Document and Entity Information [Abstract] Document And Entity Information [Abstract] Document Type Amendment Flag Document Period End Date Document Fiscal Year Focus Document Fiscal Period Focus Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Entity Filer Category Entity Common Stock, Shares Outstanding Statements of Financial Condition [Abstract] Short-term Investments Short-Term Investments Short-term investments, at value (cost $163,429,056 and $175,594,508, respectively) Other Liabilities Other Total liabilities Liabilities Paid-in capital, unlimited number of shares authorized, 9,267,040 shares issued and outstanding at March 31, 2011 and December 31, 2010, respectively 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 Retained Earnings (Accumulated Deficit) Accumulated undistributed earnings (deficit) Total liabilities and shareholders' capital Liabilities and Equity Common Stock, shares outstanding Shares outstanding Common stock, shares outstanding Net Asset Value Per Share Outstanding Net asset value per share-end of period Net asset value per share-beginning of period Net asset value per share outstanding (net assets divided by shares outstanding) Net asset value per share outstanding. Market value per share outstanding Market value per share-end of period Market value per share-beginning of period Market value per share outstanding Market value per share outstanding. Short-term investments, at cost Short-term investments, at cost Short-term investments, at cost Common Stock, shares issued Common stock, shares issued Common Share Authorized Unlimited Common stock, shares authorized Common share authorized unlimited. Schedule of Investments [Abstract] Investment Holdings, Schedule of Investments [Text Block] Schedule of Investments Statements of Operations [Abstract] Interest and Dividend Income, Operating [Abstract] Investment Income: Interest Interest Revenues Total Investment Income Operating Expenses [Abstract] Expenses: Asset Management Costs Management fees Brokerage commissions Brokerage commissions Custodian's fees and expenses Custodian's fees and expenses Trustees' fees and expenses Trustees' fees and expenses Professional fees Professional fees Shareholders' reports-printing and mailing expenses Shareholder reporting expense Other expenses Other expenses Investment Income Net Net investment income (loss) Net investment income (loss) Realized Investment Gains (Losses) [Abstract] Net realized gain (loss) from: Investment Owned, Unrecognized Unrealized Appreciation (Depreciation), Net [Abstract] Change in net unrealized appreciation (depreciation) of: Unrealized Gain On Call Options Written Call options written Call options written Net Realized or Unrealized Gain (Loss) on Trading Securities Net realized gain (loss) and change in net unrealized appreciation (depreciation) Net income (loss) Net income (loss) Net income (loss) Earnings Per Share, Basic Net income (loss) per weighted-average share Weighted Average Number of Shares Outstanding, Basic Weighted-average shares outstanding Statements of Changes in Shareholders' Capital [Abstract] Increase (Decrease) in Stockholders' Equity [Roll Forward] Net increase (decrease) in shareholders' capital resulting from operations: Realized Gain Loss From Short Term Investments Short-term investments Realized gain (loss) from short-term investments. Realized Gain Loss From Futures Contracts Futures contracts Realized gain (loss) from futures. Realized Gain Loss From Call Options Written Call options written Realized gain (loss) from call options written. Distributions to shareholders Distributions to shareholders Shares, Issued Shares-end of period Shares-beginning of period Issuance of shares Issuance of shares Statements of Cash Flows [Abstract] Payments to Acquire Short-term Investments Purchases of short-term investments Proceeds from Sale, Maturity and Collection of Short-term Investments Proceeds from sales and maturities of short-term investments Cash paid for call options written Premiums paid for call options written Cash paid for call options written. Premiums Received for Call Options Written Premiums received for call options written Premiums received for call options written Accretion (Amortization) of Discounts and Premiums, Investments Amortization (Accretion) Increase (Decrease) in Margin Deposits Outstanding Deposits with brokers Increase (Decrease) in Accrued Interest Receivable, Net Interest receivable Increase (Decrease) in Other Operating Assets Other assets Increase Decrease in Accrued Management Fees Accrued management fees Accrued management fees Increase decrease in accrued management fees Increase (Decrease) in accrued other liabilities Other accrued expenses Change in Net Unrealized Appreciation Depreciation of [Abstract] Change in net unrealized (appreciation) depreciation of: Change in net unrealized appreciation depreciation of. Payments of Dividends Cash distributions to shareholders Net cash provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Net increase (decrease) in cash Cash and Cash Equivalents, Period Increase (Decrease) Cash and Cash Equivalents, at Carrying Value Cash - end of period Cash - beginning of period Summary of Significant Accounting Policies [Abstract] Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivative Instruments and Hedging Activities Related Party Transactions Disclosure [Text Block] Related Parties Basis of Accounting, Policy [Policy Text Block] Basis of Accounting Fair Value Measurement, Policy [Policy Text Block] Fair Value Measurements Income Tax, Policy [Policy Text Block] Income Taxes Commitments and Contingencies, Policy [Policy Text Block] Commitments and Contingencies Commissions Expense, Policy [Policy Text Block] Brokerage Commissions and Fees Investment, Policy [Policy Text Block] Investment Valuation Distributions [Policy Text Block] Distributions Disclosure for accounting policy of distributions. Commodity Contract [Member] Number of Contracts [Member] Fair Value, Option, Qualitative Disclosures Related to Election [Table] Options Written Options written, Premiums Received Premiums received for options written. Options Terminated In Closing Purchase Transactions Options terminated in closing purchase transactions, Premiums Received Premiums related to options terminated in closing transactions. Options Expired Options expired, Premiums Received Premiums related to options expired. Fair Value, Option, Qualitative Disclosures Related to Election [Line Items] Fair Value, Inputs, Level 1 [Member] Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Level 2 [Member] Fair Value, Inputs, Level 3 [Member] Level 3 [Member] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Investments [Abstract] Short-Term Investments: Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Investments, Fair Value Disclosure Total Derivative Instrument Detail [Abstract] Fair value of all derivative instruments held by the Fund Derivatives: Summary of Significant Accounting Policies (Textual) [Abstract] Summary of Significant Accounting Policies (Textual) [Abstract] Summary of significant accounting policies. Schedule of Fair Value, Off-balance Sheet Risks [Table] Financial Instrument [Axis] Types of Financial Instruments [Domain] Call Option [Member] Call option [Member] Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] Percentage of Fund's Assets Committed to Secure Funds Futures and Forward Contract Positions Percentage of Fund's assets committed to secure Fund's futures and forward contract positions Percentage of fund's assets committed to secure funds futures and forward contract positions. Derivative By Nature [Axis] Derivative Name [Domain] Derivative Instrument Risk [Axis] Derivative [Line Items] Derivative Instruments, Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Table] Derivative Contract Type [Domain] Net Investment Income Loss Per Share Net investment income (loss) Net investment income loss per share. Net Realized And Unrealized Gain Loss Per Share Net realized and unrealized gain (loss) Net realized and unrealized gain loss per share. Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unobservable Input, Gains (Losses), Net [Abstract] Net Asset Value: Market Value [Abstract] Market Value: Market value. Ratios To Average Net Assets [Abstract] Ratios to Average Net Assets: Ratios to average net assets. Net Returns [Abstract] Total Returns: Total returns. Percentage Return On Net Asset value Based on Net Asset Value Percentage return on net asset value. Percentage Return On Market Value Per Share Based on Market Value Percentage return on market value per share. Short Term Investment [Abstract] Short Term Investments Short term investments. Schedule of Investments [Table] Schedule of Investments [Line Items] Commodity Group [Abstract] Commodity Group Commodity group. Contract Position Contract Position Contract position. Ice Brent Crude Oil Futures [Member] ICE Brent Crude Oil Futures [Member] Ice Brent Crude Oil Futures. Nymex Crude Oil Futures [Member] NYMEX Crude Oil Futures [Member] Nymex Crude Oil Futures. Nymex Crude Oil Futures One [Member] NYMEX Crude Oil Futures 1 [Member] Nymex Crude Oil Futures. Ice Gas Oil Futures [Member] ICE Gas Oil Futures [Member] Ice Gas Oil Futures. Ice Gas Oil Futures One [Member] ICE Gas Oil Futures 1 [Member] Ice Gas Oil Futures. Nymex Heating Oil Futures [Member] NYMEX Heating Oil Futures [Member] Nymex Heating Oil Futures. Nymex Heating Oil Futures One [Member] NYMEX Heating Oil Futures 1 [Member] Nymex Heating Oil Futures. Aggregate Heating Oil [Member] Aggregate Heating Oil [Member] Aggregate Heating. Nymex Natural Gas Futures [Member] NYMEX Natural Gas Futures [Member] Nymex Natural Gas Futures. Nymex Natural Gas Futures One [Member] NYMEX Natural Gas Futures 1 [Member] Nymex Natural Gas Futures. Aggregate Natural Gas [Member] Total Natural Gas. Aggregate Natural Gas [Member] Nymex Gasoline Rbob Futures [Member] NYMEX Gasoline Rbob Futures [Member] Nymex Gasoline Rbob Futures. Nymex Gasoline Rbob Futures One [Member] NYMEX Gasoline Rbob Futures 1 [Member] Nymex Gasoline Rbob Futures. Aggregate Unleaded Gas [Member] Aggregate Unleaded Gas [Member] Total Unleaded Gas. Derivative [Table] Derivative, Notional Amount Notional Amount at Value Lme Primary Aluminum Futures [Member] LME Primary Aluminum Futures [Member] Lme Primary Aluminum Futures. Lme Primary Aluminum Futures One [Member] LME Primary Aluminum Futures 1 [Member] Lme Primary Aluminum Futures. Lme Primary Aluminum Futures Two [Member] LME Primary Aluminum Futures 2 [Member] Lme Primary Aluminum Futures. Aggregate Aluminum [Member] Total Aluminum. Aggregate Aluminum [Member] Cec Copper Futures [Member] CEC Copper Futures [Member] Cec Copper Futures. Lme Copper Futures [Member] LME Copper Futures [Member] Lme Copper Futures. Lme Copper Futures One [Member] LME Copper Futures 1 [Member] Lme Copper Futures. Aggregate Copper [Member] Total Copper. Aggregate Copper [Member] Lme Nickel Futures [Member] LME Nickel Futures [Member] Lme Nickel Futures. Lme Zinc Futures [Member] LME Zinc Futures [Member] Lme Zinc Futures. Lme Zinc Futures One [Member] LME Zinc Futures 1 [Member] Lme Zinc Futures. Lme Zinc Futures Two [Member] LME Zinc Futures 2 [Member] Lme Zinc Futures. Aggregate Zinc [Member] Total Zinc. Aggregate Zinc [Member] Lme Lead Futures [Member] LME Lead Futures [Member] Lme Lead Futures. Cbot Corn Futures [Member] CBOT Corn Futures [Member] Cbot Corn Futures. Cbot Soybean Futures [Member] CBOT Soybean Futures [Member] Cbot Soybean Futures. Cbot Wheat Futures [Member] CBOT Wheat Futures [Member] Cbot Wheat Futures. Kcbt Wheat Futures [Member] KCBT Wheat Futures [Member] Kcbt Wheat Futures. Aggregate Wheat [Member] Total Wheat. Aggregate Wheat [Member] Cbot Soybean Meal Futures [Member] CBOT Soybean Meal Futures [Member] Cbot Soybean Meal Futures. Cbot Soybean Oil Futures [Member] CBOT Soybean Oil Futures [Member] Cbot Soybean Oil Futures. Cbot Soybean Oil Futures One [Member] CBOT Soybean Oil Futures 1 [Member] Cbot Soybean Oil Futures. Aggregate Soybean Oil [Member] Total Soybean Oil. Aggregate Soybean Oil [Member] Cec Gold Futures [Member] CEC Gold Futures [Member] Cec Gold Futures. Cec Silver Futures [Member] CEC Silver Futures [Member] Cec Silver Futures. Nymex Platinum Futures [Member] NYMEX Platinum Futures [Member] Nymex Platinum Futures. Nymex Palladium Futures [Member] NYMEX Palladium Futures [Member] Nymex Palladium Futures. Ice Cotton Futures [Member] ICE Cotton Futures [Member] Ice Cotton Futures. Ice Sugar Futures [Member] ICE Sugar Futures [Member] Ice Sugar Futures. Ice Coffee C Futures [Member] ICE Coffee C Futures [Member] Ice Coffee C Futures. Ice Coffee C Futures One [Member] ICE Coffee C Futures 1 [Member] Ice Coffee C Futures. Liffe Coffee Robusta Futures [Member] LIFFE Coffee Robusta Futures [Member] Liffe Coffee Robusta Futures. Aggregate Coffee [Member] Total Coffee. Aggregate Coffee [Member] Ice Cocoa Futures [Member] ICE Cocoa Futures [Member] Ice Cocoa Futures. Cme Live Cattle Futures [Member] CME Live Cattle Futures [Member] Cme Live Cattle Futures. Cme Live Cattle Futures One [Member] CME Live Cattle Futures 1 [Member] Cme Live Cattle Futures. Aggregate Live Cattle [Member] Total Live Cattle. Aggregate Live Cattle [Member] Cme Lean Hog Futures [Member] CME Lean Hog Futures [Member] Cme Lean Hog Futures. Cme Lean Hog Futures One [Member] CME Lean Hog Futures 1 [Member] Cme Lean Hog Futures. Cme Lean Hog Futures Two [Member] CME Lean Hog Futures 2 [Member] Cme Lean Hog Futures. Aggregate Lean Hogs [Member] Total Lean Hogs. Aggregate Lean Hogs [Member] Cme Feeder Cattle Futures [Member] CME Feeder Cattle Futures [Member] Cme Feeder Cattle Futures. Industrial Metals [Member] Industrial Metals. Industrial Metals [Member] Foods and Fibers [Member] Foods and Fibers. Foods and Fibers [Member] Futures Options, Value Futures Options, Value Futures options. Investment Holding [Axis] Investment Holding [Domain] Investment Sector [Axis] Investment Sector [Domain] Energy Related Derivative [Member] Energy [Member] Option Indexed to Issuer's Equity, Strike Price Strike Price Cbot Corn Futures Options One [Member] CBOT Corn Futures 1 [Member] CBOT corn futures options 1. Aggregate Corn [Member] Aggregate corn. Aggregate Corn [Member] Cbot Wheat Futures Options One [Member] CBOT Wheat Futures 1 [Member] Cbot wheat futures options 1. Kcbt Wheat Futures Options One [Member] KCBT Wheat Futures 1 [Member] KCBT wheat futures 1. Ice Cotton Futures One [Member] ICE Cotton Futures 1 [Member] ICE cotton futures 1. Aggregate Cotton [Member] Aggregate cotton. Aggregate Cotton [Member] Forward Contracts [Policy Text Block] Forward Contracts Forward contracts. Derivatives, Policy [Policy Text Block] Futures Contracts Derivative, Number of Instruments Held Outstanding, end of the period, Number of Contracts Outstanding, beginning of period, Number of Contracts Options Written Number Of Contracts Options written, Number of Contracts Options written number of contracts. Options Terminated In Closing Purchase Transactions Number Of Contracts Options terminated in closing purchase transactions, Number of Contracts Options terminated in closing purchase transactions number of contracts. Options Expired Number Of Contracts Options expired, Number of Contracts Options expired number of contracts. Net Asset by Range [Axis] Net asset by range. Net Asset by Range [Domain] Net asset by range. Range One [Member] For the first $500 million [Member] Range one. Range Two [Member] For the next $500 million [Member] Range two. Range Three [Member] For the next $500 million [Member] Range three. Range Four [Member] For the next $500 million [Member] Range four. Range Five [Member] For net assets over $2 billion [Member] Range five. Average Daily Net Assets [Abstract] Management fee according to fund's average daily net assets Average daily net assets. Assets Invested In Cash Equivalents Period Maximum Period of assets invested in cash equivalents Assets invested in cash equivalents period maximum. Assets Invested In Cash Or Treasury Bills Period Maximum Period of assets invested in cash or treasury bills Assets invested in cash or treasury bills period maximum. Unrealized Depreciation On Futures Contracts Net Unrealized depreciation on futures contracts, net Unrealized depreciation on futures contracts net. Realized Gain On Short Term Investments Short-term investments Short-term investments Realized gain on short term investments. Realized Gain On Future Contracts Futures contracts Realized gain on future contracts. Realized Gain On Call Options Written Call options written Call options written Realized gain on call options written. Unrealized Gain On Short Term Investments Short-term investments Short-term investments Unrealized gain on short term investments. Derivative Asset, Fair Value, Net Total of Asset Derivatives Derivative Liability, Fair Value, Net Total of Liability Derivatives Total of Liability Derivatives Ratio Of Net Investment Income Loss To Average Net Assets Net investment income (loss) Ratio of net investment income loss to average net assets. Ratio Of Expense To Average Net Assets Expenses Ratio of expense to average net assets. Financial Instruments Owned Us Government And Agency Obligations Interest Rate Short-Term Investments, Coupon Financial instruments owned us government and agency obligations interest rate. Financial Instruments Owned Us Government And Agency Obligations Maturity Date Short-Term Investments, Maturity Financial instruments owned us government and agency obligations maturity date. Financial Instruments Owned Us Government And Agency Obligations Credit Ratings Short-Term Investments, Ratings Financial instruments owned us government and agency obligations credit ratings. Assets Sold Under Agreements To Repurchase Maturity Date Repurchase Agreements, Maturity Assets sold under agreements to repurchase maturity date. Assets Sold Under Agreements To Repurchase Credit Ratings Repurchase Agreements, Ratings Assets sold under agreements to repurchase credit ratings. US Government and Government Agencies and Authorities [Member] Federal Home Loan Mortgage Corporation [Member] US Treasury Securities [Member] U.S. Treasury Bills [Member] Schedule of Cost-method Investments [Axis] Major Types of Debt and Equity Securities [Domain] Schedule Of Share Based Compensation Stock Options Activity [Abstract] Transactions in call options Schedule of share based compensation stock options activity. Derivative Instruments and Hedging Activities [Abstract] Related Parties [Abstract] Purchasing and Selling Fund Shares [Abstract] Purchasing and selling Fund shares Purchasing and selling fund shares. Short Term Investment by Maturity Type [Axis] Short term investment by maturity type. Short Term Investment by Maturity Type [Domain] Short term investment by maturity type. Short Term Investment One [Member] 8/07/12 [Member] Short term investment one. Short Term Investment Two [Member] 8/28/12 [Member] Short term investment two. Short Term Investment Three [Member] 9/04/12 [Member] Short term investment three. Short Term Investment Four [Member] 11/30/12 [Member] Short term investment four. Short Term Investment Five [Member] 8/23/12 [Member] Short term investment five. Short Term Investment Six [Member] 11/15/12 [Member] Short term investment six. Short Term Investment Seven [Member] 2/07/13 [Member] Short term investment seven. Short Term Investment Eight [Member] 5/30/13 [Member] Short term investment eight. Contract Expiration Contract expiration. Contract Expiration Number of Contracts Number of Contracts Number of contracts. Financial Instruments Owned Us Government and Agency Obligations [Abstract] Short-Term Investments U.S. Government and Agency Obligations Financial instruments owned Us government and agency obligations. Assets Sold Under Agreements to Repurchase [Abstract] Repurchase Agreements Assets sold under agreements to repurchase. Aggregate Crude Oil [Member] Aggregate Crude Oil [Member] Aggregate crude oil. Ice Brent Crude Oil Futures One [Member] ICE Brent Crude Oil Futures 1 [Member] Fixed Income Security Maturity Period Maturity of prices of fixed-income securities Fixed income security maturity period. Management Fees Payable Management fees Management fees payable. Financial Instruments Owned Us Government and Agency Obligations Principal Amount Short-Term Investments, Principal Amount Financial instruments owned U.S. government and agency obligations principal amount. Call Options Written [Member] Call Options Written [Member] Derivatives Options [Policy Text Block] Options Contracts Derivatives options. Collateral Investments [Policy Text Block] Collateral Investments Collateral investments. Investment Transactions [Policy Text Block] Investment Transactions Investment transactions. Investment Income [Policy Text Block] Investment income. Investment Income Expenses Recognition [Policy Text Block] Expense Recognition Expenses recognition. Custodian Fee Credit [Policy Text Block] Custodian Fee Credit Custodian fee credit. Net Asset Value [Policy Text Block] Calculation of Net Asset Value Net asset value. Financial Instruments Risk Policy Text Block Financial Instrument Risk Financial instruments risk. Schedule of Transactions in Call Options Written [Table Text Block] Transactions in call options Schedule of transactions in call options written. Schedule of Funds Fair Value Measurement [Table Text Block] Fund's fair value measurement Schedule of funds fair value measurement. Schedule of Management Fee Payable According to Funds Average Daily Net Assets [Table Text Block] Management fee according to fund's average daily net assets Schedule of management fee payable according to funds average daily net assets. Schedule of Net Realized Gains Losses and Change in Net Unrealized Appreciation Depreciation Recognized on Derivative Instruments and Primary Underlying Risk Exposure [Table Text Block] Net realized gain (loss) and change in net unrealized appreciation (depreciation) recognized on derivative instruments Schedule of net realized gains losses and change in net unrealized appreciation depreciation recognized on derivative instruments and primary underlying risk exposure. Schedule of Net Asset Value Market Value Ratios to Average Net Assets and Returns [Table Text Block] Purchasing and selling Fund shares Schedule of net asset value market value ratios to average net assets and returns. Average Derivative Number of Instruments Held Average number of contracts outstanding Average derivative number of instruments held. Investment Owned Recognized Unrealized Appreciation Depreciation Net Unrealized Appreciation (Depreciation) Investment owned recognized unrealized appreciation depreciation, net. Payable For Shares Repurchased Shares repurchased Payable for shares repurchased. Stock Repurchased During Period, Value Repurchase of shares Stock Repurchased During Period, Shares Repurchase of shares Payments for Repurchase of Common Stock Cash paid for shares repurchased Treasury Stock [Text Block] Share Repurchase Program Share Repurchase Program [Abstract] Financial Highlights [Abstract] Statement of Financial Highlights Text Block Statement of financial highlights. Financial Highlights Schedule of Repurchase Agreements [Table Text Block] Transactions in share repurchases Stock Issued or Granted During Period, Share-based Compensation [Abstract] Transactions in share repurchases Treasury Stock Acquired, Average Cost Per Share Weighted average price per share repurchased Share Repurchase Program (Textual) [Abstract] Share repurchase program. Share Repurchase Program (Textual) [Abstract] Stock Repurchase Program, Number of Shares Authorized to be Repurchased outstanding common shares Short Term Investment Nine [Member] 7/02/12 [Member] Short term investment nine. Short Term Investment Ten [Member] 5/31/12 [Member] Short term investment ten. Nymex Crude Oil Futures Two [Member] Nymex Crude Oil Futures 2 [Member] Nymex crude oil futures Nymex Natural Gas Futures Two [Member] Nymex natural gas futures. Nymex Natural Gas Futures 2 [Member] Lme Primary Aluminum Futures Three [Member] Lme Primary Aluminum Futures 3 [Member] Lme primary aluminum futures. Cbot Wheat Futures Options Two [Member] Cbot wheat futures options. CBOT Wheat Futures Options 2 [Member] Ice Sugar Future One [Member] Ice sugar future. Ice Sugar Future 1 [Member] Agricultural Production [Member] Agriculturals [Member] Agricultural production. Precious Metal [Member] Precious Metals [Member] Precious metal. Livestock [Member] Livestock [Member] Livestock. Forward Contracts [Member] Forward contracts [Member] Summary of Significant Accounting Policies (Additional Textual) [Abstract] Summary of significant accounting policies. Summary of Significant Accounting Policies (Additional Textual) [Abstract] Aggregate Outstanding Common Shares to Repurchase Percentage of outstanding common shares available for repurchase Aggregate outstanding common shares to repurchase. Organization (Textual) [Abstract] Organization (Textual) [Abstract] Organization. Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage Percentage of stake acquired in Gresham Assets [Abstract] ASSETS Stockholders Equity Shareholders' capital-end of period Shareholders' capital-beginning of period Total shareholders' capital (Net assets) Net assets Liabilities [Abstract] LIABILITIES Accounts Payable and Accrued Liabilities [Abstract] Payable for: Accrued expenses [Abstract] Accrued expenses: Stockholders' Equity Attributable to Parent [Abstract] SHAREHOLDERS' CAPITAL Unrealized Gain (Loss) on Investments [Abstract] Change in net unrealized appreciation (depreciation) of: Net Cash Provided by (Used in) Operating Activities [Abstract] Cash flows from operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities: Increase (Decrease) in Operating Assets [Abstract] (Increase) Decrease in: Increase (Decrease) in Operating Liabilities [Abstract] Increase (Decrease) in: Trading Securities, Realized Gain (Loss) [Abstract] Net realized (gain) loss from: Net Cash Provided by (Used in) Financing Activities [Abstract] Cash flows from financing activities: Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Organization Organization [Abstract] Schedule of Derivatives Instruments Statements of Financial Performance and Financial Position, Location [Table Text Block] Fair value of all derivative instruments held by the Fund Net Realized Gain Loss and Change in Net Unrealized Appreciation Depreciation [Abstract] Recognized on Derivative Instruments Net realized gain (loss) and change in net unrealized appreciation (depreciation) recognized on derivative instruments Net realized gain loss and change in net unrealized appreciation depreciation recognized on derivative instruments . Federal National Mortgage Association [Member] Federal National Mortgage Association [Member] Federal national mortgage association . Short Term Investment Eleven [Member] 7/1/2011 [Member] Short term investment eleven. Management Fee Percentage Management Fee Percentage Management fee percentage. Management Fees Provided for Service [Table] Management fees provided for service. Management Fees Provided for Service [Line Items] Management fees provided for service. Derivative, Fair Value, Net Net Derivative Fair Value Common Stock, Dividends, Per Share, Cash Paid Distributions Major Types of Debt and Equity Securities [Axis] Repurchase Agreements [Member] Repurchase Agreements [Member] Unrealized Appreciation On Futures Contracts Unrealized appreciation on futures contracts, net Unrealized appreciation on futures contract net. Operating Expenses Total expenses U S Government Agencies Debt Securities [Member] U.S. Government and Agency Obligations [Member] Ice Brent Crude Oil Futures Two [Member] ICE Brent Crude Oil Futures 2 [Member] Ice brent crude oil futures. Nymex Gasoline Rbob Futures Two [Member] NYMEX Gasoline Rbob Futures 2 [Member] Nymex gasoline rbob futures. Lme Nickel Futures One [Member] Lme nickel futures. LME Nickel Futures 1 [Member] Lme Nickel Futures Two [Member] Lme nickel futures. LME Nickel Futures 2 [Member] Aggregate Nickel [Member] Total nickel. Aggregate Nickel [Member] Lme Zinc Futures Three [Member] Lme zinc futures. LME Zinc Futures 3 [Member] Lme Lead Futures One [Member] Lme lead futures. LME Lead Futures 1 [Member] Lme Lead Futures Two [Member] Lme lead futures. LME Lead Futures 2 [Member] Aggregate Lead [Member] Total lead. Aggregate Lead [Member] Cbot Soybean Meal Futures One [Member] CBOT Soybean Meal Futures 1 [Member] Cbot soybean meal futures. Aggregate Soybean Meal [Member] Aggregate Soybean Meal [Member] Total soybean meal. Cme Feeder Cattle Futures One [Member] Cme feeder cattle futures. CME Feeder Cattle Futures 1 [Member] Aggregate Feeder Cattle [Member] Aggregate Feeder Cattle [Member] Total feeder cattle. Nymex Heating Oil Futures Two [Member] Nymex heating oil futures. NYMEX Heating Oil Futures 2 [Member] Deposits with brokers for open futures contracts Deposits with brokers Interest Receivable Interest receivable Other Assets Other assets Total assets Total assets Open Option Contracts Written, Premium Call options written, at value (premiums received $1,504,277 and $1,428,047, respectively) Dividends Payable Distributions Net Cash Provided by (Used in) Operating Activities Net cash provided by (used in) operating activities Unrealized Gain (Loss) on Commodity Contracts Futures contracts Futures contracts Future [Member] Futures Contracts [Member] Options Held [Member] Options [Member] Call Options Written [Member] Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value Short-Term Investments, Value Assets Sold under Agreements to Repurchase, Carrying Amount Repurchase Agreements, Principal Amount Assets Sold under Agreements to Repurchase, Interest Rate Repurchase Agreements, Coupon Assets Sold under Agreements to Repurchase, Market Value Repurchase Agreements, Value Open Option Contracts Written, Premiums Outstanding, end of the period, Premiums Received Outstanding, beginning of period, Premiums Received Call options written, at value, premiums received Financial Instruments Owned Us Government And Agency Obligations At Cost Total U.S. Government and Agency Obligations, Cost The cost as of the balance sheet date of firm holdings in debt obligations issued by the US government including short-term Treasury bills, medium-term Treasury notes, and long-term Treasury bonds, as well as debt issued by agencies. Includes both pledged (to counterparties as collateral for financing transactions) and unpledged holdings. Date Of Investment Repurchase Agreement Date of Repurchase Agreement with State Street Bank Date the repurchase agreement was made. Repurchase Price Repurchase price Repurchase price. Collateralized By Us Treasury Notes Collateralized by U.S treasury notes Collateralized by U.S treasury notes. Interest Rate Of Treasury Notes Treasury Notes , Interest rate Interest rate of treasury notes. Maturity Date Of Treasury Notes Maturity date of Treasury Notes Treasury notes maturity date. Cost Of Total Repurchase Agreements Total Repurchase Agreements, Cost Cost of total repurchase agreements. Maturity Value Of Treasury Notes Maturity value of Treasury Notes Maturity value of treasury notes. Derivative Asset, Fair Value, Gross Asset Derivative asset, fair value, gross asset Derivative Asset, Fair Value, Gross Liability Derivative asset, fair value, gross liability Derivative Liability, Fair Value, Gross Asset Derivative liability, fair value, gross asset Derivative Liability, Fair Value, Gross Liability Derivative liability, fair value, gross liability