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Derivative Instruments - Schedule of Outstanding Commodity Derivative Instruments (Detail) (USD $) In Thousands, unless otherwise specified | Dec. 31, 2014
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Derivative [Line Items] |
Fair value asset (liability) | $ 315,507 us-gaap_DerivativeFairValueOfDerivativeNet
2015 Two-way collar [Member] |
Derivative [Line Items] |
Total notional amount of oil barrels | 2,388.5 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenTwoWayCollarMember
Average floor price | 87.98 us-gaap_DerivativeAverageFloorPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenTwoWayCollarMember
Average ceiling price | 103.21 us-gaap_DerivativeAverageCapPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenTwoWayCollarMember
Fair value asset (liability) | 75,271 us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenTwoWayCollarMember
2015 Three-way collars [Member] |
Derivative [Line Items] |
Total notional amount of oil barrels | 263.5 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenThreeWayCollarsMember
Average sub-floor price | 70.59 oas_DerivativeAverageSubFloorPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenThreeWayCollarsMember
Average floor price | 90.59 us-gaap_DerivativeAverageFloorPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenThreeWayCollarsMember
Average ceiling price | 105.25 us-gaap_DerivativeAverageCapPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenThreeWayCollarsMember
Fair value asset (liability) | 5,270 us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenThreeWayCollarsMember
2015 Swaps [Member] |
Derivative [Line Items] |
Total notional amount of oil barrels | 5,263.5 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenSwapContractsMember
Average swap price | 90.81 us-gaap_DerivativeSwapTypeAverageFixedPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenSwapContractsMember
Fair value asset (liability) | 181,980 us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenSwapContractsMember
2015 Swaps with subfloors [Member] |
Derivative [Line Items] |
Total notional amount of oil barrels | 186.0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenSwapContractswithSubfloorsMember
Average swap price | 92.60 us-gaap_DerivativeSwapTypeAverageFixedPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenSwapContractswithSubfloorsMember
Average sub-floor price | 70.00 oas_DerivativeAverageSubFloorPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenSwapContractswithSubfloorsMember
Fair value asset (liability) | 4,204 us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenSwapContractswithSubfloorsMember
Two Thousand Fifteen Deferred Premium Puts [Member] |
Derivative [Line Items] |
Total notional amount of oil barrels | 1,086.0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenDeferredPremiumPutsMember
Average floor price | 90.00 us-gaap_DerivativeAverageFloorPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenDeferredPremiumPutsMember
Weighted average deferred premium | 2.55 oas_DerivativeAverageDeferredPremium / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenDeferredPremiumPutsMember
Fair value asset (liability) | 35,434 us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenDeferredPremiumPutsMember
Two Thousand Sixteen Two Way Collars [Member] |
Derivative [Line Items] |
Total notional amount of oil barrels | 155.0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandSixteenTwoWayCollarsMember
Average floor price | 86.00 us-gaap_DerivativeAverageFloorPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandSixteenTwoWayCollarsMember
Average ceiling price | 103.42 us-gaap_DerivativeAverageCapPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandSixteenTwoWayCollarsMember
Fair value asset (liability) | 4,138 us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandSixteenTwoWayCollarsMember
Two Thousand Sixteen Swaps [Member] |
Derivative [Line Items] |
Total notional amount of oil barrels | 310.0 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandSixteenSwapsMember
Average swap price | 90.15 us-gaap_DerivativeSwapTypeAverageFixedPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandSixteenSwapsMember
Fair value asset (liability) | $ 9,210 us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandSixteenSwapsMember

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- Definition Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition The average strike price of the sold put that establishes the price at which if the market price falls below, the minimum price would be index price plus the difference between the purchased put (floor) and the sold put strike price. + References No definition available. + Details
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- Definition The average cap rate on a group of price risk derivatives such as caps or collars. A payment or receipt is triggered if the market rate exceeds the cap rate on the contract. + References No definition available. + Details
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- Definition The average floor rate on a group of price risk derivatives such as floors or collars. A payment or receipt is triggered if the market rate falls below the floor rate on the contract. + References No definition available. + Details
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- Definition Fair value of the assets less the liabilities of a derivative or group of derivatives. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13495-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 + Details
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- Definition Average fixed price related to the group of price risk swap derivatives. + References No definition available. + Details
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