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May include the following: gathering from wells, processing to remove impurities, storage, transmission, and the sale of natural gas and related products. No authoritative reference available. false 7 Derivative (loss) gain 4 mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToRevenue mwe false credit duration Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of price risk... false false false false false false false false false false false terselabel false 1 false true false false -36959000 -36959 false false false 2 false true false false 9758000 9758 false false false 3 false true false false 2707000 2707 false false false 4 false true false false -65173000 -65173 false false false xbrli:monetaryItemType monetary Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of price risk derivatives not designated as hedging instruments. Revenue gains and losses relate to contracts utilized to economically hedge the cash flow for the sale of a product. No authoritative reference available. false 8 Total revenue 4 us-gaap_Revenues us-gaap true credit duration No definition available. false false false false false false false false false false false totallabel false 1 false true false false 255411000 255411 false false false 2 false true false false 217691000 217691 false false false 3 false true false false 887640000 887640 false false false 4 false true false false 511127000 511127 false false false xbrli:monetaryItemType monetary Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Article 5 true 9 Operating expenses: 3 us-gaap_CostsAndExpensesAbstract us-gaap true na duration No definition available. false false false false false true false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false xbrli:stringItemType string No definition available. false 10 Purchased product costs 4 us-gaap_NaturalGasMidstreamCosts us-gaap true debit duration No definition available. false false false false false false false false false false false terselabel false 1 false true false false 136700000 136700 false false false 2 false true false false 91086000 91086 false false false 3 false true false false 409119000 409119 false false false 4 false true false false 274052000 274052 false false false xbrli:monetaryItemType monetary Cost of residue gas, natural gas liquids and condensate. Midstream is a term sometimes used to those industry activities that fall between exploration and production (upstream) and refining and marketing (downstream). The term is most often applied to pipeline transportation of crude oil and natural gas. No authoritative reference available. false 11 Derivative loss related to purchased product costs 4 mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToProductCost mwe false credit duration Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of price risk... false false false false false false false false false false true negated false 1 false true false false 19996000 19996 false false false 2 false true false false 7816000 7816 false false false 3 false true false false 24993000 24993 false false false 4 false true false false 39954000 39954 false false false xbrli:monetaryItemType monetary Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of price risk derivatives not designated as hedging instruments. Purchased product costs gains and losses relate to contracts utilized to economically hedge costs. No authoritative reference available. false 12 Facility expenses 4 us-gaap_FacilityCosts us-gaap true debit duration No definition available. false false false false false false false false false false false terselabel false 1 false true false false 37934000 37934 false false false 2 false true false false 30165000 30165 false false false 3 false true false false 113266000 113266 false false false 4 false true false false 93945000 93945 false false false xbrli:monetaryItemType monetary Facility expenses incurred related to gas and oil produced and sold during the reporting period. No authoritative reference available. false 13 Derivative (gain) loss related to facility expenses 4 mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToFacilityExpense mwe false credit duration Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of price risk... false false false false false false false false false false true negated false 1 false true false false -564000 -564 false false false 2 false true false false 1347000 1347 false false false 3 false true false false -436000 -436 false false false 4 false true false false 122000 122 false false false xbrli:monetaryItemType monetary Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of price risk derivatives not designated as hedging instruments. Facility expense gains and losses relate to contracts utilized to economically hedge electricity costs for a facility. No authoritative reference available. false 14 Selling, general and administrative expenses 4 us-gaap_SellingGeneralAndAdministrativeExpense us-gaap true debit duration No definition available. false false false false false false false false false false false terselabel false 1 false true false false 17137000 17137 false false false 2 false true false false 15477000 15477 false false false 3 false true false false 55064000 55064 false false false 4 false true false false 46265000 46265 false false false xbrli:monetaryItemType monetary The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 4 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 43 -Chapter 4 -Paragraph 5A false 15 Depreciation 4 us-gaap_Depreciation us-gaap true debit duration No definition available. false false false false false false false false false false false terselabel false 1 false true false false 31362000 31362 false false false 2 false true false false 25264000 25264 false false false 3 false true false false 89367000 89367 false false false 4 false true false false 69621000 69621 false false false xbrli:monetaryItemType monetary The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 12 -Paragraph 5 false 16 Amortization of intangible assets 4 us-gaap_AmortizationOfIntangibleAssets us-gaap true debit duration No definition available. false false false false false false false false false false false terselabel false 1 false true false false 10193000 10193 false false false 2 false true false false 10193000 10193 false false false 3 false true false false 30579000 30579 false false false 4 false true false false 30638000 30638 false false false xbrli:monetaryItemType monetary The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by (used in) operations using the indirect method. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 142 -Paragraph 45 -Subparagraph a(2) false 17 Loss on disposal of property, plant and equipment 4 us-gaap_GainLossOnDispositionOfAssets us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false true false false 1937000 1937 false false false 2 false true false false 633000 633 false false false 3 false true false false 2116000 2116 false false false 4 false true false false 1432000 1432 false false false xbrli:monetaryItemType monetary The gains and losses included in earnings resulting from the sale or disposal of tangible assets. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 47 false 18 Accretion of asset retirement obligations 4 us-gaap_AssetRetirementObligationAccretionExpense us-gaap true debit duration No definition available. false false false false false false false false false false false terselabel false 1 false true false false 70000 70 false false false 2 false true false false 56000 56 false false false 3 false true false false 282000 282 false false false 4 false true false false 147000 147 false false false xbrli:monetaryItemType monetary Amount of accretion expense recognized in the income statement during the period that is associated with asset retirement obligations. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability. Such accretion expense representing changes in the liability for an asset retirement obligation due to passage of time is the result of applying an interest method of allocation to the amount of the liability at the beginning of the period. The interest rate used to measure that change shall be the credit-adjusted risk-free rate that existed when the liability, or portion thereof, was initially measured. That amount shall be recognized as an increase in the carrying amount of the liability and as an expense classified as an operating item in the statement of income. Accretion expense shall not be considered to be interest cost for purposes of capitalization of interest. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 143 -Paragraph 13, 14 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 143 -Paragraph 22 -Subparagraph c(3) false 19 Impairment of long-lived assets 4 us-gaap_AssetImpairmentCharges us-gaap true debit duration No definition available. false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false true false false 5855000 5855 false false false xbrli:monetaryItemType monetary The charge against earnings resulting from the aggregate write down of all assets from their carrying value to their fair value. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 45, 46, 47 false 20 Total operating expenses 4 us-gaap_CostsAndExpenses us-gaap true debit duration No definition available. false false false false false false false false false false false totallabel false 1 false true false false 254765000 254765 false false false 2 false true false false 182037000 182037 false false false 3 false true false false 724350000 724350 false false false 4 false true false false 562031000 562031 false false false xbrli:monetaryItemType monetary Total costs of sales and operating expenses for the period. No authoritative reference available. true 21 Income (loss) from operations 3 us-gaap_OperatingIncomeLoss us-gaap true credit duration No definition available. false false false false false false false false false false false totallabel false 1 false true false false 646000 646 false false false 2 false true false false 35654000 35654 false false false 3 false true false false 163290000 163290 false false false 4 false true false false -50904000 -50904 false false false xbrli:monetaryItemType monetary The net result for the period of deducting operating expenses from operating revenues. No authoritative reference available. true 22 Other income (expense): 3 us-gaap_NonoperatingIncomeExpenseAbstract us-gaap true na duration No definition available. false false false false false true false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false xbrli:stringItemType string No definition available. false 23 Earnings from unconsolidated affiliates 4 us-gaap_IncomeLossFromEquityMethodInvestments us-gaap true credit duration No definition available. false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false true false false 169000 169 false false false 3 false true false false 1517000 1517 false false false 4 false true false false 1260000 1260 false false false xbrli:monetaryItemType monetary This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. Such amount typically reflects adjustments similar to those made in preparing consolidated statements, including adjustments to eliminate intercompany gains and losses, and to amortize, if appropriate, any difference between cost and underlying equity in net assets of the investee at the date of investment. 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Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 14 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Article 5 false 25 Interest expense 4 us-gaap_InterestExpense us-gaap true debit duration No definition available. false false false false false false false false false false true negated false 1 false true false false -26433000 -26433 false false false 2 false true false false -23440000 -23440 false false false 3 false true false false -75970000 -75970 false false false 4 false true false false -63964000 -63964 false false false xbrli:monetaryItemType monetary The cost of borrowed funds accounted for as interest that was charged against earnings during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 34 -Paragraph 21 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher OTS -Name Federal Regulation (FR) -Number Title 12 -Chapter V -Section 563c.102 -Paragraph 9 -Subsection II Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 9 -Article 9 false 26 Amortization of deferred financing costs and discount (a component of interest expense) 4 us-gaap_AmortizationOfFinancingCostsAndDiscounts us-gaap true debit duration No definition available. false false false false false false false false false false true negated false 1 false true false false -3625000 -3625 false false false 2 false true false false -3091000 -3091 false false false 3 false true false false -8517000 -8517 false false false 4 false true false false -6528000 -6528 false false false xbrli:monetaryItemType monetary The component of interest expense representing the noncash expenses charged against earnings in the period to allocate debt discount and premium, and the costs to issue debt and obtain financing over the related debt instruments. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 false 27 Derivative gain related to interest expense 4 mwe_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRelatedToInterestExpense mwe false credit duration Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of price risk... false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false true false false 2265000 2265 false false false 3 false true false false 1871000 1871 false false false 4 false true false false 2265000 2265 false false false xbrli:monetaryItemType monetary Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of price risk derivatives not designated as hedging instruments. Interest expense gains and losses relate to changes in the fair value of interest rate swaps. No authoritative reference available. false 28 Miscellaneous income, net 4 us-gaap_OtherNonoperatingIncomeExpense us-gaap true credit duration No definition available. false false false false false false false false false false false terselabel false 1 false true false false 76000 76 false false false 2 false true false false 825000 825 false false false 3 false true false false 1129000 1129 false false false 4 false true false false 2546000 2546 false false false xbrli:monetaryItemType monetary The net amount of other nonoperating income and expense, which does not qualify for separate disclosure on the income statement under materiality guidelines. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 9 -Article 5 false 29 (Loss) income before provision for income tax 3 mwe_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest mwe false credit duration Sum of operating profit and nonoperating income (expense) before, income taxes, extraordinary items, cumulative effects of... false false false false false false false false false false false totallabel false 1 false true false false -28914000 -28914 false false false 2 false true false false 12482000 12482 false false false 3 false true false false 84505000 84505 false false false 4 false true false false -115124000 -115124 false false false xbrli:monetaryItemType monetary Sum of operating profit and nonoperating income (expense) before, income taxes, extraordinary items, cumulative effects of changes in accounting principles, and noncontrolling interest. No authoritative reference available. true 30 Provision for income tax (benefit) expense: 3 us-gaap_IncomeTaxExpenseBenefitAbstract us-gaap true na duration No definition available. false false false false false true false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false xbrli:stringItemType string No definition available. false 31 Current 4 us-gaap_CurrentIncomeTaxExpenseBenefit us-gaap true debit duration No definition available. false false false false false false false false false false false terselabel false 1 false true false false 3533000 3533 false false false 2 false true false false -46000 -46 false false false 3 false true false false 10254000 10254 false false false 4 false true false false 6530000 6530 false false false xbrli:monetaryItemType monetary The component of income tax expense for the period representing amounts of income taxes paid or payable (or refundable) for the period for all income tax obligations as determined by applying the provisions of relevant enacted tax laws to relevant amounts of taxable income (loss) from continuing operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 6 -Section I -Subsection 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 289 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph h -Article 4 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 45 -Subparagraph a false 32 Deferred 4 us-gaap_DeferredIncomeTaxExpenseBenefit us-gaap true debit duration No definition available. false false false false false false false false false false false terselabel false 1 false true false false -13771000 -13771 false false false 2 false true false false 624000 624 false false false 3 false true false false -45000 -45 false false false 4 false true false false -34693000 -34693 false false false xbrli:monetaryItemType monetary The component of income tax expense for the period representing the net change in the entity's deferred tax assets and liabilities pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 6 -Section I -Subsection 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 45 -Subparagraph b Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 289 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph h -Article 4 false 33 Total provision for income tax 4 us-gaap_IncomeTaxExpenseBenefit us-gaap true debit duration No definition available. false false false false false false false false false false false totallabel false 1 false true false false -10238000 -10238 false false false 2 false true false false 578000 578 false false false 3 false true false false 10209000 10209 false false false 4 false true false false -28163000 -28163 false false false xbrli:monetaryItemType monetary The sum of the current income tax expense (benefit) and the deferred income tax expense (benefit) pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph h -Article 4 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 45 -Subparagraph a, b true 34 Net (loss) income 3 us-gaap_ProfitLoss us-gaap true credit duration No definition available. false false false false false false false false false false false totallabel false 1 false true false false -18676000 -18676 false false false 2 false true false false 11904000 11904 false false false 3 false true false false 74296000 74296 false false false 4 false true false false -86961000 -86961 false false false xbrli:monetaryItemType monetary The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph A1, A4, A5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 5 -Subparagraph b Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 29 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph a Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph c(1) true 35 Net income attributable to non-controlling interest 3 us-gaap_NetIncomeLossAttributableToNoncontrollingInterest us-gaap true debit duration No definition available. false false false false false false false false false false true negated false 1 false true false false -8475000 -8475 false false false 2 false true false false -3624000 -3624 false false false 3 false true false false -19720000 -19720 false false false 4 false true false false -1914000 -1914 false false false xbrli:monetaryItemType monetary The portion of net income (loss) attributable to the noncontrolling interest (if any) deducted in order to derive the portion attributable to the parent. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph a Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph c(1) Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph A1, A4, A5 false 36 Net (loss) income attributable to the Partnership 3 us-gaap_NetIncomeLossAllocatedToLimitedPartners us-gaap true credit duration No definition available. false false false false false false false false false false false totallabel false 1 true true false false -27151000 -27151 false false false 2 true true false false 8280000 8280 false false false 3 true true false false 54576000 54576 false false false 4 true true false false -88875000 -88875 false false false xbrli:monetaryItemType monetary Aggregate amount of net income allocated to general partners in a publicly trade limited partnership or master limited partnership (MLP). Limited partners have limited liability and do not manage the partnership. No authoritative reference available. true 37 Net (loss) income attributable to the Partnership's common unitholders per common unit (Note 12): 3 us-gaap_EarningsPerUnitAbstract us-gaap true na duration No definition available. false false false false false true false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false xbrli:stringItemType string No definition available. false 38 Basic (in dollars per unit) 4 us-gaap_NetIncomeLossPerOutstandingLimitedPartnershipUnit us-gaap true na duration No definition available. false false false false false false false false false false false terselabel true 1 true true false false -0.39 -0.39 false false false 2 true true false false 0.13 0.13 false false false 3 true true false false 0.77 0.77 false false false 4 true true false false -1.52 -1.52 false false false us-types:perUnitItemType decimal Net income (loss) allocated to each outstanding limited partnership unit in a publicly traded limited partnership or master limited partnership (MLP). Limited partners have limited liability and do not manage the partnership. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 4 -Section F false 39 Diluted (in dollars per unit) 4 us-gaap_NetIncomeLossPerOutstandingLimitedPartnershipUnitDiluted us-gaap true na duration No definition available. false false false false false false false false false false false terselabel true 1 true true false false -0.39 -0.39 false false false 2 true true false false 0.13 0.13 false false false 3 true true false false 0.77 0.77 false false false 4 true true false false -1.52 -1.52 false false false us-types:perUnitItemType decimal Net income (loss) allocated to each limited partner unit outstanding during the reporting period and each unit that would have been outstanding assuming the issuance of limited partner units for all dilutive potential units outstanding during the reporting period. Limited partners have limited liability and do not manage the partnership. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 4 -Section F false 40 Weighted average number of outstanding common units: 3 mwe_WeightedAverageNumberOfOutstandingCommonUnitsAbstract mwe false na duration No definition available. false false false false false true false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false xbrli:stringItemType string No definition available. false 41 Basic (in units) 4 us-gaap_WeightedAverageLimitedPartnershipUnitsOutstanding us-gaap true na duration No definition available. false false false false false false false false false false false terselabel false 1 false true false false 71438000 71438 false false false 2 false true false false 63026000 63026 false false false 3 false true false false 69685000 69685 false false false 4 false true false false 59168000 59168 false false false xbrli:sharesItemType shares Weighted average number of limited partnership units outstanding determined by relating the portion of time within a reporting period that limited partnership units have been outstanding to the total time in that period. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 4 -Section F false 42 Diluted (in units) 4 us-gaap_WeightedAverageLimitedPartnershipUnitsOutstandingDiluted us-gaap true na duration No definition available. false false false false false false false false false false false terselabel false 1 false true false false 71438000 71438 false false false 2 false true false false 63026000 63026 false false false 3 false true false false 69831000 69831 false false false 4 false true false false 59168000 59168 false false false xbrli:sharesItemType shares Weighted average number of limited partnership units outstanding determined by relating the portion of time within a reporting period that limited partnership units have been outstanding to the total time in that period. Used in the calculation of diluted net income (loss) per limited partnership unit. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 4 -Section F false 43 Cash distribution declared per common unit (in dollars per unit) 3 us-gaap_DistributionsPerLimitedPartnershipUnitOutstanding us-gaap true na duration No definition available. false false false false false false false false false false false terselabel true 1 true true false false 0.64 0.64 false false false 2 true true false false 0.64 0.64 false false false 3 true true false false 1.92 1.92 false false false 4 true true false false 1.92 1.92 false false false us-types:perShareItemType decimal Cash dividends declared or paid to each outstanding limited partnership unit of a publicly traded limited partnership or master limited partnership (MLP) during the reporting period. Limited partners have limited liability and do not manage the partnership. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 4 -Section F false 4 39 false Thousands Thousands NoRounding false true