2.4.0.84110 - Disclosure - Equity (Details)truefalseShare data in Thousands, except Per Share data, unless otherwise specifiedfalse1false USDfalsefalse$D2013Q2http://www.sec.gov/CIK0001166036duration2013-04-01T00:00:002013-06-30T00:00:00USDPerShareDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2false USDfalsefalse$D2013Q1http://www.sec.gov/CIK0001166036duration2013-01-01T00:00:002013-03-31T00:00:00USDPerShareDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$3false USDfalsefalse$D2012Q4http://www.sec.gov/CIK0001166036duration2012-10-01T00:00:002012-12-31T00:00:00USDPerShareDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$4false USDfalsefalse$D2013Q2YTDhttp://www.sec.gov/CIK0001166036duration2013-01-01T00:00:002013-06-30T00:00:00SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$5false USDfalsefalse$D2012Q2YTDhttp://www.sec.gov/CIK0001166036duration2012-01-01T00:00:002012-06-30T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 2us-gaap_PartnersCapitalAccountUnitsSaleOfUnitsAbstractus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Equity Offerings2false 3us-gaap_PartnersCapitalAccountUnitsSoldInPublicOfferingus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4truefalsefalse57000005700falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:sharesItemTypesharesThe number of units sold in a public offering of each class of partners' capital account. Units represent shares of ownership of the general, limited, and preferred partners.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 5 -Subparagraph (SAB TOPIC 4.F) -URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187171-122770 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Emerging Issues Task Force (EITF) -Number 87-21 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Practice Bulletin (PB) -Number 14 -Paragraph 15 -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. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 16 -Subparagraph a, b -Article 6 false1Aggregate common units sold under ATM (in units)3false 3us-gaap_ProceedsFromIssuanceOfCommonLimitedPartnersUnitsus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4truefalsefalse348352000348352000USD$falsetruefalse5truefalsefalse852873000852873000USD$falsetruefalsexbrli:monetaryItemTypemonetaryThe cash inflow from the issuance of common limited partners units during the period.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Financing Activities -URI http://asc.fasb.org/extlink&oid=6513228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3255-108585 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 19 -Subparagraph a -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Proceeds from public equity offerings, net4false 3mwe_ManagerFeesInConnectionWithIssuancesOfCommonUnitmwe_falsedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4truefalsefalse52000005200000USD$falsetruefalse5falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryRepresents the amount of fees paid or payable to manager for acting as sales agent in connection with the issuances of common units under the continuous equity offering program.No definition available.false2Manager fees5true 2us-gaap_DistributionsMadeToMembersOrLimitedPartnersAbstractus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Distributions of Available Cash6false 3us-gaap_DistributionMadeToMemberOrLimitedPartnerDistributionsDeclaredPerUnitus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse0.840.84USD$falsetruefalse2truefalsefalse0.830.83USD$falsetruefalse3truefalsefalse0.820.82USD$falsetruefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalsenum:perShareItemTypedecimalPer-share or per-unit cash distributions declared to a common shareholder or unit-holder by an LLC or LP.No definition available.false3Distribution per common unit (in dollars per unit)7false 3us-gaap_DistributionMadeToMemberOrLimitedPartnerDeclarationDate1us-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse002013-07-24falsefalsetrue2falsefalsefalse002013-04-25falsefalsetrue3falsefalsefalse002013-01-23falsefalsetrue4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:dateItemTypedateDate of declaration for distribution of cash, stock, or units to a member or limited partner of limited liability company (LLC) or limited partnership (LP), in CCYY-MM-DD format.No definition available.false0Declaration Date8false 3us-gaap_DistributionMadeToMemberOrLimitedPartnerDateOfRecord1us-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse002013-08-06falsefalsetrue2falsefalsefalse002013-05-07falsefalsetrue3falsefalsefalse002013-02-06falsefalsetrue4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:dateItemTypedateDate of record for distribution of cash, stock, or units to a member or limited partner of limited liability company (LLC) or limited partnership (LP), in CCYY-MM-DD format.No definition available.false0Record Date9false 3us-gaap_DistributionMadeToMemberOrLimitedPartnerDistributionDate1us-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse002013-08-14falsefalsetrue2falsefalsefalse002013-05-15falsefalsetrue3falsefalsefalse002013-02-14falsefalsetrue4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:dateItemTypedateDate of distribution for distribution of cash, stock, or units to a member or limited partner of limited liability company (LLC) or limited partnership (LP), in CCYY-MM-DD format.No definition available.false0Payment Date10false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6false USDtruefalse$I2013Q2_MinimumMemberhttp://www.sec.gov/CIK0001166036instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseMinimumus-gaap_RangeAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_MinimumMemberus-gaap_RangeAxisexplicitMemberUSDPerShareDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$nanafalse0Minimum11true 3us-gaap_ClassOfStockLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Equity12false 4us-gaap_SharePriceus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse56.9056.90USD$falsetruefalse2truefalsefalse51.7751.77USD$falsetruefalse3truefalsefalse46.0346.03USD$falsetruefalse4truefalsefalse56.9056.90USD$falsetruefalse5falsefalsefalse00falsefalsefalsenum:perShareItemTypedecimalPrice of a single share of a number of saleable stocks of a company.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 false3Common Unit Price (in dollars per share)13false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse9false USDtruefalse$I2013Q2_MaximumMemberhttp://www.sec.gov/CIK0001166036instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseMaximumus-gaap_RangeAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_MaximumMemberus-gaap_RangeAxisexplicitMemberUSDPerShareDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$nanafalse0Maximum14true 3us-gaap_ClassOfStockLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Equity15false 4us-gaap_SharePriceus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse71.2071.20USD$falsetruefalse2truefalsefalse61.9761.97USD$falsetruefalse3truefalsefalse55.9555.95USD$falsetruefalse4truefalsefalse71.2071.20USD$falsetruefalse5falsefalsefalse00falsefalsefalsenum:perShareItemTypedecimalPrice of a single share of a number of saleable stocks of a company.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 false3Common Unit Price (in dollars per share)falseEquity (Details) (USD $)NoRoundingThousandsNoRoundingUnKnowntruefalsefalseSheethttp://www.markwest.com/role/DisclosureEquityDetails515