United States Oil Fund (USO) 10-K 28 Feb 14 2013 FY Annual report Financial data

Document_And_Entity_Informatio

Document And Entity Information (USD $)	12 Months Ended
	Dec. 31, 2013	Feb. 25, 2014	Jun. 30, 2013
Document Information [Line Items]	'	'	'
Document Type	'10-K	'	'
Amendment Flag	'false	'	'
Document Period End Date	31-Dec-13	'	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'
Trading Symbol	'USO	'	'
Entity Common Stock, Shares Outstanding	'	18,200,000	'
Entity Registrant Name	'United States Oil Fund, LP	'	'
Entity Central Index Key	'0001327068	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Well-known Seasoned Issuer	'No	'	'
Entity Voluntary Filers	'No	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Filer Category	'Large Accelerated Filer	'	'
Entity Public Float	'	'	$816,902,000

Statements_of_Financial_Condit

Statements of Financial Condition (USD $)	Dec. 31, 2013	Dec. 31, 2012
Assets	'	'
Cash and cash equivalents (Notes 2 and 5)	$570,875,786	$1,019,006,171
Equity in trading accounts:	'	'
Cash and cash equivalents	20,806,873	154,761,599
Unrealized gain on open commodity futures contracts	2,724,970	67,180,420
Receivable for shares sold	45,801,275	0
Dividend receivable	7,969	20,182
Interest receivable	52	0
Other assets	18,587	380,835
Total assets	640,235,512	1,241,349,207
Liabilities and Partners' Capital	'	'
Payable for shares redeemed	64,385,796	56,390,127
Professional fees payable	1,230,814	1,200,671
General Partner management fees payable (Note 3)	254,721	516,449
License fees payable	31,845	51,035
Brokerage commissions payable	19,661	44,461
Directors' fees payable	35,468	42,976
Other liabilities	153	153
Total liabilities	65,958,458	58,245,872
Partners' Capital	'	'
General Partner	0	0
Limited Partners	574,277,054	1,183,103,335
Total Partners' Capital	574,277,054	1,183,103,335
Total liabilities and partners' capital	$640,235,512	$1,241,349,207
Limited Partners' shares outstanding	16,300,000	35,400,000
Net asset value per share	$35.23	$33.42
Market value per share	$35.32	$33.37

Schedule_of_Investments

Schedule of Investments (USD $)	Dec. 31, 2013		Dec. 31, 2012
Unrealized Gain (Loss) on Open Commodity Contracts	$2,724,970		$67,180,420
Open Futures Contracts, Long [Member]	'		'
Number of Contracts	'		12,886
Unrealized Gain (Loss) on Open Commodity Contracts	'		67,180,420
% of Partners' Capital	'		5.68%
Open Futures Contracts, Long [Member] | Foreign [Member] | ICE WTI Crude Oil Futures February contracts, expiring January [Member]	'		'
Number of Contracts	'		2,000
Unrealized Gain (Loss) on Open Commodity Contracts	'		9,680,000
% of Partners' Capital	'		0.82%
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Crude Oil Futures CL February contracts, expiring January [Member]	'		'
Number of Contracts	5,835	[1]	10,886
Unrealized Gain (Loss) on Open Commodity Contracts	2,724,970	[1]	57,500,420
% of Partners' Capital	0.47%	[1]	4.86%
Cash Equivalent [Member]	'		'
Market Value	508,872,583		965,890,925
% of Partners' Capital	88.61%		81.64%
Cash Equivalent [Member] | United States [Member] | Us Treasury Bills, 0.07%, 3/27/2014 [Member]	'		'
Principal Amount	100,000,000		'
Market Value	99,983,472		'
% of Partners' Capital	17.41%		'
Cash Equivalent [Member] | United States [Member] | Us Treasury Bills, 0.08%, 4/24/2014 [Member]	'		'
Principal Amount	100,000,000		'
Market Value	99,974,889		'
% of Partners' Capital	17.41%		'
Cash Equivalent [Member] | United States [Member] | US Treasury Securities [Member]	'		'
Market Value	199,958,361		219,976,704
% of Partners' Capital	34.82%		18.59%
Cash Equivalent [Member] | United States [Member] | US Treasury Securities [Member] | Us Treasury Bills, 0.10%, 1/17/2013 [Member]	'		'
Principal Amount	'		120,000,000
Market Value	'		119,994,933
% of Partners' Capital	'		10.14%
Cash Equivalent [Member] | United States [Member] | US Treasury Securities [Member] | Us Treasury Bills, 0.05%, 5/02/2013 [Member]	'		'
Principal Amount	'		100,000,000
Market Value	'		99,981,771
% of Partners' Capital	'		8.45%
Cash Equivalent [Member] | United States [Member] | Money Market Funds [Member]	'		'
Market Value	308,914,222		745,914,221
% of Partners' Capital	53.79%		63.05%
Cash Equivalent [Member] | United States [Member] | Money Market Funds [Member] | Fidelity Institutional Government Portfolio, Class I [Member]	'		'
Principal Amount	53,628		137,053,627
Market Value	53,628		137,053,627
% of Partners' Capital	0.01%		11.59%
Cash Equivalent [Member] | United States [Member] | Money Market Funds [Member] | Goldman Sachs Financial Square Funds Government Fund Class FS [Member]	'		'
Principal Amount	7,792,941		207,792,941
Market Value	7,792,941		207,792,941
% of Partners' Capital	1.36%		17.56%
Cash Equivalent [Member] | United States [Member] | Money Market Funds [Member] | Morgan Stanley Institutional Liquidity Fund, Government Portfolio [Member]	'		'
Principal Amount	201,057,695		201,057,695
Market Value	201,057,695		201,057,695
% of Partners' Capital	35.01%		16.99%
Cash Equivalent [Member] | United States [Member] | Money Market Funds [Member] | Wells Fargo Advantage Government Money Market Fund Class I [Member]	'		'
Principal Amount	100,009,958		200,009,958
Market Value	$100,009,958		$200,009,958
% of Partners' Capital	17.41%		16.91%
[1]	Collateral amounted to $20,806,873 on open futures contracts.

Schedule_of_Investments_Parent

Schedule of Investments (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Collateral Amount On Open Futures Contracts	20,806,873	67,180,420
Foreign [Member] | NYMEX Crude Oil Futures CL February contracts, expiring January [Member] | Open Futures Contracts, Long [Member]	'	'
Expiration date	'	'January 2013
Foreign [Member] | ICE WTI Crude Oil Futures February contracts, expiring January [Member] | Open Futures Contracts, Long [Member]	'	'
Expiration date	'January 2014	'January 2013
United States [Member] | U.S. Treasury Bill, 0.10%, 1/17/2013 [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]	'	'
Interest rate	'	0.10%
Expiration date	'	'1/17/2013
United States [Member] | U.S. Treasury Bill, 0.05%, 5/02/2013 [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]	'	'
Interest rate	'	0.05%
Expiration date	'	'5/02/2013
United States [Member] | Us Treasury Bills , 0.07%, 3/27/2014 [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]	'	'
Interest rate	0.07%	'
Expiration date	'3/27/2014	'
United States [Member] | Us Treasury Bills, 0.08%, 4/24/2014 [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]	'	'
Interest rate	0.08%	'
Expiration date	'4/24/2014	'

Statements_of_Operations

Statements of Operations (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Gain (loss) on trading of commodity futures contracts:	'	'	'
Realized gain (loss) on closed positions	$144,592,660	($196,807,460)	$201,717,550
Change in unrealized gain (loss) on open positions	-64,455,450	73,652,730	-50,432,650
Dividend income	130,166	221,143	193,961
Interest income	166,245	176,231	72,005
Other income	261,000	190,000	279,000
Total income (loss)	80,694,621	-122,567,356	151,829,866
Expenses	'	'	'
General Partner management fees (Note 3)	3,981,890	5,751,949	6,761,103
Professional fees	1,088,401	1,299,277	881,228
Brokerage commissions	965,576	1,298,827	1,529,433
License fees	132,730	191,732	353,950
Registration fees	362,265	176,971	47,450
Directors' fees	107,851	132,405	120,905
Other expenses	88,352	103,875	109,999
Total expenses	6,727,065	8,955,036	9,804,068
Net income (loss)	$73,967,556	($131,522,392)	$142,025,798
Net income (loss) per limited partnership share	$1.81	($4.65)	($0.90)
Net income (loss) per weighted average limited partnership share	$2.92	($3.62)	$3.57
Weighted average limited partnership shares outstanding	25,330,685	36,296,721	39,764,384

Statements_of_Changes_in_Partn

Statements of Changes in Partners' Capital (USD $)	Total	General Partner [Member]	Limited Partners [Member]
Beginning Balances at Dec. 31, 2010	$1,788,607,572	$0	$1,788,607,572
Net asset value, beginning of year at Dec. 31, 2010	$38.97	'	'
Addition of 124,700,000 in 2013, 100,100,000 in 2012 and 138,300,000 in 2011 partnership units	5,159,411,628	0	5,159,411,628
Redemption of 143,800,000 in 2013, 93,800,000 in 2012 and 155,100,000 in 2011 partnership units	-5,982,086,116	0	-5,982,086,116
Net income (loss)	142,025,798	0	142,025,798
Ending Balances at Dec. 31, 2011	1,107,958,882	0	1,107,958,882
Net asset value, end of year at Dec. 31, 2011	$38.07	'	'
Addition of 124,700,000 in 2013, 100,100,000 in 2012 and 138,300,000 in 2011 partnership units	3,503,707,052	0	3,503,707,052
Redemption of 143,800,000 in 2013, 93,800,000 in 2012 and 155,100,000 in 2011 partnership units	-3,297,040,207	0	-3,297,040,207
Net income (loss)	-131,522,392	0	-131,522,392
Ending Balances at Dec. 31, 2012	1,183,103,335	0	1,183,103,335
Net asset value, end of year at Dec. 31, 2012	$33.42	'	'
Addition of 124,700,000 in 2013, 100,100,000 in 2012 and 138,300,000 in 2011 partnership units	4,397,936,880	0	4,397,936,880
Redemption of 143,800,000 in 2013, 93,800,000 in 2012 and 155,100,000 in 2011 partnership units	-5,080,730,717	0	-5,080,730,717
Net income (loss)	73,967,556	0	73,967,556
Ending Balances at Dec. 31, 2013	$574,277,054	$0	$574,277,054
Net asset value, end of year at Dec. 31, 2013	$35.23	'	'

Statements_of_Changes_in_Partn1

Statements of Changes in Partners' Capital (Parenthetical)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Addition of partnership units	124,700,000	100,100,000	138,300,000
Redemption of partnership units	143,800,000	93,800,000	155,100,000

Statements_of_Cash_Flows

Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash Flows from Operating Activities:	'	'	'
Net income (loss)	$73,967,556	($131,522,392)	$142,025,798
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:	'	'	'
(Increase) decrease in commodity futures trading account - cash and cash equivalents	133,954,726	148,904,382	-49,162,371
Unrealized (gain) loss on futures contracts	64,455,450	-73,652,730	50,432,650
(Increase) decrease in dividend receivable	12,213	-9,523	38,126
(Increase) decrease in interest receivable	-52	202	-202
Decrease in other assets	362,248	126,062	66,609
Increase (decrease) in investment payable	0	-553	553
Increase (decrease) in professional fees payable	30,143	63,064	-209,823
Increase (decrease) in General Partner management fees payable	-261,728	70,734	-252,602
Decrease in license fees payable	-19,190	-3,664	-56,539
Increase (decrease) in brokerage commissions payable	-24,800	12,275	-27,000
Increase (decrease) in directors' fees payable	-7,508	4,564	-5,050
Increase in other liabilities	0	0	153
Net cash provided by (used in) operating activities	272,469,058	-56,007,579	142,850,302
Cash Flows from Financing Activities:	'	'	'
Addition of partnership shares	4,352,135,605	3,541,781,282	5,121,337,398
Redemption of partnership shares	-5,072,735,048	-3,305,376,271	-5,948,534,053
Net cash provided by (used in) financing activities	-720,599,443	236,405,011	-827,196,655
Net Increase (Decrease) in Cash and Cash Equivalents	-448,130,385	180,397,432	-684,346,353
Cash and Cash Equivalents, beginning of year	1,019,006,171	838,608,739	1,522,955,092
Cash and Cash Equivalents, end of year	$570,875,786	$1,019,006,171	$838,608,739

Organization_and_Business

Organization and Business	12 Months Ended
	Dec. 31, 2013
Organization and Business	'
	NOTE 1 - ORGANIZATION AND BUSINESS
	The United States Oil Fund, LP (“USO”) was organized as a limited partnership under the laws of the state of Delaware on May 12, 2005. USO is a commodity pool that issues limited partnership shares (“shares”) that may be purchased and sold on the NYSE Arca, Inc. (the “NYSE Arca”). Prior to November 25, 2008, USO’s shares traded on the American Stock Exchange (the “AMEX”). USO will continue in perpetuity, unless terminated sooner upon the occurrence of one or more events as described in its Sixth Amended and Restated Agreement of Limited Partnership dated as of March 1, 2013 (the “LP Agreement”). The investment objective of USO is for the daily changes in percentage terms of its shares’ per share net asset value (“NAV”) to reflect the daily changes in percentage terms of the spot price of light, sweet crude oil delivered to Cushing, Oklahoma, as measured by the daily changes in the price of the futures contract for light, sweet crude oil traded on the New York Mercantile Exchange (the “NYMEX”) that is the near month contract to expire, except when the near month contract is within two weeks of expiration, in which case the futures contract will be the next month contract to expire (the “Benchmark Oil Futures Contract”), less USO’s expenses. It is not the intent of USO to be operated in a fashion such that the per share NAV will equal, in dollar terms, the spot price of light, sweet crude oil or any particular futures contract based on light, sweet crude oil. It is not the intent of USO to be operated in a fashion such that its per share NAV will reflect the percentage change of the price of any particular futures contract as measured over a time period greater than one day. United States Commodity Funds LLC (“USCF”), the general partner of USO, believes that it is not practical to manage the portfolio to achieve such an investment goal when investing in Oil Futures Contracts (as defined below) and Other Oil-Related Investments (as defined below). USO accomplishes its objective through investments in futures contracts for light, sweet crude oil, and other types of crude oil, diesel-heating oil, gasoline, natural gas and other petroleum-based fuels that are traded on the NYMEX, ICE Futures or other U.S. and foreign exchanges (collectively, “Oil Futures Contracts”) and other oil related investments such as cash-settled options on Oil Futures Contracts, forward contracts for oil, cleared swap contracts and over-the-counter transactions that are based on the price of crude oil, diesel-heating oil, gasoline, natural gas and other petroleum-based fuels, Oil Futures Contracts and indices based on the foregoing (collectively, “Other Oil-Related Investments”). As of December 31, 2013, USO held 5,835 Oil Futures Contracts for light, sweet crude oil traded on the NYMEX and did not hold any Oil Futures Contracts for light, sweet crude oil traded on the ICE Futures.
	USO commenced investment operations on April 10, 2006 and has a fiscal year ending on December 31. USCF is responsible for the management of USO. USCF is a member of the National Futures Association (the “NFA”) and became a commodity pool operator registered with the Commodity Futures Trading Commission (the “CFTC”) effective December 1, 2005. USCF is also the general partner of the United States Natural Gas Fund, LP (“UNG”), the United States 12 Month Oil Fund, LP (“USL”), the United States Gasoline Fund, LP (“UGA”) and the United States Diesel-Heating Oil Fund, LP (“UHN”), which listed their limited partnership shares on the AMEX under the ticker symbols “UNG” on April 18, 2007, “USL” on December 6, 2007, “UGA” on February 26, 2008 and “UHN” on April 9, 2008, respectively. As a result of the acquisition of the AMEX by NYSE Euronext, each of UNG’s, USL’s, UGA’s and UHN’s shares commenced trading on the NYSE Arca on November 25, 2008. USCF is also the general partner of the United States Short Oil Fund, LP (“DNO”), the United States 12 Month Natural Gas Fund, LP (“UNL”) and the United States Brent Oil Fund, LP (“BNO”), which listed their limited partnership shares on the NYSE Arca under the ticker symbols “DNO” on September 24, 2009, “UNL” on November 18, 2009 and “BNO” on June 2, 2010, respectively. USCF is also the sponsor of the United States Commodity Index Fund (“USCI”), the United States Copper Index Fund (“CPER”), the United States Agriculture Index Fund (“USAG”) and the United States Metals Index Fund (“USMI”), each a series of the United States Commodity Index Funds Trust. USCI, CPER, USAG and USMI listed their shares on the NYSE Arca under the ticker symbol “USCI” on August 10, 2010, “CPER” on November 15, 2011, “USAG” on April 13, 2012 and “USMI” on June 19, 2012, respectively. All funds listed previously are referred to collectively herein as the “Related Public Funds.”  USCF previously filed registration statements to register shares of the United States Sugar Fund (“USSF”), the United States Natural Gas Double Inverse Fund (“UNGD”), the United States Gasoil Fund (“USGO”) and the United States Asian Commodities Basket Fund (“UAC”), each of which is a series of the United States Commodity Funds Trust I, and the US Golden Currency Fund (“HARD”), a series of the United States Currency Funds Trust.  On December 30, 2013, USCF withdrew the registration statements for USSF, UNGD, USGO and UAC effective December 31, 2013.  On January 27, 2014, USCF withdrew the registration statement for HARD.  HARD was never available to the public and at the time of withdrawal, HARD was still in the process of review by various regulatory agencies which have regulatory authority over USCF and HARD.
	USO issues shares to certain authorized purchasers (“Authorized Purchasers”) by offering baskets consisting of 100,000 shares (“Creation Baskets”) through ALPS Distributors, Inc., as the marketing agent (the “Marketing Agent”). The purchase price for a Creation Basket is based upon the NAV of a share calculated shortly after the close of the core trading session on the NYSE Arca on the day the order to create the basket is properly received.
	In addition, Authorized Purchasers pay USO a $1,000 fee for each order placed to create one or more Creation Baskets or to redeem one or more baskets (“Redemption Baskets”), consisting of 100,000 shares. Shares may be purchased or sold on a nationally recognized securities exchange in smaller increments than a Creation Basket or Redemption Basket. Shares purchased or sold on a nationally recognized securities exchange are not purchased or sold at the per share NAV of USO but rather at market prices quoted on such exchange.
	In April 2006, USO initially registered 17,000,000 shares on Form S-1 with the U.S. Securities and Exchange Commission (the “SEC”). On April 10, 2006, USO listed its shares on the AMEX under the ticker symbol “USO”. On that day, USO established its initial per share NAV by setting the price at $67.39 and issued 200,000 shares in exchange for $13,479,000. USO also commenced investment operations on April 10, 2006, by purchasing Oil Futures Contracts traded on the NYMEX based on light, sweet crude oil. As of December 31, 2013, USO had registered a total of 1,627,000,000 shares.

Summary_Of_Significant_Account

Summary Of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2013
Summary Of Significant Accounting Policies	'
	NOTE 2 - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
	Revenue Recognition
	Commodity futures contracts, forward contracts, physical commodities, and related options are recorded on the trade date. All such transactions are recorded on the identified cost basis and marked to market daily. Unrealized gains or losses on open contracts are reflected in the statements of financial condition and represent the difference between the original contract amount and the market value (as determined by exchange settlement prices for futures contracts and related options and cash dealer prices at a predetermined time for forward contracts, physical commodities, and their related options) as of the last business day of the year or as of the last date of the financial statements. Changes in the unrealized gains or losses between periods are reflected in the statements of operations. USO earns interest on its assets denominated in U.S. dollars on deposit with the futures commission merchant at the overnight Federal Funds Rate less 32 basis points. In addition, USO earns income on funds held at the custodian or futures commission merchant at prevailing market rates earned on such investments.
	Brokerage Commissions
	Brokerage commissions on all open commodity futures contracts are accrued on a full-turn basis.
	Income Taxes
	USO is not subject to federal income taxes; each partner reports his/her allocable share of income, gain, loss deductions or credits on his/her own income tax return.
	In accordance with accounting principles generally accepted in the United States of America (“GAAP”), USO is required to determine whether a tax position is more likely than not to be sustained upon examination by the applicable taxing authority, including resolution of any tax related appeals or litigation processes, based on the technical merits of the position. USO files an income tax return in the U.S. federal jurisdiction, and may file income tax returns in various U.S. states. USO is not subject to income tax return examinations by major taxing authorities for years before 2010. The tax benefit recognized is measured as the largest amount of benefit that has a greater than fifty percent likelihood of being realized upon ultimate settlement. De-recognition of a tax benefit previously recognized results in USO recording a tax liability that reduces net assets. However, USO’s conclusions regarding this policy may be subject to review and adjustment at a later date based on factors including, but not limited to, on-going analysis of and changes to tax laws, regulations and interpretations thereof. USO recognizes interest accrued related to unrecognized tax benefits and penalties related to unrecognized tax benefits in income tax fees payable, if assessed. No interest expense or penalties have been recognized as of and for the year ended December 31, 2013.
	Creations and Redemptions
	Authorized Purchasers may purchase Creation Baskets or redeem Redemption Baskets only in blocks of 100,000 shares at a price equal to the NAV of the shares calculated shortly after the close of the core trading session on the NYSE Arca on the day the order is placed.
	USO receives or pays the proceeds from shares sold or redeemed within three business days after the trade date of the purchase or redemption. The amounts due from Authorized Purchasers are reflected in USO’s statements of financial condition as receivable for shares sold, and amounts payable to Authorized Purchasers upon redemption are reflected as payable for shares redeemed.
	Partnership Capital and Allocation of Partnership Income and Losses
	Profit or loss shall be allocated among the partners of USO in proportion to the number of shares each partner holds as of the close of each month. USCF may revise, alter or otherwise modify this method of allocation as described in the LP Agreement.
	Calculation of Per Share Net Asset Value
	USO’s per share NAV is calculated on each NYSE Arca trading day by taking the current market value of its total assets, subtracting any liabilities and dividing that amount by the total number of shares outstanding. USO uses the closing price for the contracts on the relevant exchange on that day to determine the value of contracts held on such exchange.
	Net Income (Loss) Per Share
	Net income (loss) per share is the difference between the per share NAV at the beginning of each period and at the end of each period. The weighted average number of shares outstanding was computed for purposes of disclosing net income (loss) per weighted average share. The weighted average shares are equal to the number of shares outstanding at the end of the period, adjusted proportionately for shares added and redeemed based on the amount of time the shares were outstanding during such period. There were no shares held by USCF at December 31, 2013.
	Offering Costs
	Offering costs incurred in connection with the registration of additional shares after the initial registration of shares are borne by USO. These costs include registration fees paid to regulatory agencies and all legal, accounting, printing and other expenses associated with such offerings. These costs are accounted for as a deferred charge and thereafter amortized to expense over twelve months on a straight-line basis or a shorter period if warranted.
	Cash Equivalents
	Cash equivalents include money market funds and overnight deposits or time deposits with original maturity dates of six months or less.
	Reclassification
	Certain amounts in the accompanying financial statements were reclassified to conform to the current presentation.
	Use of Estimates
	The preparation of financial statements in conformity with GAAP requires USCF to make estimates and assumptions that affect the reported amount of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of the revenue and expenses during the reporting period. Actual results may differ from those estimates and assumptions.

Fees_Paid_By_The_Fund_And_Rela

Fees Paid By The Fund And Related Party Transactions	12 Months Ended
	Dec. 31, 2013
Fees Paid By The Fund And Related Party Transactions	'
	NOTE 3 - FEES PAID BY THE FUND AND RELATED PARTY TRANSACTIONS
	USCF Management Fee
	Under the LP Agreement, USCF is responsible for investing the assets of USO in accordance with the objectives and policies of USO. In addition, USCF has arranged for one or more third parties to provide administrative, custody, accounting, transfer agency and other necessary services to USO. For these services, USO is contractually obligated to pay USCF a fee, which is paid monthly, equal to 0.45% per annum of average daily total net assets.
	Ongoing Registration Fees and Other Offering Expenses
	USO pays all costs and expenses associated with the ongoing registration of its shares subsequent to the initial offering. These costs include registration or other fees paid to regulatory agencies in connection with the offer and sale of shares, and all legal, accounting, printing and other expenses associated with such offer and sale. For the years ended December 31, 2013, 2012 and 2011, USO incurred $362,265, $176,971 and $47,450, respectively, in registration fees and other offering expenses.
	Directors’ Fees and Expenses
	USO is responsible for paying its portion of the directors’ and officers’ liability insurance for USO and the Related Public Funds and the fees and expenses of the independent directors who also serve as audit committee members of USO and the Related Public Funds organized as limited partnerships and, as of July 8, 2011, the Related Public Funds organized as a series of a Delaware statutory trust. USO shares the fees and expenses on a pro rata basis with each Related Public Fund, as described above, based on the relative assets of each fund computed on a daily basis. These fees and expenses for the year ended December 31, 2013 were $555,465 for USO and the Related Public Funds. USO’s portion of such fees and expenses for the year ended December 31, 2013 was $195,352. For the year ended December 31, 2012, these fees and expenses were $540,586 for USO and the Related Public Funds. USO’s portion of such fees and expenses for the year ended December 31, 2012 was $235,481. For the year ended December 31, 2011, these fees and expenses were $607,582 for USO and the Related Public Funds. USO’s portion of such fees and expenses for the year ended December 31, 2011 was $229,954. Effective as of April 1, 2010, USO became responsible for paying its portion of any payments that may become due to the independent directors pursuant to the deferred compensation agreements entered into between the independent directors, USCF, USO and the Related Public Funds, except USCI, CPER, USAG and USMI.
	Licensing Fees
	As discussed in Note 4 below, USO entered into a licensing agreement with the NYMEX on April 10, 2006, as amended on October 20, 2011. Pursuant to the agreement, through October 19, 2011, USO and the Related Public Funds, other than BNO, USCI, CPER, USAG and USMI, paid a licensing fee that was equal to 0.04% for the first $1,000,000,000 of combined net assets of the funds and 0.02% for combined net assets above $1,000,000,000. On and after October 20, 2011, USO and the Related Public Funds, other than BNO, USCI, CPER, USAG and USMI, pay a licensing fee that is equal to 0.015% on all net assets. During the years ended December 31, 2013, 2012 and 2011, USO incurred $132,730, $191,732 and $353,950, respectively, under this arrangement.
	Investor Tax Reporting Cost
	The fees and expenses associated with USO’s audit expenses and tax accounting and reporting requirements are paid by USO. These costs were approximately $1,000,000 for the each of the year ended December 31, 2013, approximately $1,000,000 for the year ended December 31, 2012 and approximately $1,200,000 for the year ended December 31, 2011.
	Other Expenses and Fees
	In addition to the fees described above, USO pays all brokerage fees and other expenses in connection with the operation of USO, excluding costs and expenses paid by USCF as outlined in Note 4 below.

Contracts_And_Agreements

Contracts And Agreements	12 Months Ended
	Dec. 31, 2013
Contracts And Agreements	'
	NOTE 4 - CONTRACTS AND AGREEMENTS
	USO is party to a marketing agent agreement, dated as of March 13, 2006, as amended from time to time, with the Marketing Agent and USCF, whereby the Marketing Agent provides certain marketing services for USO as outlined in the agreement. The fees of the Marketing Agent, which are borne by USCF, include a marketing fee of $425,000 per annum plus the following incentive fee: 0.00% on USO’s assets from $0 - $500 million; 0.04% on USO’s assets from $500 million - $4 billion; and 0.03% on USO’s assets in excess of $4 billion.
	The above fees do not include the following expenses, which are also borne by USCF: the cost of placing advertisements in various periodicals; website construction and development; or the printing and production of various marketing materials.
	USO is also party to a custodian agreement, dated March 13, 2006, as amended from time to time, with Brown Brothers Harriman & Co. (“BBH&Co.”) and USCF, whereby BBH&Co. holds investments on behalf of USO. USCF pays the fees of the custodian, which are determined by the parties from time to time. In addition, USO is party to an administrative agency agreement, dated March 13, 2006, as amended from time to time, with USCF and BBH&Co., whereby BBH&Co. acts as the administrative agent, transfer agent and registrar for USO. USCF also pays the fees of BBH&Co. for its services under such agreement and such fees are determined by the parties from time to time.
	Currently, USCF pays BBH&Co. for its services, in the foregoing capacities, a minimum amount of $75,000 annually for its custody, fund accounting and fund administration services rendered to USO and each of the Related Public Funds, as well as a $20,000 annual fee for its transfer agency services. In addition, USCF pays BBH&Co. an asset-based charge of (a)  0.06% for the first $500 million of the Related Public Funds’ combined net assets, (b)  0.0465% for the Related Public Funds’ combined net assets greater than $500 million but less than $1 billion, and (c)  0.035% once the Related Public Funds’ combined net assets exceed $1 billion. The annual minimum amount will not apply if the asset-based charge for all accounts in the aggregate exceeds $75,000. USCF also pays transaction fees ranging from $7 to $15 per transaction.
	On October 8, 2013, USO entered into a brokerage agreement with RBC Capital Markets, LLC (“RBC Capital” or “RBC”) to serve as USO’s futures commission merchant (“FCM”), effective October 10, 2013.  Prior to October 10, 2013, the FCM was UBS Securities LLC (“UBS Securities”). The agreements require RBC Capital and UBS Securities to provide services to USO in connection with the purchase and sale of Oil Futures Contracts and Other Oil-Related Investments that may be purchased and sold by or through RBC Capital and/or UBS Securities for USO’s account. In accordance with each agreement, RBC Capital and UBS Securities charge USO commissions of approximately $7 to $15 per round-turn trade, including applicable exchange and NFA fees for Oil Futures Contracts and options on Oil Futures Contracts. Such fees include those incurred when purchasing Oil Futures Contracts and options on Oil Futures Contracts when USO issues shares as a result of a Creation Basket, as well as fees incurred when selling Oil Futures Contracts and options on Oil Futures Contracts when USO redeems shares as a result of a Redemption Basket. Such fees are also incurred when Oil Futures Contracts and options on Oil Futures Contracts are purchased or redeemed for the purpose of rebalancing the portfolio. USO also incurs commissions to brokers for the purchase and sale of Oil Futures Contracts, Other Oil-Related Investments or short-term obligations of the United States of two years or less (“Treasuries”). During the year ended December 31, 2013, total commissions accrued to brokers amounted to $965,576. Of this amount, approximately $697,519, or 72.34%, was a result of rebalancing costs and approximately $267,057, or 27.66%, was the result of trades necessitated by creation and redemption activity. By comparison, during the year ended December 31, 2012, total commissions accrued to brokers amounted to $1,298,827. Of this amount, approximately $1,061,305, or 81.71%, was a result of rebalancing costs and approximately $237,522, or 18.29%, was the result of trades necessitated by creation and redemption activity. By comparison, during the year ended December 31, 2011, total commissions accrued to brokers amounted to $1,529,433. Of this amount, approximately $1,148,618, or 75.10%, was a result of rebalancing costs and approximately $380,815, or 24.90%, was the result of trades necessitated by creation and redemption activity. The decrease in the total commissions accrued to brokers for the year ended December 31, 2013 as compared to the year ended December 31, 2012, was primarily a result of the decrease in USO’s smaller size during the year ended December 31, 2013, as compared to the year ended December 31, 2012. The decrease in the total commissions accrued to brokers for the year ended December 31, 2012 as compared to the year ended December 31, 2011, was primarily a result of the decrease in USO’s average total net assets during the year ended December 31, 2012, as compared to the year ended December 31, 2011. As an annualized percentage of average total net assets, the figure for the year ended December 31, 2013 represents approximately 0.11% of average total net assets. By comparison, the figure for the year ended December 31, 2012 represented approximately 0.10% of average total net assets and the figure for the year ended December 31, 2011 represented approximately 0.10% of average total net assets. However, there can be no assurance that commission costs and portfolio turnover will not cause commission expenses to rise in future quarters.
	USO and the NYMEX entered into a licensing agreement on April 10, 2006, as amended on October 20, 2011, whereby USO was granted a non-exclusive license to use certain of the NYMEX’s settlement prices and service marks. Under the licensing agreement, USO and the Related Public Funds, other than BNO, USCI, CPER, USAG and USMI, pay the NYMEX an asset-based fee for the license, the terms of which are described in Note 3. USO expressly disclaims any association with the NYMEX or endorsement of USO by the NYMEX and acknowledges that “NYMEX” and “New York Mercantile Exchange” are registered trademarks of the NYMEX.

Financial_Instruments_OffBalan

Financial Instruments, Off-Balance Sheet Risks and Contingencies	12 Months Ended
	Dec. 31, 2013
Financial Instruments, Off-Balance Sheet Risks and Contingencies	'
	NOTE 5 - FINANCIAL INSTRUMENTS, OFF-BALANCE SHEET RISKS AND CONTINGENCIES
	USO engages in the trading of futures contracts, options on futures contracts and cleared swaps (collectively, “derivatives”). USO is exposed to both market risk, which is the risk arising from changes in the market value of the contracts, and credit risk, which is the risk of failure by another party to perform according to the terms of a contract.
	USO may enter into futures contracts, options on futures contracts and cleared swaps to gain exposure to changes in the value of an underlying commodity. A futures contract obligates the seller to deliver (and the purchaser to accept) the future delivery of a specified quantity and type of a commodity at a specified time and place. Some futures contracts may call for physical delivery of the asset, while others are settled in cash. The contractual obligations of a buyer or seller may generally be satisfied by taking or making physical delivery of the underlying commodity or by making an offsetting sale or purchase of an identical futures contract on the same or linked exchange before the designated date of delivery.
	The purchase and sale of futures contracts, options on futures contracts and cleared swaps require margin deposits with a futures commission merchant. Additional deposits may be necessary for any loss on contract value. The Commodity Exchange Act requires a futures commission merchant to segregate all customer transactions and assets from the futures commission merchant’s proprietary activities.
	Futures contracts and cleared swaps involve, to varying degrees, elements of market risk (specifically commodity price risk) and exposure to loss in excess of the amount of variation margin. The face or contract amounts reflect the extent of the total exposure USO has in the particular classes of instruments. Additional risks associated with the use of futures contracts are an imperfect correlation between movements in the price of the futures contracts and the market value of the underlying securities and the possibility of an illiquid market for a futures contract.
	All of the futures contracts held by USO were exchange-traded through December 31, 2013. The risks associated with exchange-traded contracts are generally perceived to be less than those associated with over-the-counter transactions since, in over-the-counter transactions, a party must rely solely on the credit of its respective individual counterparties. When USO enters into non-exchange traded contracts (including Exchange for Risk or EFR transactions), it is subject to the credit risk associated with counterparty non-performance. The credit risk from counterparty non-performance associated with such instruments is the net unrealized gain, if any, on the transaction. USO has credit risk under its futures contracts since the sole counterparty to all domestic and foreign futures contracts is the clearinghouse for the exchange on which the relevant contracts are traded. In addition, USO bears the risk of financial failure by the clearing broker.
	USO’s cash and other property, such as Treasuries, deposited with a futures commission merchant are considered commingled with all other customer funds, subject to the futures commission merchant’s segregation requirements. In the event of a futures commission merchant’s insolvency, recovery may be limited to a pro rata share of segregated funds available. It is possible that the recovered amount could be less than the total of cash and other property deposited. The insolvency of a futures commission merchant could result in the complete loss of USO’s assets posted with that futures commission merchant; however, the majority of USO’s assets are held in cash and/or cash equivalents with USO’s custodian and would not be impacted by the insolvency of a futures commission merchant. The failure or insolvency of USO’s custodian, however, could result in a substantial loss of USO’s assets.
	USCF invests a portion of USO’s cash in money market funds that seek to maintain a stable per share NAV. USO is exposed to any risk of loss associated with an investment in such money market funds. As of December 31, 2013 and December 31, 2012, USO held investments in money market funds in the amounts of $308,914,222 and $745,914,221, respectively. USO also holds cash deposits with its custodian. Pursuant to a written agreement with BBH&Co., uninvested overnight cash balances are swept to offshore branches of U.S. regulated and domiciled banks located in Toronto, Canada, London, United Kingdom, Grand Cayman, Cayman Islands and Nassau, Bahamas, which are subject to U.S. regulation and regulatory oversight. As of December 31, 2013 and December 31, 2012, USO held cash deposits and investments in Treasuries in the amounts of $282,768,437 and $427,853,549, respectively, with the custodian and futures commission merchant. Some or all of these amounts may be subject to loss should USO’s custodian and/or futures commission merchant cease operations.
	For derivatives, risks arise from changes in the market value of the contracts. Theoretically, USO is exposed to market risk equal to the value of futures contracts purchased and unlimited liability on such contracts sold short. As both a buyer and a seller of options, USO pays or receives a premium at the outset and then bears the risk of unfavorable changes in the price of the contract underlying the option.
	USO’s policy is to continuously monitor its exposure to market and counterparty risk through the use of a variety of financial, position and credit exposure reporting controls and procedures. In addition, USO has a policy of requiring review of the credit standing of each broker or counterparty with which it conducts business.
	The financial instruments held by USO are reported in its statements of financial condition at market or fair value, or at carrying amounts that approximate fair value, because of their highly liquid nature and short-term maturity.

Financial_Highlights

Financial Highlights	12 Months Ended
	Dec. 31, 2013
Financial Highlights	'
	NOTE 6 - FINANCIAL HIGHLIGHTS
	The following table presents per share performance data and other supplemental financial data for the years ended December 31, 2013, 2012 and 2011. This information has been derived from information presented in the financial statements.
		Year ended			Year ended			Year ended
		December 31,			December 31,			December 31,
		2013			2012			2011
	Per Share Operating Performance:
	Net asset value, beginning of year	$	33.42		$	38.07		$	38.97
	Total income (loss)		2.08			-4.4			-0.65
	Total expenses		-0.27			-0.25			-0.25
	Net increase (decrease) in net		1.81			-4.65			-0.9
	asset value
	Net asset value, end of year	$	35.23		$	33.42		$	38.07
	Total Return		5.42	%		-12.21	%		-2.31	%
	Ratios to Average Net Assets
	Total income (loss)		9.12	%		-9.59	%		10.1	%
	Expenses excluding management		0.31	%		0.25	%		0.2	%
	fees
	Management fees		0.45	%		0.45	%		0.45	%
	Net income (loss)		8.36	%		-10.29	%		9.45	%
	Total returns are calculated based on the change in value during the period. An individual shareholder’s total return and ratio may vary from the above total returns and ratios based on the timing of contributions to and withdrawals from USO.

Quarterly_Financial_Data_Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2013
Quarterly Financial Data (Unaudited)	'
	NOTE 7 - QUARTERLY FINANCIAL DATA (Unaudited)
	The following summarized (unaudited) quarterly financial information presents the results of operations and other data for three-month periods ended March 31, June 30, September 30 and December 31, 2013 and 2012.
		First		Second		Third		Fourth
		Quarter		Quarter		Quarter		Quarter
		2013		2013		2013		2013
	Total Income (Loss)	$	47,034,622	$	-5,519,969	$	66,272,544	$	-27,092,576
	Total Expenses		1,949,051		1,788,322		1,572,691		1,417,001
	Net Income (Loss)	$	45,085,571	$	-7,308,291	$	64,699,853	$	-28,509,577
	Net Income (Loss) per Share	$	1.37	$	-0.59	$	2.66	$	-1.63
		First		Second		Third		Fourth
		Quarter		Quarter		Quarter		Quarter
		2012		2012		2012		2012
	Total Income (Loss)	$	40,983,839	$	-227,301,113	$	808,817,737	$	-17,067,819
	Total Expenses		2,243,468		2,172,632		2,223,828		2,315,108
	Net Income (Loss)	$	38,740,371	$	-229,473,745	$	78,593,909	$	-19,382,927
	Net Income (Loss) per Share	$	1.14	$	-7.32	$	2.29	$	-0.76

Fair_Value_Of_Financial_Instru

Fair Value Of Financial Instruments

12 Months Ended

Dec. 31, 2013

Fair Value Of Financial Instruments

'

NOTE 8 - FAIR VALUE OF FINANCIAL INSTRUMENTS

USO values its investments in accordance with Accounting Standards Codification 820 – Fair Value Measurements and Disclosures (“ASC 820”). ASC 820 defines fair value, establishes a framework for measuring fair value in generally accepted accounting principles, and expands disclosures about fair value measurement. The changes to past practice resulting from the application of ASC 820 relate to the definition of fair value, the methods used to measure fair value, and the expanded disclosures about fair value measurement. ASC 820 establishes a fair value hierarchy that distinguishes between: (1) market participant assumptions developed based on market data obtained from sources independent of USO (observable inputs) and (2) USO’s own assumptions about market participant assumptions developed based on the best information available under the circumstances (unobservable inputs). The three levels defined by the ASC 820 hierarchy are as follows:

Level I – Quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity has the ability to access at the measurement date.

Level II – Inputs other than quoted prices included within Level I that are observable for the asset or liability, either directly or indirectly. Level II assets include the following: quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability, and inputs that are derived principally from or corroborated by observable market data by correlation or other means (market-corroborated inputs).

Level III – Unobservable pricing input at the measurement date for the asset or liability. Unobservable inputs shall be used to measure fair value to the extent that observable inputs are not available.

In some instances, the inputs used to measure fair value might fall within different levels of the fair value hierarchy. The level in the fair value hierarchy within which the fair value measurement in its entirety falls shall be determined based on the lowest input level that is significant to the fair value measurement in its entirety.

The following table summarizes the valuation of USO’s securities at December 31, 2013 using the fair value hierarchy:

At December 31, 2013

Total

Level I

Level II

Level III

Short-Term Investments

$

508,872,583

$

508,872,583

$

—

$

—

Exchange-Traded Futures

Contracts

Foreign Contracts

—

—

—

—

United States Contracts

2,724,970

2,724,970

—

—

During the year ended December 31, 2013, there were no transfers between Level I and Level II.

The following table summarizes the valuation of USO’s securities at December 31, 2012 using the fair value hierarchy:

At December 31, 2012

Total

Level I

Level II

Level III

Short-Term Investments

$

965,890,925

$

965,890,925

$

—

$

—

Exchange-Traded Futures

Contracts

Foreign Contracts

9,680,000

9,680,000

—

—

United States Contracts

57,500,420

57,500,420

—

—

During the year ended December 31, 2012, there were no transfers between Level I and Level II.

Effective January 1, 2009, USO adopted the provisions of Accounting Standards Codification 815 —Derivatives and Hedging, which require presentation of qualitative disclosures about objectives and strategies for using derivatives, quantitative disclosures about fair value amounts and gains and losses on derivatives.

Fair Value of Derivative Instruments

Statements of

Fair Value

Fair Value

Derivatives not

Financial

At

At

Accounted for as

Condition

December 31,

December 31,

Hedging Instruments

Location

2013

2012

Futures -

Commodity Contracts

Assets

$

2,724,970

$

67,180,420

The Effect of Derivative Instruments on the Statements of Operations

For the year ended

For the year ended

For the year ended

December 31, 2013

December 31, 2012

December 31, 2011

Change in

Change in

Change in

Derivatives

Location of

Realized

Unrealized

Realized

Unrealized

Realized

Unrealized

not Accounted

Gain or (Loss)

Gain or (Loss)

Gain or (Loss)

Gain or (Loss)

Gain or (Loss)

Gain or (Loss)

Gain or (Loss)

for as

on Derivatives

on Derivatives

on Derivatives

on Derivatives

on Derivatives

on Derivatives

on Derivatives

Hedging

Recognized

Recognized

Recognized

Recognized

Recognized

Recognized

Recognized

Instruments

in Income

in Income

in Income

in Income

in Income

in Income

in Income

Futures -

Realized gain (loss) on closed positions

$

144,592,660

$

-196,807,460

$

201,717,550

Commodity

Contracts

Change in unrealized gain (loss) on open positions

$

-64,455,450

$

73,652,730

$

-50,432,650

Recent_Accounting_Pronouncemen

Recent Accounting Pronouncements	12 Months Ended
	Dec. 31, 2013
Recent Accounting Pronouncements	'
	NOTE 9 - RECENT ACCOUNTING PRONOUNCEMENTS
	In December 2011, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2011-11, “Balance Sheet (Topic 210): Disclosures about Offsetting Assets and Liabilities.” The amendments in ASU No. 2011-11 require an entity to disclose information about offsetting and related arrangements to enable users of its financial statements to understand the effect of those arrangements on its financial position. ASU No. 2011-11 is effective for annual reporting periods beginning on or after January 1, 2013, and interim periods within those annual periods.

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2013
Subsequent Events	'
	NOTE 10 - SUBSEQUENT EVENTS
	USO has performed an evaluation of subsequent events through the date the financial statements were issued. This evaluation did not result in any subsequent events that necessitated disclosures and/or adjustments.

Summary_Of_Significant_Account1

Summary Of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2013
Revenue Recognition	'
	Revenue Recognition
	Commodity futures contracts, forward contracts, physical commodities, and related options are recorded on the trade date. All such transactions are recorded on the identified cost basis and marked to market daily. Unrealized gains or losses on open contracts are reflected in the statements of financial condition and represent the difference between the original contract amount and the market value (as determined by exchange settlement prices for futures contracts and related options and cash dealer prices at a predetermined time for forward contracts, physical commodities, and their related options) as of the last business day of the year or as of the last date of the financial statements. Changes in the unrealized gains or losses between periods are reflected in the statements of operations. USO earns interest on its assets denominated in U.S. dollars on deposit with the futures commission merchant at the overnight Federal Funds Rate less 32 basis points. In addition, USO earns income on funds held at the custodian or futures commission merchant at prevailing market rates earned on such investments.
Brokerage Commissions	'
	Brokerage Commissions
	Brokerage commissions on all open commodity futures contracts are accrued on a full-turn basis.
Income Taxes	'
	Income Taxes
	USO is not subject to federal income taxes; each partner reports his/her allocable share of income, gain, loss deductions or credits on his/her own income tax return.
	In accordance with accounting principles generally accepted in the United States of America (“GAAP”), USO is required to determine whether a tax position is more likely than not to be sustained upon examination by the applicable taxing authority, including resolution of any tax related appeals or litigation processes, based on the technical merits of the position. USO files an income tax return in the U.S. federal jurisdiction, and may file income tax returns in various U.S. states. USO is not subject to income tax return examinations by major taxing authorities for years before 2010. The tax benefit recognized is measured as the largest amount of benefit that has a greater than fifty percent likelihood of being realized upon ultimate settlement. De-recognition of a tax benefit previously recognized results in USO recording a tax liability that reduces net assets. However, USO’s conclusions regarding this policy may be subject to review and adjustment at a later date based on factors including, but not limited to, on-going analysis of and changes to tax laws, regulations and interpretations thereof. USO recognizes interest accrued related to unrecognized tax benefits and penalties related to unrecognized tax benefits in income tax fees payable, if assessed. No interest expense or penalties have been recognized as of and for the year ended December 31, 2013.
Creations and Redemptions	'
	Creations and Redemptions
	Authorized Purchasers may purchase Creation Baskets or redeem Redemption Baskets only in blocks of 100,000 shares at a price equal to the NAV of the shares calculated shortly after the close of the core trading session on the NYSE Arca on the day the order is placed.
	USO receives or pays the proceeds from shares sold or redeemed within three business days after the trade date of the purchase or redemption. The amounts due from Authorized Purchasers are reflected in USO’s statements of financial condition as receivable for shares sold, and amounts payable to Authorized Purchasers upon redemption are reflected as payable for shares redeemed.
Partnership Capital and Allocation of Partnership Income and Losses	'
	Partnership Capital and Allocation of Partnership Income and Losses
	Profit or loss shall be allocated among the partners of USO in proportion to the number of shares each partner holds as of the close of each month. USCF may revise, alter or otherwise modify this method of allocation as described in the LP Agreement.
Calculation of Per Share Net Asset Value	'
	Calculation of Per Share Net Asset Value
	USO’s per share NAV is calculated on each NYSE Arca trading day by taking the current market value of its total assets, subtracting any liabilities and dividing that amount by the total number of shares outstanding. USO uses the closing price for the contracts on the relevant exchange on that day to determine the value of contracts held on such exchange.
Net Income (Loss) Per Share	'
	Net Income (Loss) Per Share
	Net income (loss) per share is the difference between the per share NAV at the beginning of each period and at the end of each period. The weighted average number of shares outstanding was computed for purposes of disclosing net income (loss) per weighted average share. The weighted average shares are equal to the number of shares outstanding at the end of the period, adjusted proportionately for shares added and redeemed based on the amount of time the shares were outstanding during such period. There were no shares held by USCF at December 31, 2013.
Offering Costs	'
	Offering Costs
	Offering costs incurred in connection with the registration of additional shares after the initial registration of shares are borne by USO. These costs include registration fees paid to regulatory agencies and all legal, accounting, printing and other expenses associated with such offerings. These costs are accounted for as a deferred charge and thereafter amortized to expense over twelve months on a straight-line basis or a shorter period if warranted.
Cash Equivalents	'
	Cash Equivalents
	Cash equivalents include money market funds and overnight deposits or time deposits with original maturity dates of six months or less.
Reclassification	'
	Reclassification
	Certain amounts in the accompanying financial statements were reclassified to conform to the current presentation.
Use of Estimates	'
	Use of Estimates
	The preparation of financial statements in conformity with GAAP requires USCF to make estimates and assumptions that affect the reported amount of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of the revenue and expenses during the reporting period. Actual results may differ from those estimates and assumptions.

Financial_Highlights_Tables

Financial Highlights (Tables)	12 Months Ended
	Dec. 31, 2013
Per Unit Performance Data And Other Supplemental Financial Data	'
	The following table presents per share performance data and other supplemental financial data for the years ended December 31, 2013, 2012 and 2011. This information has been derived from information presented in the financial statements.
		Year ended			Year ended			Year ended
		December 31,			December 31,			December 31,
		2013			2012			2011
	Per Share Operating Performance:
	Net asset value, beginning of year	$	33.42		$	38.07		$	38.97
	Total income (loss)		2.08			-4.4			-0.65
	Total expenses		-0.27			-0.25			-0.25
	Net increase (decrease) in net		1.81			-4.65			-0.9
	asset value
	Net asset value, end of year	$	35.23		$	33.42		$	38.07
	Total Return		5.42	%		-12.21	%		-2.31	%
	Ratios to Average Net Assets
	Total income (loss)		9.12	%		-9.59	%		10.1	%
	Expenses excluding management		0.31	%		0.25	%		0.2	%
	fees
	Management fees		0.45	%		0.45	%		0.45	%
	Net income (loss)		8.36	%		-10.29	%		9.45	%

Quarterly_Financial_Data_Unaud1

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2013
Summarized (unaudited) quarterly financial information	'
	The following summarized (unaudited) quarterly financial information presents the results of operations and other data for three-month periods ended March 31, June 30, September 30 and December 31, 2013 and 2012.
		First		Second		Third		Fourth
		Quarter		Quarter		Quarter		Quarter
		2013		2013		2013		2013
	Total Income (Loss)	$	47,034,622	$	-5,519,969	$	66,272,544	$	-27,092,576
	Total Expenses		1,949,051		1,788,322		1,572,691		1,417,001
	Net Income (Loss)	$	45,085,571	$	-7,308,291	$	64,699,853	$	-28,509,577
	Net Income (Loss) per Share	$	1.37	$	-0.59	$	2.66	$	-1.63
		First		Second		Third		Fourth
		Quarter		Quarter		Quarter		Quarter
		2012		2012		2012		2012
	Total Income (Loss)	$	40,983,839	$	-227,301,113	$	808,817,737	$	-17,067,819
	Total Expenses		2,243,468		2,172,632		2,223,828		2,315,108
	Net Income (Loss)	$	38,740,371	$	-229,473,745	$	78,593,909	$	-19,382,927
	Net Income (Loss) per Share	$	1.14	$	-7.32	$	2.29	$	-0.76

Fair_Value_Of_Financial_Instru1

Fair Value Of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2013

Valuation of Securities Using Fair Value Hierarchy

'

The following table summarizes the valuation of USO’s securities at December 31, 2013 using the fair value hierarchy:

At December 31, 2013

Total

Level I

Level II

Level III

Short-Term Investments

$

508,872,583

$

508,872,583

$

—

$

—

Exchange-Traded Futures

Contracts

Foreign Contracts

—

—

—

—

United States Contracts

2,724,970

2,724,970

—

—

During the year ended December 31, 2013, there were no transfers between Level I and Level II.

The following table summarizes the valuation of USO’s securities at December 31, 2012 using the fair value hierarchy:

At December 31, 2012

Total

Level I

Level II

Level III

Short-Term Investments

$

965,890,925

$

965,890,925

$

—

$

—

Exchange-Traded Futures

Contracts

Foreign Contracts

9,680,000

9,680,000

—

—

United States Contracts

57,500,420

57,500,420

—

—

Fair Value of Derivative Instruments

'

Fair Value of Derivative Instruments

Statements of

Fair Value

Fair Value

Derivatives not

Financial

At

At

Accounted for as

Condition

December 31,

December 31,

Hedging Instruments

Location

2013

2012

Futures -

Commodity Contracts

Assets

$

2,724,970

$

67,180,420

Effect of Derivative Instruments on Condensed Statements of Operations

'

The Effect of Derivative Instruments on the Statements of Operations

For the year ended

For the year ended

For the year ended

December 31, 2013

December 31, 2012

December 31, 2011

Change in

Change in

Change in

Derivatives

Location of

Realized

Unrealized

Realized

Unrealized

Realized

Unrealized

not Accounted

Gain or (Loss)

Gain or (Loss)

Gain or (Loss)

Gain or (Loss)

Gain or (Loss)

Gain or (Loss)

Gain or (Loss)

for as

on Derivatives

on Derivatives

on Derivatives

on Derivatives

on Derivatives

on Derivatives

on Derivatives

Hedging

Recognized

Recognized

Recognized

Recognized

Recognized

Recognized

Recognized

Instruments

in Income

in Income

in Income

in Income

in Income

in Income

in Income

Futures -

Realized gain (loss) on closed positions

$

144,592,660

$

-196,807,460

$

201,717,550

Commodity

Contracts

Change in unrealized gain (loss) on open positions

$

-64,455,450

$

73,652,730

$

-50,432,650

Organization_and_Business_Addi

Organization and Business (Additional Information) (Detail) (USD $)	1 Months Ended
	Apr. 10, 2006	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
	Contract	Contract
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]	'	'		'	'	'
Fee paid by Authorized Purchasers for each order placed to create one or more Creation Baskets or to redeem one or more baskets	'	1,000		'	'	'
Number of initially registered units on Form S-1 with the U.S. Securities and Exchange Commission	17,000,000	'		'	'	'
Net asset value per unit	$67.39	$35.23		$33.42	$38.07	$38.97
Number of units issued	200,000	'		'	'	'
Value of units issued	$13,479,000	'		'	'	'
Number of registered units	'	1,627,000,000		'	'	'
Creation Baskets [Member]	'	'		'	'	'
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]	'	'		'	'	'
Number of units per basket	'	100,000		'	'	'
Open Futures Contracts, Long [Member]	'	'		'	'	'
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]	'	'		'	'	'
Number of Contracts	'	'		12,886	'	'
Open Futures Contracts, Long [Member] | United States [Member] | NYMEX Crude Oil Futures CL February contracts, expiring January [Member]	'	'		'	'	'
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]	'	'		'	'	'
Number of Contracts	'	5,835	[1]	10,886	'	'
Open Futures Contracts, Long [Member] | Foreign [Member] | ICE WTI Crude Oil Futures February contracts, expiring January [Member]	'	'		'	'	'
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items]	'	'		'	'	'
Number of Contracts	'	'		2,000	'	'
[1]	Collateral amounted to $20,806,873 on open futures contracts.

Recovered_Sheet1

Summary of Significant Accounting Policies (Additional Information) (Detail)	12 Months Ended
	Dec. 31, 2013
Significant Accounting Policies [Line Items]	'
Basis points subtracted from overnight Federal Funds Rate	32.00%
Minimum likelihood of tax benefits being recognized upon ultimate settlement	50.00%
Maximum [Member]	'
Significant Accounting Policies [Line Items]	'
Cash equivalents maturity period	'6 months
Redemption Baskets [Member]	'
Significant Accounting Policies [Line Items]	'
Number of units per basket	100,000

Fees_Paid_by_Fund_and_Related_

Fees Paid by Fund and Related Party Transactions (Additional Information) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fees Paid and Related Party Transactions [Line Items]	'	'	'
USCF Management Fee	'USO is contractually obligated to pay USCF a fee, which is paid monthly, equal to 0.45% per annum of average daily total net assets.	'	'
Percentage of average daily net assets	0.45%	'	'
Ongoing Registration Fees and Other Offering Expenses	$362,265	$176,971	$47,450
Licensing fee incurred	132,730	191,732	353,950
Estimated investor tax reporting cost	1,000,000	1,000,000	1,200,000
United States Oil Fund LP [Member]	'	'	'
Fees Paid and Related Party Transactions [Line Items]	'	'	'
Fees and expenses	195,352	235,481	229,954
USO And Related Public Funds [Member]	'	'	'
Fees Paid and Related Party Transactions [Line Items]	'	'	'
Fees and expenses	555,465	540,586	607,582
Licensing Agreements [Member] | First $1,000,000,000 of combined net assets of the funds [Member]	'	'	'
Fees Paid and Related Party Transactions [Line Items]	'	'	'
Fee percentage	0.04%	'	'
Licensing Agreements [Member] | First $1,000,000,000 of combined net assets of the funds [Member] | Maximum [Member]	'	'	'
Fees Paid and Related Party Transactions [Line Items]	'	'	'
Combined assets basis for determining fee percentage	1,000,000,000	'	'
Licensing Agreements [Member] | Combined net assets above $1,000,000,000 [Member]	'	'	'
Fees Paid and Related Party Transactions [Line Items]	'	'	'
Fee percentage	0.02%	'	'
Licensing Agreements [Member] | Combined net assets above $1,000,000,000 [Member] | Minimum [Member]	'	'	'
Fees Paid and Related Party Transactions [Line Items]	'	'	'
Combined assets basis for determining fee percentage	$1,000,000,000	'	'
Licensing Agreements [Member] | On and after October 20, 2011 [Member]	'	'	'
Fees Paid and Related Party Transactions [Line Items]	'	'	'
Fee percentage	0.02%	'	'
Assets basis for determining fee percentage	'all net assets	'	'

Contracts_and_Agreements_Addit

Contracts and Agreements (Additional Information) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Annual fee for transfer agency services	$20,000	'	'
Brokerage commissions	965,576	1,298,827	1,529,433
Ratio of expense to Average Net Assets	0.11%	0.10%	0.10%
Minimum [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Annual fee for custody, fund accounting and fund administration services	75,000	'	'
Transaction fees per transaction	7	'	'
Commissions per round-turn trade, including applicable exchange and NFA fees for Oil Futures Contracts and options on Oil Futures Contracts	7	'	'
Maximum [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Transaction fees per transaction	15	'	'
Commissions per round-turn trade, including applicable exchange and NFA fees for Oil Futures Contracts and options on Oil Futures Contracts	15	'	'
Rebalancing Investments Transaction [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Brokerage commissions	697,519	1,061,305	1,148,618
Floor Brokerage Exchange And Clearance Fees Percentage	72.34%	81.71%	75.10%
Trades Necessitated By Creation And Redemption Activity [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Brokerage commissions	267,057	237,522	380,815
Floor Brokerage Exchange And Clearance Fees Percentage	27.66%	18.29%	24.90%
First $500 million of USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Fee percentage	0.06%	'	'
First $500 million of USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets [Member] | Maximum [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Base amount for determining fee percentage	500,000,000	'	'
USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets greater than $500 million but less than $1 billion [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Fee percentage	0.05%	'	'
USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets greater than $500 million but less than $1 billion [Member] | Minimum [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Base amount for determining fee percentage	500,000,000	'	'
USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets greater than $500 million but less than $1 billion [Member] | Maximum [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Base amount for determining fee percentage	1,000,000,000	'	'
USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets exceed $1 billion [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Fee percentage	0.04%	'	'
USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets exceed $1 billion [Member] | Minimum [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Base amount for determining fee percentage	1,000,000,000	'	'
USOF's assets from $500 million - $4 billion [Member] | Minimum [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Base amount for determining fee percentage	500,000,000	'	'
Marketing Agreement [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Marketing fee exclusive of the incentive fee	425,000	'	'
Marketing Agreement [Member] | USOF's assets from $0- $500 million [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Fee percentage	0.00%	'	'
Marketing Agreement [Member] | USOF's assets from $0- $500 million [Member] | Minimum [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Base amount for determining fee percentage	0	'	'
Marketing Agreement [Member] | USOF's assets from $0- $500 million [Member] | Maximum [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Base amount for determining fee percentage	500,000,000	'	'
Marketing Agreement [Member] | USOF's assets from $500 million - $4 billion [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Fee percentage	0.04%	'	'
Marketing Agreement [Member] | USOF's assets from $500 million - $4 billion [Member] | Maximum [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Base amount for determining fee percentage	4,000,000,000	'	'
Marketing Agreement [Member] | USOF's assets in excess of $4 billion [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Fee percentage	0.03%	'	'
Marketing Agreement [Member] | USOF's assets in excess of $4 billion [Member] | Minimum [Member]	'	'	'
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]	'	'	'
Base amount for determining fee percentage	$4,000,000,000	'	'

Financial_Instruments_OffBalan1

Financial Instruments, Off-Balance Sheet Risks and Contingencies (Additional Information) (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Money Market Funds [Member]	'	'
Loss Contingencies [Line Items]	'	'
Deposits in domestic and foreign financial institutions, including cash investments in money market funds	$308,914,222	$745,914,221
US Treasury Securities [Member]	'	'
Loss Contingencies [Line Items]	'	'
Deposits in domestic and foreign financial institutions, including cash investments in money market funds	$282,768,437	$427,853,549

Financial_Highlights_Per_Unit_

Financial Highlights (Per Unit Performance Data and Other Supplemental Financial Data) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Apr. 10, 2006
Per Unit Operating Performance:	'	'	'	'
Net asset value, beginning of year	$33.42	$38.07	$38.97	$67.39
Total income (loss)	$2.08	($4.40)	($0.65)	'
Total expenses	($0.27)	($0.25)	($0.25)	'
Net increase (decrease) in net asset value	$1.81	($4.65)	($0.90)	'
Net asset value, end of year	$35.23	$33.42	$38.07	$67.39
Total Return	5.42%	-12.21%	-2.31%	'
Ratios to Average Net Assets	'	'	'	'
Total income (loss)	9.12%	-9.59%	10.10%	'
Expenses excluding management fees	0.31%	0.25%	0.20%	'
Management fees	0.45%	0.45%	0.45%	'
Net income (loss)	8.36%	-10.29%	9.45%	'

Quarterly_Financial_Data_Unaud2

Quarterly Financial Data (Unaudited) (Summarized (Unaudited) Quarterly Financial Information) (Detail) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly Financial Information [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Total Income (Loss)	($27,092,576)	$66,272,544	($5,519,969)	$47,034,622	($17,067,819)	$808,817,737	($227,301,113)	$40,983,839	$80,694,621	($122,567,356)	$151,829,866
Total Expenses	1,417,001	1,572,691	1,788,322	1,949,051	2,315,108	2,223,828	2,172,632	2,243,468	6,727,065	8,955,036	9,804,068
Net income (loss)	($28,509,577)	$64,699,853	($7,308,291)	$45,085,571	($19,382,927)	$78,593,909	($229,473,745)	$38,740,371	$73,967,556	($131,522,392)	$142,025,798
Net Income (Loss) per Share	($1.63)	$2.66	($0.59)	$1.37	($0.76)	$2.29	($7.32)	$1.14	$1.81	($4.65)	($0.90)

Fair_Value_Of_Financial_Instru2

Fair Value Of Financial Instruments (Valuation of Securities Using Fair Value Hierarchy) (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Short-Term Investments [Member]	'	'
Schedule of Trading Securities and Other Trading Assets [Line Items]	'	'
Securities, fair value	$508,872,583	$965,890,925
Exchange-Traded Futures Contracts [Member] | Foreign [Member]	'	'
Schedule of Trading Securities and Other Trading Assets [Line Items]	'	'
Securities, fair value	0	9,680,000
Exchange-Traded Futures Contracts [Member] | United States [Member]	'	'
Schedule of Trading Securities and Other Trading Assets [Line Items]	'	'
Securities, fair value	2,724,970	57,500,420
Fair Value, Inputs, Level 1 [Member] | Short-Term Investments [Member]	'	'
Schedule of Trading Securities and Other Trading Assets [Line Items]	'	'
Securities, fair value	508,872,583	965,890,925
Fair Value, Inputs, Level 1 [Member] | Exchange-Traded Futures Contracts [Member] | Foreign [Member]	'	'
Schedule of Trading Securities and Other Trading Assets [Line Items]	'	'
Securities, fair value	0	9,680,000
Fair Value, Inputs, Level 1 [Member] | Exchange-Traded Futures Contracts [Member] | United States [Member]	'	'
Schedule of Trading Securities and Other Trading Assets [Line Items]	'	'
Securities, fair value	$2,724,970	$57,500,420

Fair_Value_Of_Financial_Instru3

Fair Value Of Financial Instruments (Fair Value of Derivative Instruments) (Detail) (Futures [Member], Commodity Contracts [Member], Assets [Member], USD $)	Dec. 31, 2013	Dec. 31, 2012
Futures [Member] | Commodity Contracts [Member] | Assets [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivatives not Accounted for as Hedging Instruments	$2,724,970	$67,180,420

Fair_Value_Of_Financial_Instru4

Fair Value Of Financial Instruments (Effect of Derivative Instruments on Statements of Operations) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'
Realized Gain or (Loss) on Derivatives Recognized in Income	$144,592,660	($196,807,460)	$201,717,550
Change in Unrealized Gain or (Loss) on Derivatives Recognized in Income	-64,455,450	73,652,730	-50,432,650
Commodity Contracts [Member] | Realized gain (loss) on closed positions [Member]	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'
Realized Gain or (Loss) on Derivatives Recognized in Income	144,592,660	-196,807,460	201,717,550
Commodity Contracts [Member] | Change in unrealized gain (loss) on open positions [Member]	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'
Change in Unrealized Gain or (Loss) on Derivatives Recognized in Income	($64,455,450)	$73,652,730	($50,432,650)