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Derivative Instruments - Schedule of Outstanding Commodity Derivative Instruments (Detail) (USD $) In Thousands, unless otherwise specified | Mar. 31, 2015
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Derivative [Line Items] |
Fair Value Asset (Liability) | $ 253,320 us-gaap_DerivativeFairValueOfDerivativeNet
2015 Two-Way Collars [Member] |
Derivative [Line Items] |
Total Notional Amount of Oil (Barrels) | 1,402 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenTwoWayCollarsMember
Average Floor Price (in dollars per barrel) | 86.52 us-gaap_DerivativeAverageFloorPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenTwoWayCollarsMember
Average Ceiling Price (in dollars per barrel) | 102.86 us-gaap_DerivativeAverageCapPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenTwoWayCollarsMember
Fair Value Asset (Liability) | 57,100 us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenTwoWayCollarsMember
2015 Swaps [Member] |
Derivative [Line Items] |
Total Notional Amount of Oil (Barrels) | 3,381 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenSwapContractsMember
Average Swap Price (in dollars per barrel) | 89.36 us-gaap_DerivativeSwapTypeAverageFixedPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenSwapContractsMember
Fair Value Asset (Liability) | 152,359 us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenSwapContractsMember
2015 Deferred Premium Puts [Member] |
Derivative [Line Items] |
Total Notional Amount of Oil (Barrels) | 546 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenDeferredPremiumPutsMember
Average Floor Price (in dollars per barrel) | 90.00 us-gaap_DerivativeAverageFloorPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenDeferredPremiumPutsMember
Average deferred premium (in dollars per barrel) | 2.55 oas_DerivativeAverageDeferredPremium / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenDeferredPremiumPutsMember
Fair Value Asset (Liability) | 28,188 us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandFifteenDeferredPremiumPutsMember
2016 Two Way Collars [Member] |
Derivative [Line Items] |
Total Notional Amount of Oil (Barrels) | 155 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandSixteenTwoWayCollarsMember
Average Floor Price (in dollars per barrel) | 86.00 us-gaap_DerivativeAverageFloorPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandSixteenTwoWayCollarsMember
Average Ceiling Price (in dollars per barrel) | 103.42 us-gaap_DerivativeAverageCapPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandSixteenTwoWayCollarsMember
Fair Value Asset (Liability) | 4,717 us-gaap_DerivativeFairValueOfDerivativeNet / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandSixteenTwoWayCollarsMember
2016 Swaps [Member] |
Derivative [Line Items] |
Total Notional Amount of Oil (Barrels) | 372 invest_DerivativeNonmonetaryNotionalAmount / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandSixteenSwapsMember
Average Swap Price (in dollars per barrel) | 85.27 us-gaap_DerivativeSwapTypeAverageFixedPrice / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = oas_TwoThousandSixteenSwapsMember
Fair Value Asset (Liability) | $ 10,956 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 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=49121117&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=49121117&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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