2.4.0.8040070 - Disclosure - Commitments and Contingencies (Details-1)truefalseIn Millions, unless otherwise specifiedfalse1false USDfalsefalse$FROM_Jan01_2013_TO_Jun30_2013http://www.sec.gov/CIK0001161728duration2013-01-01T00:00:002013-06-30T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 2mgee_ColumbiaCleanAirActLitigationAbstractmgee_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Columbia Clean Air Act Litigation [Abstract]2false 3mgee_ColumbiaCleanAirActLitigationCivilPenaltiesmgee_falsedebitdurationfalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse2000000.2USD$falsetruefalsexbrli:monetaryItemTypemonetaryThis element represents the expenses incurred by the entity which are directly related to settlement of litigation.No definition available.false2Columbia Clean Air Act litigation civil penalties3false 3mgee_ColumbiaCleanAirActLitigationEnvironmentalMitigationCostsmgee_falsedebitinstantfalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse6000000.6USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThis element represents the approximate costs of environmental mitigation projects agreed to in the terms of the final consent decree.No definition available.false2Columbia Clean Air Act litigation environmental mitigation costs4false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2false USDtruefalse$FROM_Jan01_2013_TO_Jun30_2013_mgee_ConstructionProjectAxis_ColumbiaEnvironmentalProjectMemberhttp://www.sec.gov/CIK0001161728duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseColumbia Environmental Project [Member]mgee_ConstructionProjectAxisxbrldihttp://xbrl.org/2006/xbrldimgee_ColumbiaEnvironmentalProjectMembermgee_ConstructionProjectAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Columbia Environmental Project [Member]5true 3mgee_ExpectedCapitalExpendituresLineItemsmgee_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Expected Capital Expenditures [Line Items]6false 4mgee_ExpectedCapitalExpendituresmgee_falsedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse140000000140.0USD$falsefalsefalsexbrli:monetaryItemTypemonetaryExpected capital expenditures to be incurred during construction of an asset.No definition available.false2MGE's total share of expected capital expenditures7true 4mgee_ColumbiaCommitmentsAbstractmgee_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Columbia Commitments [Abstract]8false 5mgee_ColumbiaEnvironmentalProjectCommitmentsmgee_falsecreditinstantfalsefalsefalsefalsefalsefalsefalsefalse1truefalsefalse3860000038.6USD$falsetruefalsexbrli:monetaryItemTypemonetaryCommitted Columbia environmental project commitments.No definition available.false2Columbia environmental project commitments9false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse3false truefalseAS_OF_Jun30_2013_us-gaap_JointlyOwnedUtilityPlantAxis_ColumbiaUnitsMemberhttp://www.sec.gov/CIK0001161728instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseColumbia Units [Member]us-gaap_JointlyOwnedUtilityPlantAxisxbrldihttp://xbrl.org/2006/xbrldimgee_ColumbiaUnitsMemberus-gaap_JointlyOwnedUtilityPlantAxisexplicitMemberMWStandardhttp://www.xbrl.org/2009/utrMWutr0PureStandardhttp://www.xbrl.org/2003/instancepurexbrli0nanafalse0Columbia Units [Member]10true 3us-gaap_JointlyOwnedUtilityPlantInterestsLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Jointly Owned Utility Plant Interests [Line Items]11false 4mgee_JointlyOwnedUtilityPlantMegawattCapacityMgemgee_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse225225falsefalsefalsenum:powerItemTypedecimalMGE's portion of the total operating capacity (in MWs) of each of the two units in the jointly owned utility plant.No definition available.false256Generating capability - MW12false 4mgee_JointlyOwnedUtilityPlantFacilityShareOfMgeNetGeneratingCapabilitymgee_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.290.29falsefalsefalsenum:percentItemTypepureA jointly owned utility plant's share of MGE's net generating capability.No definition available.false0Columbia's share of MGE's net generating capability13false 4us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShareus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.220.22falsefalsefalsenum:percentItemTypepureThe proportionate share of interest (percent) in a jointly owned utility plant.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 10.C) -URI http://asc.fasb.org/extlink&oid=6500719&loc=d3e659983-123033 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 10 -Section C false0Ownership interest in jointly owned plant14false 4mgee_JointlyOwnedUtilityPlantProportionateOwnershipShareWplmgee_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.4620.462falsefalsefalsenum:percentItemTypepureWPL's proportionate share of interest (percent) in Columbia, a jointly owned utility plant.No definition available.false0WPL ownership interest of Columbia15false 4mgee_JointlyOwnedUtilityPlantProportionateOwnershipShareWpscmgee_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.3180.318falsefalsefalsenum:percentItemTypepureWPSC's proportionate share of interest (percent) in Columbia, a jointly owned utility plant.No definition available.false0WPSC ownership interest of ColumbiafalseCommitments and Contingencies (Details-1) (USD $)HundredThousandsUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.mgeenergy.com/role/DisclosureCommitmentsAndContingenciesDetails1115