Net Cash Provided by (Used in) Financing Activities [Abstract] Cash flows provided by financing activities: Net Cash Provided by (Used in) Operating Activities Net cash used in operating activities Net Cash Provided by (Used in) Operating Activities [Abstract] Cash flows used in operating activities: Net income/(loss) Payments for (Proceeds from) Investments Net purchase of short-term investments Payments for Repurchase of Common Stock Paid on redemption of shares Proceeds from Issuance of Common Stock Proceeds from sale of shares Statement of Cash Flows [Abstract] Nature of Operations [Text Block] Organization Organization [Abstract] Organization [Abstract]. Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies Summary of Significant Accounting Policies [Abstract] Summary Of Significant Accounting Policies [Abstract]. Investments [Abstract] Investment [Text Block] Investments Agreements [Abstract] Agreements [Abstract]. Agreements Note [Text Block] Agreements Note [Text Block]. Agreements Creations and Redemptions [Abstract] Stockholders' Equity Note Disclosure [Text Block] Creations and Redemptions Concentration Risk Disclosure [Text Block] Risk Risk [Abstract] Profit and Loss Allocations and Distributions [Abstract] Profit And Loss Allocations And Distributions [Abstract]. Profit And Loss Allocations And Distributions Note [Text Block] Profit And Loss Allocations And Distributions Note [Text Block]. Profit and Loss Allocations and Distributions Indemnifications [Abstract] Indemnifications [Abstract]. Indemnifications [Text Block] Indemnifications [Text Block]. Indemnifications New Accounting Pronouncement [Abstract] Modified Modified Modified Termination [Abstract] Termination [Abstract]. Termination Disclosure [Text Block] Termination Disclosure [Text Block]. Termination Net Asset Value and Financial Highlights [Abstract] Net Asset Value And Financial Highlights [Abstract]. Net Asset Value And Financial Highlights [Text Block] Net Asset Value And Financial Highlights [Text Block]. Net Asset Value and Financial Highlights Subsequent Events [Abstract] Subsequent Events [Text Block] Subsequent Events Administrative Accounting And Custodian Fees Administrative, Accounting, And Custodian Fees. Administrative/Accounting/Custodian Fees Asset Management Costs Management fee Audit Fees Audit Fees. Audit fees Change In Unrealized Gain Loss [Abstract] Change In Unrealized Gain Loss [Abstract]. Change in Unrealized Gain/(Loss) Distribution Fees Distribution Fees. Distribution fees Exchange Fees Expense Reimbursement Expense Reimbursement. Less - expense reimbursement Floor Brokerage Brokerage commission and fees Gain (Loss) on Investments Net realized and unrealized gain/(loss) General Insurance Expense Insurance Statements of Operations [Abstract] Interest Income, Operating Interest Income Net Investment Income/(Loss) Legal Fees Legal fees Listing and Calculation Agent fees Net Realized Gain Loss [Abstract] Net Realized Gain Loss [Abstract]. Net Realized Gain/(Loss) Net Realized and Unrealized Gain (Loss) on Trading Securities [Abstract] Net Realized and Unrealized Gain/(Loss) on Investment Activity Operating Expenses Total Expenses Operating Expenses [Abstract] Expenses Operating Expenses Net Net Expenses Operating Expenses, Net. Other Cost and Expense, Operating Other Expenses Futures Contracts Reduction In Management Fee Reduction In Management Fee. Less - reduction in management fee Revenues Total Investment Income Revenues [Abstract] Investment Income Revenues, Excluding Interest and Dividends Other Income Supplies and Postage Expense Printing and Postage Tax Return Preparation Fees Tax Return Preparation Fees. Tax Return preparation fees Futures Contracts Addition of 200,000 shares Increase (Decrease) In Shareholders Capital From Operations [Abstract] Increase (Decrease) In Shareholders Capital From Operations [Abstract]. Increase/(decrease) in Shareholders' Capital from operations Increase Decrease In Shareholders Capital From Share Transactions Increase (Decrease) In Shareholders Capital From Share Transactions. Increase (Decrease) In Shareholders Capital From Share Transactions [Abstract] Increase (Decrease) In Shareholders Capital From Share Transactions [Abstract]. Increase/(decrease) in Shareholders' Capital resulting from share transactions Investment Income, Net Net investment income/(loss) Net Income (Loss) Attributable to Parent Net Income/(Loss) Net increase/(decrease) in Shareholders' Capital resulting from share transactions Realized Investment Gains (Losses) Net realized gain/(loss) Redemption of 100,000 shares Statement of Changes in Shareholders' Capital [Abstract] Stockholders' Equity Attributable to Parent Shareholders' Capital at beginning of period Shareholders' Capital at end of period Stock Issued During Period, Value, New Issues Stock Redeemed or Called During Period, Value Unrealized Gain (Loss) on Investments Change in net unrealized appreciation/(depreciation) Description of New Accounting Pronouncements Not yet Adopted [Text Block] New Accounting Pronouncement New Accounting Pronouncement [Abstract]