Aggregate notional amount of derivative expressed in nonmonetary units. For example, the number of barrels specified in a fuel oil forward purchase contract.

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

Name:	invest_DerivativeNonmonetaryNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Loans Receivable, Term

+ References

No definition available.

+ Details

Name:	oas_LoansReceivableTerm
Namespace Prefix:	oas_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: 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

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Average fixed price related to the group of price risk swap derivatives.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeSwapTypeAverageFixedPrice
Namespace Prefix:	us-gaap_
Data Type:	us-types:perUnitItemType
Balance Type:	na
Period Type:	instant

- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

Name:	us-gaap_ExtinguishmentOfDebtAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes loans held for sale. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(a))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_LoansReceivableNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cash inflow to dispose of long-lived, physical assets and mineral interests in oil and gas properties used for normal oil and gas operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3179-108585

+ Details

Name:	us-gaap_ProceedsFromSaleOfOilAndGasPropertyAndEquipment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Yield on the receivable, on which interest has been imputed, as calculated from its issuance value or purchase price. The calculated effective interest rate considers factors such as the issued face value or price paid for the receivable, the time period between payments, and the time until maturity [full receipt] of the receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

Name:	us-gaap_ReceivableWithImputedInterestEffectiveYieldInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow to repay long-term debt that is not secured by collateral. Excludes repayments of tax exempt unsecured debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3291-108585

+ Details

Name:	us-gaap_RepaymentsOfUnsecuredDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_UnsecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=oas_PurchasedNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=oas_TwoThousandNineteenNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=oas_TwoThousandTwentyOneNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=oas_TwoThousandTwentyTwoNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=oas_TwoThousandSixteenSwapsandThreewayCostlessCollarsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=oas_TwoThousandSeventeenSwapsandThreewayCostlessCollarsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=oas_TwoThousandEighteenSwapsandThreewayCostlessCollarsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Subsequent Events (Details) $ in Thousands		1 Months Ended		3 Months Ended
Subsequent Events (Details) $ in Thousands	Apr. 01, 2016 USD ($)	Apr. 30, 2016 USD ($) $ / bbl	Mar. 31, 2016 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	May. 10, 2016 MBbls
Subsequent Event [Line Items]
Repurchase of senior unsecured debt				$ 22,308	$ 0
Senior Unsecured Debt [Member] \| Purchased Notes [Member]
Subsequent Event [Line Items]
Amount of debt extinguished			$ 29,800
Repurchase of senior unsecured debt			$ 22,300
Senior Unsecured Debt [Member] \| 7.25% senior unsecured notes due February 1, 2019 [Member]
Subsequent Event [Line Items]
Stated interest rate (as percent)			7.25%	7.25%
Senior Unsecured Debt [Member] \| 6.5% senior unsecured notes due November 1, 2021 [Member]
Subsequent Event [Line Items]
Amount of debt extinguished			$ 1,000
Stated interest rate (as percent)			6.50%	6.50%
Senior Unsecured Debt [Member] \| 6.875% senior unsecured notes due March 15, 2022 [Member]
Subsequent Event [Line Items]
Amount of debt extinguished			$ 15,000
Stated interest rate (as percent)			6.875%	6.875%
Subsequent Event [Member]
Subsequent Event [Line Items]
Proceeds from sale of legacy wells	$ 12,200
Loans receivable	$ 4,000
Interest rate of receivable (as percent)	10.00%
Term of loan receivable	1 year
Average swap price (in dollars per barrel) \| $ / bbl		46.23
Subsequent Event [Member] \| 2016 Swaps and Three-way costless collars [Member]
Subsequent Event [Line Items]
Total notional amount of oil (in MBbls) \| MBbls						153
Subsequent Event [Member] \| 2017 Swaps and Three-way costless collars [Member]
Subsequent Event [Line Items]
Total notional amount of oil (in MBbls) \| MBbls						1,061
Subsequent Event [Member] \| 2018 Swaps and Three-way costless collars [Member]
Subsequent Event [Line Items]
Total notional amount of oil (in MBbls) \| MBbls						62
Subsequent Event [Member] \| Senior Unsecured Debt [Member] \| Purchased Notes [Member]
Subsequent Event [Line Items]
Amount of debt extinguished		$ 46,800
Repurchase of senior unsecured debt		34,600
Subsequent Event [Member] \| Senior Unsecured Debt [Member] \| 7.25% senior unsecured notes due February 1, 2019 [Member]
Subsequent Event [Line Items]
Amount of debt extinguished		$ 1,000
Stated interest rate (as percent)		7.25%
Subsequent Event [Member] \| Senior Unsecured Debt [Member] \| 6.5% senior unsecured notes due November 1, 2021 [Member]
Subsequent Event [Line Items]
Amount of debt extinguished		$ 1,300
Stated interest rate (as percent)		6.50%
Subsequent Event [Member] \| Senior Unsecured Debt [Member] \| 6.875% senior unsecured notes due March 15, 2022 [Member]
Subsequent Event [Line Items]
Amount of debt extinguished		$ 44,500
Stated interest rate (as percent)		6.875%