2.4.0.81050 - Disclosure - Divestituretruefalsefalse1false falsefalseD2013Q2YTDhttp://www.sec.gov/CIK0001166036duration2013-01-01T00:00:002013-06-30T00:00:001true 1mwe_DivestitureDisclosureAbstractmwe_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Divestiture2false 2us-gaap_DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlockus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00<div style="font-size:10.0pt;font-family:Times New Roman;"> 5. Divestiture   In June 2013, the Partnership completed the sale of certain gathering assets in Doddridge County, West Virginia (“Sherwood Asset Sale”) to Summit Midstream Partners, LP (“Summit”) for approximately $207.9 million cash, net of third party transaction costs.  In connection with the transaction, Summit assumed liabilities associated with the purchased assets other than certain identified liabilities that were retained by the Partnership.  Liquids-rich gas gathered by these assets is dedicated to the Partnership for processing at the Liberty segment’s Sherwood processing complex, also located in Doddridge County, West Virginia. The assets included in this transaction consist of over 40 miles of newly constructed high-pressure gas gathering pipelines, certain rights-of-way associated with the pipeline, and two compressor stations totaling over 21,000 horsepower of combined compression.  The assets had a carrying value of approximately $169.7 million and were part of the Partnership’s Liberty segment.  The gain of approximately $38.2 million on the Sherwood Asset Sale is included in Gain (loss) on disposal of property, plant, and equipment in the accompanying Condensed Consolidated Statements of Operations.   </div>falsefalsefalsenonnum:textBlockItemTypenaThe entire disclosure for the facts and circumstances leading to the completed or expected disposal, manner and timing of disposal, the gain (loss) recognized in the income statement and the income statement caption that includes that gain (loss), amounts of revenues and pretax profit or loss reported in discontinued operations, the segment in which the disposal group was reported, and the classification (whether sold or classified as held for sale) and carrying value of the assets and liabilities comprising the disposal group. Includes all disposal groups, including those classified as components of the entity (discontinued operations).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 43-48 -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. 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