XML 40 R81.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Commitments And Contingencies [Line Items] |  |  |
Rental expense | $ 2.0 us-gaap_OperatingLeasesRentExpenseNet | $ 1.6 us-gaap_OperatingLeasesRentExpenseNet | $ 1.5 us-gaap_OperatingLeasesRentExpenseNet
Future Obligations Under Cost Sharing Agreements | 9.0 oas_FutureObligationsUnderCostSharingAgreements |  |
Capital spending commitment | 4.8 oas_CapitalSpendingCommitment |  |
Long Term Commitments [Member] |  |  |
Commitments And Contingencies [Line Items] |  |  |
Supply Commitment, Maximum Term | 10 years |  |
Future obligations under supply agreements | 194.0 oas_FutureObligationsUnderSupplyAgreements / us-gaap_SupplyCommitmentAxis = oas_LongTermCommitmentsMember |  |
Long Term Commitments [Member] | Williston Basin Project [Member] | Crude oil collar [Member] |  |  |
Commitments And Contingencies [Line Items] |  |  |
Minimum quantity of delivery | 31,700 us-gaap_OilAndGasDeliveryCommitmentsAndContractsRemainingContractualVolume / us-gaap_EnergyAxis = us-gaap_CrudeOilMember / us-gaap_ProductOrServiceAxis = oas_WillistonBasinProjectMember / us-gaap_SupplyCommitmentAxis = oas_LongTermCommitmentsMember |  |
Long Term Commitments [Member] | Williston Basin Project [Member] | Natural Gas [Member] |  |  |
Commitments And Contingencies [Line Items] |  |  |
Minimum quantity of delivery | 7,900 us-gaap_OilAndGasDeliveryCommitmentsAndContractsRemainingContractualVolume / us-gaap_EnergyAxis = us-gaap_NaturalGasReservesMember / us-gaap_ProductOrServiceAxis = oas_WillistonBasinProjectMember / us-gaap_SupplyCommitmentAxis = oas_LongTermCommitmentsMember |  |
Drilling contracts [Member] |  |  |
Commitments And Contingencies [Line Items] |  |  |
Payments upon early contract termination | 15.0 us-gaap_LossOnContractTermination / us-gaap_LossContingenciesByNatureOfContingencyAxis = oas_DrillingContractsMember |  |
Well Completion Services Equipment and Fresh Water [Member] |  |  |
Commitments And Contingencies [Line Items] |  |  |
Long-term Purchase Commitment, Amount | $ 20.0 us-gaap_LongTermPurchaseCommitmentAmount / us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis = oas_WellCompletionServicesEquipmentandFreshWaterMember |  |

X
- Definition Capital Spending Commitment + References No definition available. + Details
Name: | oas_CapitalSpendingCommitment
Namespace Prefix: | oas_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | oas_CommitmentsAndContingenciesLineItems
Namespace Prefix: | oas_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Future Obligations Under Cost Sharing Agreements + References No definition available. + Details
Name: | oas_FutureObligationsUnderCostSharingAgreements
Namespace Prefix: | oas_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Future obligations under supply agreements + References No definition available. + Details
Name: | oas_FutureObligationsUnderSupplyAgreements
Namespace Prefix: | oas_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Supply Commitment, Maximum Term + References No definition available. + Details
Name: | oas_SupplyCommitmentMaximumTerm
Namespace Prefix: | oas_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The minimum amount the entity agreed to spend under the long-term purchase commitment. + References No definition available. + Details
Name: | us-gaap_LongTermPurchaseCommitmentAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The loss recognized on termination of a contract. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 912 -SubTopic 275 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6471736&loc=d3e54681-109401 + Details
Name: | us-gaap_LossOnContractTermination
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Total amount of product committed to be supplied under existing contracts or agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Industry Guide -Number 2 -Paragraph 8 -Subparagraph A + Details
Name: | us-gaap_OilAndGasDeliveryCommitmentsAndContractsRemainingContractualVolume
Namespace Prefix: | us-gaap_
Data Type: | num:volumeItemType
Balance Type: | na
Period Type: | instant

X
- Definition Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41499-112717 + Details
Name: | us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_LongTermPurchaseCommitmentByCategoryOfItemPurchasedAxis=oas_WellCompletionServicesEquipmentandFreshWaterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LossContingenciesByNatureOfContingencyAxis=oas_DrillingContractsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SupplyCommitmentAxis=oas_LongTermCommitmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |