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Significant Concentration - Additional Information (Detail) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2012 | Dec. 31, 2011 Oil And Natural Gas [Member] | Dec. 31, 2010 JIB Receivables [Member] | Dec. 31, 2011 Northern Oil & Gas Inc [Member] | Dec. 31, 2011 Hess Corporation [Member]
Significant Concentrations [Line Items] |  |  |  |  |
Purchasers accounted for more than 10% of the Company's total sales | No other | No other | No other |  |
Percentage oil and gas joint interest billing receivables |  |  |  | 16.00% | 14.00%

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- Definition Percentage of joint interest billing receivables generated from a single external customer that accounts for 10 percent or more of an entity's joint interest billing receivables. + References No definition available. + Details
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Namespace Prefix: | oas_
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- Details
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- Definition Disclosure of the extent of enterprise reliance on its major customers. For example, includes revenues from transactions with a single external customer amounting to 10 percent or more of the entity's revenues, the total amount of revenues from each such customer, and the identity of the segment or segments reporting the revenues. A group of entities that the entity knows to be under common control generally will be considered a single customer for inclusion in this item. The federal government, a state government, a local government (for example, a county or municipality), or a foreign government each will generally be considered as a single customer for inclusion in this item. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 131 -Paragraph 39 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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