2.2.0.7 false Recent Accounting Pronouncements 1020 - Disclosure - Recent Accounting Pronouncements true false false false 1 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDPerShare Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 $ 2 Recent Accounting Pronouncements 0 mwe_RecentAccountingPronouncementsDisclosureAbstract mwe false na duration No definition available. false false false false false true false false false false false false 1 false false false false 0 0 false false false xbrli:stringItemType string No definition available. false 3 Recent Accounting Pronouncements 1 us-gaap_ScheduleOfNewAccountingPronouncementsAndChangesInAccountingPrinciplesTextBlock us-gaap true na duration No definition available. false false false false false false false false false false false terselabel false 1 false false false false 0 0 <table style="font-size:10pt; font-family:'Times New Roman',times,serif;"> <tr> <td> 2. Recent Accounting Pronouncements         In June 2009, the FASB amended the VIE subsections of the consolidation guidance. The amended guidance changes the criteria for determining if a VIE exists and whether or not a VIE should be consolidated. The amended guidance was effective for the Partnership on January 1, 2010, and the Partnership reconsidered its previous VIE conclusions and financial statement disclosures. The amendment had no effect on the Partnership's condensed consolidated financial statements.         In September 2009, the FASB amended the accounting guidance for revenue recognition for multiple-deliverable arrangements. The amended guidance establishes a hierarchy for determining the selling price of each individual deliverable and eliminates the residual value method of allocating the selling price. The amended guidance is effective prospectively for all revenue arrangements entered into or materially modified in fiscal years beginning after June 15, 2010. The amendment is not expected to have a material effect on the Partnership's condensed consolidated financial statements.         In February 2010, the FASB amended the embedded derivative and hedging guidance. The amended guidance modified the requirements for determining whether an embedded derivative is clearly and closely related to the host contract. The amended embedded derivative guidance was effective for the Partnership on January 1, 2010. The amended guidance had no effect on the Partnership's condensed consolidated financial statements.         In March 2010, the FASB amended a scope exception for embedded credit derivatives in the derivatives and hedging guidance. The amended guidance clarified which types of embedded credit derivative features are required to be analyzed for potential bifurcation. The amended guidance is effective for the Partnership on July 1, 2010. The amended guidance will have no effect on the Partnership's condensed consolidated financial statements. </td></tr></table> 2. Recent Accounting Pronouncements         In June 2009, the FASB amended the VIE subsections of the consolidation false false false us-types:textBlockItemType textblock Represents disclosure of any changes in an accounting principle, including a change from one generally accepted accounting principle to another generally accepted accounting principle when there are two or more generally accepted accounting principles that apply or when the accounting principle formerly used is no longer generally accepted. Also disclose any change in the method of applying an accounting principle, or any change in an accounting principle required by a new pronouncement in the unusual instance that a new pronouncement does not include specific transition provisions. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 154 -Paragraph 2, 17, 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 28 -Paragraph 23, 24 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 01 -Paragraph b -Subparagraph 6 -Article 10 false 1 2 false UnKnown UnKnown UnKnown false true