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Condensed Schedule of Investments (Parenthetical) (USD $)	3 Months Ended
	Mar. 31, 2015
Collateral Amount On Open Futures Contracts	369,394,262uso_CollateralAmountOnOpenFuturesContracts
United States [Member] | US Treasury Bill Securities One [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.05%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesOneMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	4/23/2015
United States [Member] | US Treasury Bill Securities Two [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.07%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesTwoMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	5/21/2015
United States [Member] | US Treasury Bill Securities Three [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.02%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesThreeMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	5/28/2015
United States [Member] | US Treasury Bill Securities Four [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.05%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesFourMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	6/4/2015
United States [Member] | US Treasury Bill Securities Five [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.03%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesFiveMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	6/11/2015
United States [Member] | US Treasury Bill Securities Six [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.03%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesSixMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	6/18/2015
United States [Member] | US Treasury Bill Securities Seven [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.10%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesSevenMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	6/25/2015
United States [Member] | US Treasury Bill Securities Eight [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.03%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesEightMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	7/2/2015
United States [Member] | Us Treasury Bill Securities Nine [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.06%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesNineMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	7/9/2015
United States [Member] | Us Treasury Bill Securities Ten [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.05%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesTenMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	7/16/2015
United States [Member] | Us Treasury Bill Securities Eleven [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.08%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesElevenMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	7/23/2015
United States [Member] | Us Treasury Bill Securities Twelve [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.06%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesTwelveMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	7/30/2015
United States [Member] | Us Treasury Bill Securities Thirteen [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.06%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesThirteenMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	8/6/2015
United States [Member] | Us Treasury Bill Securities Fourteen [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.07%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesFourteenMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	8/13/2015
United States [Member] | Us Treasury Bill Securities Fifteen [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.07%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesFifteenMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	8/20/2015
United States [Member] | Us Treasury Bill Securities Sixteen [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.07%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesSixteenMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	8/27/2015
United States [Member] | Us Treasury Bill Securities Seventeen [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.08%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesSeventeenMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	9/3/2015
United States [Member] | Us Treasury Bill Securities Eighteen [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.10%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesEighteenMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	9/10/2015
United States [Member] | Us Treasury Bill Securities Nineteen [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.12%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesNineteenMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	9/17/2015
United States [Member] | Us Treasury Bill Securities Twenty [Member] | US Treasury Securities [Member] | Cash Equivalent [Member]
Interest rate	0.11%us-gaap_DebtInstrumentInterestRateStatedPercentage / invest_InvestmentGeographicRegionAxis = country_US / invest_InvestmentSecuritiesClassAxis = us-gaap_USTreasurySecuritiesMember / invest_InvestmentSecuritiesSeriesAxis = uso_UsTreasuryBillSecuritiesTwentyMember / us-gaap_InvestmentTypeAxis = us-gaap_CashEquivalentsMember
Expiration date	9/24/2015

X

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

The list of dates or date range within which the options may be exercised of the investment subject to option.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 946

-SubTopic 320

-Section S99

-Paragraph 6

-Subparagraph (SX 210.12-14.4(b))

-URI http://asc.fasb.org/extlink&oid=34726532&loc=d3e611322-123010



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 14

-Paragraph 4

-Subparagraph b

-Article 12



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 946

-SubTopic 320

-Section S99

-Paragraph 5

-Subparagraph (SX 210.12-13.5(d))

-URI http://asc.fasb.org/extlink&oid=34726532&loc=d3e611282-123010



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 13

-Paragraph 5

-Subparagraph d

-Article 12

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- Definition

Collateral Amount On Open Futures Contracts.

+ References

No definition available.

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