$MGEE
MGE ENERGY INC Stock $mgee

$mgee Overview Financials Valuation SEC Filings Company Website

2018 Q4 Form 10-Q Financial Statement

#000116172818000035 Filed on November 06, 2018

Income Statement

Concept	2018 Q4	2018 Q3	2017 Q4
Revenue	$140.1M	$137.8M	$140.3M
YoY Change	-0.14%	-1.25%	0.97%
Cost Of Revenue	$38.60M	$17.90M	$37.20M
YoY Change	3.76%	-15.17%	-9.49%
Gross Profit	$101.5M	$119.9M	$103.1M
YoY Change	-1.55%	1.27%	5.42%
Gross Profit Margin	72.46%	87.01%	73.5%
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$14.60M	$14.30M	$13.50M
YoY Change	8.15%	6.72%	20.54%
% of Gross Profit	14.38%	11.93%	13.09%
Operating Expenses	$77.50M	$80.10M	$77.90M
YoY Change	-0.51%	4.84%	5.41%
Operating Profit	$23.99M	$39.80M	$25.20M
YoY Change	-4.79%	-5.24%	5.17%
Interest Expense	-$5.100M	-$5.000M	-$4.800M
YoY Change	6.25%	6.38%	-2.04%
% of Operating Profit	-21.26%	-12.56%	-19.05%
Other Income/Expense, Net	$3.100M	$4.330M	$2.400M
YoY Change	29.17%	-12.4%	-20.0%
Pretax Income	$22.00M	$39.10M	$22.70M
YoY Change	-3.08%	-7.37%	2.71%
Income Tax	$5.642M	$9.597M	-$13.39M
% Of Pretax Income	25.65%	24.54%	-59.0%
Net Earnings	$16.36M	$29.51M	$36.13M
YoY Change	-54.72%	10.8%	149.17%
Net Earnings / Revenue	11.68%	21.41%	25.76%
Basic Earnings Per Share
Diluted Earnings Per Share	$472.6K	$850.1K	$1.040M
COMMON SHARES
Basic Shares Outstanding	34.67M shares	34.67M shares	34.67M shares
Diluted Shares Outstanding

Balance Sheet

Concept	2018 Q4	2018 Q3	2017 Q4
SHORT-TERM ASSETS
Cash & Short-Term Investments	$83.10M	$133.9M	$108.0M
YoY Change	-23.06%	27.89%	12.5%
Cash & Equivalents	$83.10M	$133.9M	$108.0M
Short-Term Investments
Other Short-Term Assets	$8.593M	$52.10M	$12.51M
YoY Change	-31.29%	-10.63%	1.74%
Inventory	$42.00M	$45.40M	$43.80M
Prepaid Expenses
Receivables	$43.59M	$41.69M	$42.30M
Other Receivables	$6.262M	$7.565M	$9.440M
Total Short-Term Assets	$240.6M	$280.7M	$290.6M
YoY Change	-17.23%	9.91%	5.49%
LONG-TERM ASSETS
Property, Plant & Equipment	$1.509B	$1.459B	$1.341B
YoY Change	12.53%	11.21%	4.63%
Goodwill
YoY Change
Intangibles
YoY Change
Long-Term Investments	$66.34M	$73.40M	$20.40M
YoY Change	225.19%	-15.14%	-72.29%
Other Assets	$12.49M	$8.729M	$731.0K
YoY Change	1608.34%	-94.4%	-32.81%
Total Long-Term Assets	$1.748B	$1.694B	$1.565B
YoY Change	11.73%	8.94%	2.56%
TOTAL ASSETS
Total Short-Term Assets	$240.6M	$280.7M	$290.6M
Total Long-Term Assets	$1.748B	$1.694B	$1.565B
Total Assets	$1.989B	$1.974B	$1.855B
YoY Change	7.19%	9.08%	3.01%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$46.16M	$50.34M	$47.65M
YoY Change	-3.12%	59.81%	-0.32%
Accrued Expenses	$20.40M	$16.40M	$17.80M
YoY Change	14.61%	11.56%	2.3%
Deferred Revenue
YoY Change
Short-Term Debt	$13.00M	$0.00	$4.000M
YoY Change	225.0%	-100.0%
Long-Term Debt Due	$4.553M	$4.527M	$24.45M
YoY Change	-81.38%	2.89%	464.32%
Total Short-Term Liabilities	$120.6M	$98.49M	$126.5M
YoY Change	-4.65%	16.44%	22.23%
LONG-TERM LIABILITIES
Long-Term Debt	$493.3M	$494.4M	$398.2M
YoY Change	23.91%	26.96%	4.02%
Other Long-Term Liabilities	$66.36M	$72.06M	$69.04M
YoY Change	-3.88%	12.7%	3.94%
Total Long-Term Liabilities	$558.0M	$569.4M	$552.3M
YoY Change	1.03%	-2.29%	-6.49%
TOTAL LIABILITIES
Total Short-Term Liabilities	$120.6M	$98.49M	$126.5M
Total Long-Term Liabilities	$558.0M	$569.4M	$552.3M
Total Liabilities	$678.6M	$667.9M	$678.8M
YoY Change	-0.03%	0.09%	-2.21%
SHAREHOLDERS EQUITY
Retained Earnings	$465.7M		$426.9M
YoY Change	9.1%		14.46%
Common Stock	$34.67M		$34.67M
YoY Change	0.0%		0.0%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$816.6M	$812.0M	$778.2M
YoY Change
Total Liabilities & Shareholders Equity	$1.989B	$1.974B	$1.855B
YoY Change	7.19%	9.08%	3.01%

Cashflow Statement

Concept	2018 Q4	2018 Q3	2017 Q4
OPERATING ACTIVITIES
Net Income	$16.36M	$29.51M	$36.13M
YoY Change	-54.72%	10.8%	149.17%
Depreciation, Depletion And Amortization	$14.60M	$14.30M	$13.50M
YoY Change	8.15%	6.72%	20.54%
Cash From Operating Activities	$14.60M	$46.80M	$35.30M
YoY Change	-58.64%	60.82%	92.9%
INVESTING ACTIVITIES
Capital Expenditures	-$63.20M	-$48.60M	-$41.80M
YoY Change	51.2%	101.66%	95.33%
Acquisitions
YoY Change
Other Investing Activities	-$1.700M	-$1.700M	-$3.800M
YoY Change	-55.26%	-525.0%	322.22%
Cash From Investing Activities	-$64.90M	-$50.30M	-$45.70M
YoY Change	42.01%	112.24%	105.86%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	200.0K	38.30M	14.50M
YoY Change	-98.62%	-822.64%	-223.93%
NET CHANGE
Cash From Operating Activities	14.60M	46.80M	35.30M
Cash From Investing Activities	-64.90M	-50.30M	-45.70M
Cash From Financing Activities	200.0K	38.30M	14.50M
Net Change In Cash	-50.10M	34.80M	4.100M
YoY Change	-1321.95%	34700.0%	-126.28%
FREE CASH FLOW
Cash From Operating Activities	$14.60M	$46.80M	$35.30M
Capital Expenditures	-$63.20M	-$48.60M	-$41.80M
Free Cash Flow	$77.80M	$95.40M	$77.10M
YoY Change	0.91%	79.32%	94.21%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2017Q4	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	42299000	USD
CY2018Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-5025000	USD
CY2018Q3	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	4330000	USD
CY2017Q3	us-gaap	Utilities Operating Expense UtilitiesOperatingExpense	97542000	USD
CY2017Q4	us-gaap	Other Receivables Net Current OtherReceivablesNetCurrent	9440000	USD
CY2017Q4	us-gaap	Other Inventory Supplies OtherInventorySupplies	22614000	USD
CY2017Q4	us-gaap	Energy Related Inventory Other Fossil Fuel EnergyRelatedInventoryOtherFossilFuel	8256000	USD
CY2017Q4	us-gaap	Energy Related Inventory Gas Stored Underground EnergyRelatedInventoryGasStoredUnderground	12923000	USD
CY2017Q4	us-gaap	Prepaid Taxes PrepaidTaxes	26535000	USD
CY2017Q4	us-gaap	Regulatory Assets Current RegulatoryAssetsCurrent	7888000	USD
CY2017Q4	us-gaap	Other Assets Current OtherAssetsCurrent	12507000	USD
CY2017Q4	us-gaap	Assets Current AssetsCurrent	290631000	USD
CY2017Q4	us-gaap	Regulatory Assets Noncurrent RegulatoryAssetsNoncurrent	142567000	USD
CY2017Q4	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	731000	USD
CY2017Q4	mgee	Property Plant And Equipment Net Before Construction In Progress PropertyPlantAndEquipmentNetBeforeConstructionInProgress	1283313000	USD
CY2017Q4	us-gaap	Construction In Progress Gross ConstructionInProgressGross	58044000	USD
CY2017Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	1341357000	USD
CY2017Q4	us-gaap	Investments Investments	67772000	USD
CY2017Q4	us-gaap	Assets Assets	1855182000	USD
CY2017Q4	us-gaap	Long Term Debt Current LongTermDebtCurrent	24452000	USD
CY2017Q4	us-gaap	Accounts Payable Current AccountsPayableCurrent	47645000	USD
CY2017Q4	us-gaap	Derivative Liabilities Current DerivativeLiabilitiesCurrent	8180000	USD
CY2017Q4	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	18758000	USD
CY2017Q4	us-gaap	Liabilities Current LiabilitiesCurrent	126514000	USD
CY2017Q4	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	225130000	USD
CY2017Q4	us-gaap	Accumulated Deferred Investment Tax Credit AccumulatedDeferredInvestmentTaxCredit	918000	USD
CY2017Q4	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	154153000	USD
CY2017Q4	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	69088000	USD
CY2017Q4	us-gaap	Derivative Liabilities Noncurrent DerivativeLiabilitiesNoncurrent	33990000	USD
CY2017Q4	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	69041000	USD
CY2017Q4	us-gaap	Liabilities Noncurrent LiabilitiesNoncurrent	552320000	USD
CY2017Q4	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	398161000	USD
CY2017Q4	us-gaap	Capitalization Longterm Debt And Equity CapitalizationLongtermDebtAndEquity	1176348000	USD
CY2017Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	1855182000	USD
	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	0	shares
	us-gaap	Derivatives Methods Of Accounting Hedging Derivatives DerivativesMethodsOfAccountingHedgingDerivatives	<div><p style='text-align:left;margin-top:0pt;margin-bottom:0pt;line-height:12pt;' ><font style='font-family:Times New Roman;font-size:10pt;margin-left:45pt;' >As </font><font style='font-family:Times New Roman;font-size:10pt;' >part </font><font style='font-family:Times New Roman;font-size:10pt;' >of its regular operations, MGE enters into contracts, including options, swaps, futures, forwards, and other contractual commitments, to manage its exposure to commodity prices. To the extent that these contracts are derivatives, MGE assesses whether or no</font><font style='font-family:Times New Roman;font-size:10pt;' >t the normal purchases or normal sales exclusion applies. For contracts to which this exclusion cannot be applied, the derivatives are recognized in the consolidated balance sheets at fair value. MGE's financial commodity derivative activities are conducte</font><font style='font-family:Times New Roman;font-size:10pt;' >d in accordance with its electric and gas risk management program, which is approved by the PSCW and limits the volume MGE can hedge with specific risk management strategies. The maximum length of time over which cash flows related to energy commodities ca</font><font style='font-family:Times New Roman;font-size:10pt;' >n be hedged is four years. If the derivative qualifies for regulatory deferral, the derivatives are marked to fair value and are offset with a corresponding regulatory asset or liability depending on whether the derivative is in a net</font><font style='font-family:Times New Roman;font-size:10pt;' > loss or net gain posi</font><font style='font-family:Times New Roman;font-size:10pt;' >tion, respectively. The deferred gain or loss is recognized in earnings in the delivery month applicable to the instrument. Gains and losses related to hedges qualifying for regulatory treatment are recoverable in gas rates through the PGA or in electric r</font><font style='font-family:Times New Roman;font-size:10pt;' >ates as a component of the fuel rules mechanism</font><font style='font-family:Times New Roman;font-size:10pt;' >. </font></p></div>
	mgee	Fair Value Inputs Delivery Points Basis Adjustment On Peak FairValueInputsDeliveryPointsBasisAdjustmentOnPeak	0.919	pure
	mgee	Fair Value Inputs Delivery Points Basis Adjustment Off Peak FairValueInputsDeliveryPointsBasisAdjustmentOffPeak	0.932	pure
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	127000	USD
CY2016Q4	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis With Unobservable Inputs FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs	-50305000	USD
	mgee	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Regulatory Liabilities Assets FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInRegulatoryLiabilitiesAssets	7547000	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Other Comprehensive Income Loss FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInOtherComprehensiveIncomeLoss	0	USD
	mgee	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Current Assets FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInCurrentAssets	-111000	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Purchases FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases	18481000	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Sales FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSales	0	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Issues FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues	0	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Settlements FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements	15757000	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Transfers Net FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersNet	0	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Change In Unrealized Gain Loss FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainLoss	0	USD
CY2018Q3	mgee	Counterparties In Default CounterpartiesInDefault	0
	mgee	Utilities Operating Expense Excluding Depreciation And Amortization UtilitiesOperatingExpenseExcludingDepreciationAndAmortization	283791000	USD
CY2017Q4	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	12244000	USD
CY2017Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
	us-gaap	Utilities Operating Expense Fuel Used UtilitiesOperatingExpenseFuelUsed	39938000	USD
	us-gaap	Utilities Operating Expense Purchased Power UtilitiesOperatingExpensePurchasedPower	48058000	USD
	mgee	Utilities Operating Expense Cost Of Gas Sold UtilitiesOperatingExpenseCostOfGasSold	50109000	USD
	us-gaap	Utilities Operating Expense Maintenance And Operations UtilitiesOperatingExpenseMaintenanceAndOperations	131177000	USD
	us-gaap	Utilities Operating Expense Taxes UtilitiesOperatingExpenseTaxes	14509000	USD
CY2018Q3	us-gaap	Other Liabilities Noncurrent OtherLiabilitiesNoncurrent	72064000	USD
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	0	USD
	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	2352000	USD
	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	642000	USD
	us-gaap	Earnings Per Share Basic And Diluted EarningsPerShareBasicAndDiluted	1.77
	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.938
	us-gaap	Weighted Average Number Of Share Outstanding Basic And Diluted WeightedAverageNumberOfShareOutstandingBasicAndDiluted	34668000	shares
	us-gaap	Utilities Operating Expense Fuel Used UtilitiesOperatingExpenseFuelUsed	43944000	USD
	us-gaap	Utilities Operating Expense Purchased Power UtilitiesOperatingExpensePurchasedPower	43036000	USD
	mgee	Utilities Operating Expense Cost Of Gas Sold UtilitiesOperatingExpenseCostOfGasSold	54109000	USD
	us-gaap	Utilities Operating Expense Maintenance And Operations UtilitiesOperatingExpenseMaintenanceAndOperations	131976000	USD
	us-gaap	Utilities Operating Expense Taxes UtilitiesOperatingExpenseTaxes	14653000	USD
	us-gaap	Utilities Operating Expense UtilitiesOperatingExpense	329472000	USD
	us-gaap	Earnings Per Share Basic And Diluted EarningsPerShareBasicAndDiluted	1.96
	us-gaap	Weighted Average Number Of Share Outstanding Basic And Diluted WeightedAverageNumberOfShareOutstandingBasicAndDiluted	34668000	shares
	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	0	USD
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	67858000	USD
	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	-1544000	USD
	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-31000	USD
	us-gaap	Increase Decrease In Other Current Liabilities IncreaseDecreaseInOtherCurrentLiabilities	6026000	USD
	us-gaap	Pension And Other Postretirement Benefit Contributions PensionAndOtherPostretirementBenefitContributions	3967000	USD
	us-gaap	Increase Decrease In Other Noncurrent Assets And Liabilities Net IncreaseDecreaseInOtherNoncurrentAssetsAndLiabilitiesNet	-527000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	138432000	USD
	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-368000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-153434000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	34062000	USD
	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	23330000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	37949000	USD
CY2018Q3	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		USD
CY2018Q3	us-gaap	Accounts Receivable Net Current AccountsReceivableNetCurrent	41693000	USD
CY2018Q3	us-gaap	Other Receivables Net Current OtherReceivablesNetCurrent	7565000	USD
CY2018Q3	us-gaap	Other Assets Noncurrent OtherAssetsNoncurrent	8729000	USD
CY2018Q3	mgee	Property Plant And Equipment Net Before Construction In Progress PropertyPlantAndEquipmentNetBeforeConstructionInProgress	1350253000	USD
CY2018Q3	us-gaap	Construction In Progress Gross ConstructionInProgressGross	109209000	USD
CY2018Q3	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	1459462000	USD
CY2018Q3	us-gaap	Investments Investments	73445000	USD
CY2018Q3	us-gaap	Long Term Debt Current LongTermDebtCurrent	4527000	USD
CY2018Q3	us-gaap	Accounts Payable Current AccountsPayableCurrent	50340000	USD
CY2018Q3	us-gaap	Employee Related Liabilities Current EmployeeRelatedLiabilitiesCurrent	10879000	USD
CY2018Q3	us-gaap	Derivative Liabilities Current DerivativeLiabilitiesCurrent	9350000	USD
CY2018Q3	us-gaap	Other Liabilities Current OtherLiabilitiesCurrent	10509000	USD
CY2018Q3	us-gaap	Liabilities Current LiabilitiesCurrent	98489000	USD
CY2018Q3	us-gaap	Deferred Tax Liabilities Noncurrent DeferredTaxLiabilitiesNoncurrent	229197000	USD
CY2018Q3	us-gaap	Accumulated Deferred Investment Tax Credit AccumulatedDeferredInvestmentTaxCredit	843000	USD
CY2018Q3	us-gaap	Regulatory Liability Noncurrent RegulatoryLiabilityNoncurrent	171057000	USD
CY2018Q3	us-gaap	Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent	69346000	USD
CY2018Q3	us-gaap	Derivative Liabilities Noncurrent DerivativeLiabilitiesNoncurrent	26920000	USD
CY2018Q3	us-gaap	Capitalization Longterm Debt And Equity CapitalizationLongtermDebtAndEquity	1306381000	USD
CY2018Q3	us-gaap	Liabilities Noncurrent LiabilitiesNoncurrent	569427000	USD
CY2018Q3	us-gaap	Long Term Debt Noncurrent LongTermDebtNoncurrent	494398000	USD
CY2018Q3	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	1974297000	USD
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	189000	USD
	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	34062000	USD
	dei	Document Period End Date DocumentPeriodEndDate	2018-09-30
	dei	Amendment Flag AmendmentFlag	false
	dei	Entity Registrant Name EntityRegistrantName	MGE Energy Inc
	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2018Q4	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	34668370	shares
	mgee	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Regulatory Liabilities Assets FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInRegulatoryLiabilitiesAssets	6711000	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Other Comprehensive Income Loss FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInOtherComprehensiveIncomeLoss	0	USD
	mgee	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Current Assets FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInCurrentAssets	-496000	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Purchases FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases	17602000	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Sales FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSales	0	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Issues FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues	0	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Settlements FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements	16671000	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Transfers Net FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersNet	0	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Change In Unrealized Gain Loss FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainLoss	0	USD
	mgee	Utilities Operating Expense Excluding Depreciation And Amortization UtilitiesOperatingExpenseExcludingDepreciationAndAmortization	287718000	USD
CY2018Q3	mgee	Accruedinterestandtaxes Accruedinterestandtaxes	5554000	USD
CY2017Q4	mgee	Accruedinterestandtaxes Accruedinterestandtaxes	5602000	USD
	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.983
CY2017	mgee	Fair Value Inputs Delivery Points Basis Adjustment On Peak FairValueInputsDeliveryPointsBasisAdjustmentOnPeak	0.923	pure
CY2017	mgee	Fair Value Inputs Delivery Points Basis Adjustment Off Peak FairValueInputsDeliveryPointsBasisAdjustmentOffPeak	0.941	pure
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	149001000	USD
CY2018Q3	us-gaap	Assets Assets	1974297000	USD
CY2017Q4	us-gaap	Derivative Net Liability Position Aggregate Fair Value DerivativeNetLiabilityPositionAggregateFairValue	100000	USD
CY2018Q3	us-gaap	Derivative Net Liability Position Aggregate Fair Value DerivativeNetLiabilityPositionAggregateFairValue	0	USD
CY2018Q3	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	2416000	USD
CY2017Q4	us-gaap	Allowance For Doubtful Accounts Receivable Current AllowanceForDoubtfulAccountsReceivableCurrent	2840000	USD
CY2018Q3	us-gaap	Allowance For Doubtful Accounts Premiums And Other Receivables AllowanceForDoubtfulAccountsPremiumsAndOtherReceivables	571000	USD
CY2017Q4	us-gaap	Allowance For Doubtful Accounts Premiums And Other Receivables AllowanceForDoubtfulAccountsPremiumsAndOtherReceivables	335000	USD
	dei	Trading Symbol TradingSymbol	MGEE
	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	4810000	USD
	us-gaap	Provision For Doubtful Accounts ProvisionForDoubtfulAccounts	650000	USD
	us-gaap	Pension And Other Postretirement Benefit Expense PensionAndOtherPostretirementBenefitExpense	778000	USD
	us-gaap	Other Noncash Income Expense OtherNoncashIncomeExpense	-1103000	USD
	us-gaap	Increase Decrease In Other Current Assets IncreaseDecreaseInOtherCurrentAssets	-15259000	USD
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CY2017Q4	us-gaap	Regulatory Liability Current RegulatoryLiabilityCurrent	5633000	USD
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	us-gaap	Regulated Operating Revenue Electric Non Nuclear RegulatedOperatingRevenueElectricNonNuclear	313537000	USD
CY2018Q3	us-gaap	Unbilled Receivables Current UnbilledReceivablesCurrent	20979000	USD
CY2017Q4	us-gaap	Unbilled Receivables Current UnbilledReceivablesCurrent	31400000	USD
	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-659000	USD
	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	10991000	USD
CY2017Q4	us-gaap	Stockholders Equity StockholdersEquity	778187000	USD
CY2016Q4	us-gaap	Stockholders Equity StockholdersEquity	724088000	USD
CY2017Q4	us-gaap	Defined Benefit Plan Assets For Plan Benefits Noncurrent DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent	7336000	USD
CY2018Q3	us-gaap	Defined Benefit Plan Assets For Plan Benefits Noncurrent DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent	14266000	USD
	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	100000000	USD
CY2017Q4	us-gaap	Assets Held For Sale Not Part Of Disposal Group Current AssetsHeldForSaleNotPartOfDisposalGroupCurrent	8817000	USD
CY2018Q3	us-gaap	Assets Held For Sale Not Part Of Disposal Group Current AssetsHeldForSaleNotPartOfDisposalGroupCurrent	1755000	USD
CY2017Q3	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	2338000	USD
CY2017Q3	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	2070000	USD
CY2017Q3	us-gaap	Payments To Acquire Interest In Subsidiaries And Affiliates PaymentsToAcquireInterestInSubsidiariesAndAffiliates	710000	USD
CY2018Q3	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	1581000	USD
CY2018Q3	us-gaap	Payments To Acquire Interest In Subsidiaries And Affiliates PaymentsToAcquireInterestInSubsidiariesAndAffiliates	533000	USD
CY2018Q3	us-gaap	Short Term Borrowings ShortTermBorrowings	0	USD
CY2017Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	4000000	USD
	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	-4000000	USD
CY2017Q4	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis With Unobservable Inputs FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs	-42026000	USD
CY2017Q4	us-gaap	Notes And Loans Receivable Net Noncurrent NotesAndLoansReceivableNetNoncurrent	4788000	USD
CY2018Q3	us-gaap	Notes And Loans Receivable Net Noncurrent NotesAndLoansReceivableNetNoncurrent	3747000	USD
CY2017Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest Adjusted Balance1 StockholdersEquityIncludingPortionAttributableToNoncontrollingInterestAdjustedBalance1	778187000	USD
CY2017Q4	us-gaap	Derivative Liability Collateral Right To Reclaim Cash Offset DerivativeLiabilityCollateralRightToReclaimCashOffset	100000	USD
CY2018Q3	us-gaap	Derivative Liability Collateral Right To Reclaim Cash Offset DerivativeLiabilityCollateralRightToReclaimCashOffset	0	USD
CY2018Q3	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	133855000	USD
CY2017Q4	us-gaap	Cash And Cash Equivalents At Carrying Value CashAndCashEquivalentsAtCarryingValue	107952000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	22947000	USD
CY2017Q4	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	1635000	USD
	us-gaap	Dilutive Securities DilutiveSecurities	0	USD
CY2017Q4	us-gaap	Cumulative Effect Of New Accounting Principle In Period Of Adoption CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	0	USD
CY2016Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	101633000	USD
CY2017Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	108062000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	112094000	USD
CY2017Q4	us-gaap	Margin Deposit Assets MarginDepositAssets	2507000	USD
CY2018Q3	us-gaap	Utilities Operating Expense Fuel Used UtilitiesOperatingExpenseFuelUsed	16793000	USD
CY2018Q3	us-gaap	Utilities Operating Expense Purchased Power UtilitiesOperatingExpensePurchasedPower	13024000	USD
CY2018Q3	mgee	Utilities Operating Expense Cost Of Gas Sold UtilitiesOperatingExpenseCostOfGasSold	4921000	USD
CY2018Q3	us-gaap	Utilities Operating Expense Maintenance And Operations UtilitiesOperatingExpenseMaintenanceAndOperations	44130000	USD
CY2018Q3	us-gaap	Utilities Operating Expense Taxes UtilitiesOperatingExpenseTaxes	4870000	USD
CY2018Q3	us-gaap	Utilities Operating Expense UtilitiesOperatingExpense	97997000	USD
CY2018Q3	us-gaap	Net Income Loss NetIncomeLoss	29506000	USD
CY2018Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	39103000	USD
CY2018Q3	us-gaap	Regulated And Unregulated Operating Revenue RegulatedAndUnregulatedOperatingRevenue	137795000	USD
CY2018Q3	us-gaap	Utilities Operating Expense Depreciation And Amortization UtilitiesOperatingExpenseDepreciationAndAmortization	14259000	USD
CY2018Q3	us-gaap	Regulated Operating Revenue Electric Non Nuclear RegulatedOperatingRevenueElectricNonNuclear	119388000	USD
CY2018Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	9597000	USD
CY2017Q3	us-gaap	Regulated And Unregulated Operating Revenue RegulatedAndUnregulatedOperatingRevenue	139539000	USD
CY2017Q3	us-gaap	Utilities Operating Expense Fuel Used UtilitiesOperatingExpenseFuelUsed	15829000	USD
CY2017Q3	us-gaap	Utilities Operating Expense Purchased Power UtilitiesOperatingExpensePurchasedPower	15984000	USD
CY2017Q3	mgee	Utilities Operating Expense Cost Of Gas Sold UtilitiesOperatingExpenseCostOfGasSold	5094000	USD
CY2017Q3	us-gaap	Utilities Operating Expense Maintenance And Operations UtilitiesOperatingExpenseMaintenanceAndOperations	42533000	USD
CY2017Q3	us-gaap	Utilities Operating Expense Depreciation And Amortization UtilitiesOperatingExpenseDepreciationAndAmortization	13372000	USD
CY2017Q3	us-gaap	Utilities Operating Expense Taxes UtilitiesOperatingExpenseTaxes	4730000	USD
CY2017Q3	us-gaap	Operating Income Loss OperatingIncomeLoss	41997000	USD
CY2017Q3	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	4943000	USD
CY2017Q3	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-4727000	USD
CY2017Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	42213000	USD
CY2017Q3	us-gaap	Net Income Loss NetIncomeLoss	26629000	USD
CY2017Q3	us-gaap	Regulated Operating Revenue Electric Non Nuclear RegulatedOperatingRevenueElectricNonNuclear	120761000	USD
CY2017Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	15584000	USD
	us-gaap	Net Income Loss NetIncomeLoss	67858000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	89650000	USD
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-14547000	USD
	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	13980000	USD
	us-gaap	Operating Income Loss OperatingIncomeLoss	90217000	USD
	us-gaap	Regulated And Unregulated Operating Revenue RegulatedAndUnregulatedOperatingRevenue	419689000	USD
	us-gaap	Utilities Operating Expense Depreciation And Amortization UtilitiesOperatingExpenseDepreciationAndAmortization	41754000	USD
	us-gaap	Regulated And Unregulated Operating Revenue RegulatedAndUnregulatedOperatingRevenue	422825000	USD
	us-gaap	Utilities Operating Expense Depreciation And Amortization UtilitiesOperatingExpenseDepreciationAndAmortization	39606000	USD
	us-gaap	Operating Income Loss OperatingIncomeLoss	99428000	USD
	us-gaap	Nonoperating Income Expense NonoperatingIncomeExpense	12038000	USD
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	-14507000	USD
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Domestic IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic	96959000	USD
	us-gaap	Net Income Loss NetIncomeLoss	61472000	USD
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	35487000	USD
CY2018Q3	us-gaap	Earnings Per Share Basic And Diluted EarningsPerShareBasicAndDiluted	0.85
CY2017Q3	us-gaap	Earnings Per Share Basic And Diluted EarningsPerShareBasicAndDiluted	0.77
CY2018Q3	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.338
CY2017Q3	us-gaap	Common Stock Dividends Per Share Cash Paid CommonStockDividendsPerShareCashPaid	0.323
CY2017Q3	us-gaap	Weighted Average Number Of Share Outstanding Basic And Diluted WeightedAverageNumberOfShareOutstandingBasicAndDiluted	34668000	shares
CY2018Q3	us-gaap	Weighted Average Number Of Share Outstanding Basic And Diluted WeightedAverageNumberOfShareOutstandingBasicAndDiluted	34668000	shares
CY2018Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	0	USD
CY2018Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	29506000	USD
CY2017Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	60000	USD
CY2017Q3	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	26689000	USD
CY2018Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	0	USD
CY2017Q3	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	40000	USD
	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	6113000	USD
	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	5336000	USD
	us-gaap	Payments To Acquire Interest In Subsidiaries And Affiliates PaymentsToAcquireInterestInSubsidiariesAndAffiliates	4801000	USD
	us-gaap	Pension And Other Postretirement Benefit Contributions PensionAndOtherPostretirementBenefitContributions	9717000	USD
	us-gaap	Increase Decrease In Other Noncurrent Assets And Liabilities Net IncreaseDecreaseInOtherNoncurrentAssetsAndLiabilitiesNet	-2671000	USD
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	96146000	USD
	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	66286000	USD
	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-161000	USD
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-70589000	USD
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	32502000	USD
	us-gaap	Repayments Of Long Term Debt RepaymentsOfLongTermDebt	33260000	USD
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-19128000	USD
	us-gaap	Proceeds From Payments For Other Financing Activities ProceedsFromPaymentsForOtherFinancingActivities	-366000	USD
	us-gaap	Capital Expenditures Incurred But Not Yet Paid CapitalExpendituresIncurredButNotYetPaid	12469000	USD
	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	40000000	USD
	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	7432000	USD
	us-gaap	Equity Method Investment Dividends Or Distributions EquityMethodInvestmentDividendsOrDistributions	6142000	USD
	us-gaap	Payments To Acquire Interest In Subsidiaries And Affiliates PaymentsToAcquireInterestInSubsidiariesAndAffiliates	6863000	USD
	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	7000000	USD
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	6429000	USD
CY2018Q3	mgee	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Regulatory Liabilities Assets FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInRegulatoryLiabilitiesAssets	2018000	USD
CY2018Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Other Comprehensive Income Loss FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInOtherComprehensiveIncomeLoss	0	USD
CY2018Q3	mgee	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Current Assets FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInCurrentAssets	-25000	USD
CY2018Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Purchases FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases	5736000	USD
CY2018Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Sales FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSales	0	USD
CY2018Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Issues FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues	0	USD
CY2018Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Settlements FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements	5737000	USD
CY2018Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Transfers Net FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersNet	0	USD
CY2018Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Earnings FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings	26000	USD
CY2018Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis With Unobservable Inputs FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs	-35314000	USD
CY2018Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Change In Unrealized Gain Loss FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainLoss	0	USD
CY2017Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Earnings FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings	-1478000	USD
CY2017Q3	mgee	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Regulatory Liabilities Assets FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInRegulatoryLiabilitiesAssets	2846000	USD
CY2017Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Other Comprehensive Income Loss FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInOtherComprehensiveIncomeLoss	0	USD
CY2017Q3	mgee	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Current Assets FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInCurrentAssets	-14000	USD
CY2017Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Purchases FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases	6299000	USD
CY2017Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Sales FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSales	0	USD
CY2017Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Issues FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues	0	USD
CY2017Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Settlements FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements	4807000	USD
CY2017Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Transfers Net FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersNet	0	USD
CY2017Q2	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis With Unobservable Inputs FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs	-45605000	USD
CY2017Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Change In Unrealized Gain Loss FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisChangeInUnrealizedGainLoss	0	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Earnings FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings	-434000	USD
	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis Unobservable Inputs Reconciliation Gain Loss Included In Earnings FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings	-2614000	USD
CY2018Q3	mgee	Utilities Operating Expense Excluding Depreciation And Amortization UtilitiesOperatingExpenseExcludingDepreciationAndAmortization	83738000	USD
CY2017Q3	mgee	Utilities Operating Expense Excluding Depreciation And Amortization UtilitiesOperatingExpenseExcludingDepreciationAndAmortization	84170000	USD
CY2018Q3	us-gaap	Margin Deposit Assets MarginDepositAssets	780000	USD
	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	32502000	USD
CY2018Q3	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Including Disposal Group And Discontinued Operations CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations	135041000	USD
CY2018Q3	us-gaap	Restricted Cash And Cash Equivalents At Carrying Value RestrictedCashAndCashEquivalentsAtCarryingValue	406000	USD
CY2018Q3	us-gaap	Income Loss From Equity Method Investments IncomeLossFromEquityMethodInvestments	1672000	USD
CY2017Q3	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35	pure
CY2017Q3	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.052	pure
CY2017Q3	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Investment EffectiveIncomeTaxRateReconciliationTaxCreditsInvestment	0.003	pure
CY2017Q3	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Other EffectiveIncomeTaxRateReconciliationTaxCreditsOther	0.011	pure
CY2017Q3	us-gaap	Effective Income Tax Rate Reconciliation Deductions Qualified Production Activities EffectiveIncomeTaxRateReconciliationDeductionsQualifiedProductionActivities	0.015	pure
CY2017Q3	us-gaap	Effective Income Tax Rate Reconciliation Deductions Other EffectiveIncomeTaxRateReconciliationDeductionsOther	0.001	pure
CY2017Q3	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0	pure
CY2017Q3	us-gaap	Effective Income Tax Rate Reconciliation Other Reconciling Items Percent EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent	0.003	pure
CY2017Q3	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.369	pure
	us-gaap	Increase Decrease In Other Current Assets IncreaseDecreaseInOtherCurrentAssets	-25530000	USD
CY2018Q3	us-gaap	Stockholders Equity StockholdersEquity	811983000	USD
	mgee	Jointlyownedutilityplantintereststextblock Jointlyownedutilityplantintereststextblock	<div><p style='text-align:left;margin-top:0pt;margin-bottom:0pt;line-height:12pt;' ><font style='font-family:Times New Roman;font-size:10pt;font-weight:bold;margin-left:0pt;' >Joint Plant Ownership</font><font style='font-family:Times New Roman;font-size:10pt;font-weight:bold;' > - MGE Energy and MGE.</font></p><p style='text-align:left;line-height:12pt;' ></p><p style='text-align:left;margin-top:0pt;margin-bottom:0pt;line-height:12pt;' ><font style='font-family:Times New Roman;font-size:10pt;font-weight:bold;margin-left:45pt;' >a.</font><font style='font-family:Times New Roman;font-size:10pt;font-weight:bold;' > </font><font style='font-family:Times New Roman;font-size:10pt;font-weight:bold;' >Columbia.</font></p><p style='text-align:left;line-height:12pt;' ></p><p style='text-align:left;margin-top:0pt;margin-bottom:0pt;line-height:12pt;' ><font style='font-family:Times New Roman;font-size:10pt;margin-left:45.35pt;' >In 2016, MGE and WPL negotiated an amendment to the existing Columbia joint operating agreement tha</font><font style='font-family:Times New Roman;font-size:10pt;' >t has been approved by the PSCW. Under the terms of the amendments,</font><font style='font-family:Times New Roman;font-size:10pt;' > MGE </font><font style='font-family:Times New Roman;font-size:10pt;' >has</font><font style='font-family:Times New Roman;font-size:10pt;' > reduce</font><font style='font-family:Times New Roman;font-size:10pt;' >d</font><font style='font-family:Times New Roman;font-size:10pt;' > its obligation to pay certain capital expenditures (other than SCR-related expenditures) at Columbia in exchange for a proportional reduction in MGE's ownership in Columbia. On January 1 of each year</font><font style='font-family:Times New Roman;font-size:10pt;' > from 2017 through 20</font><font style='font-family:Times New Roman;font-size:10pt;' >19 and then on </font><font style='font-family:Times New Roman;font-size:10pt;' >June 1, 2020, the ownership percentage </font><font style='font-family:Times New Roman;font-size:10pt;' >is</font><font style='font-family:Times New Roman;font-size:10pt;' > adjusted</font><font style='font-family:Times New Roman;font-size:10pt;' > through a partial sale</font><font style='font-family:Times New Roman;font-size:10pt;' > based on the amount of capital expenditures foregone. In </font><font style='font-family:Times New Roman;font-size:10pt;' >June 2017, the FERC approved the ownership transfer in Columbia</font><font style='font-family:Times New Roman;font-size:10pt;' >, effective January 1, 2017. </font></p><p style='text-align:left;line-height:12pt;' ></p><p style='text-align:left;margin-top:0pt;margin-bottom:0pt;line-height:12pt;' ><font style='font-family:Times New Roman;font-size:10pt;margin-left:45.35pt;' >During 201</font><font style='font-family:Times New Roman;font-size:10pt;' >7</font><font style='font-family:Times New Roman;font-size:10pt;' >, MGE</font><font style='font-family:Times New Roman;font-size:10pt;' > accrued $</font><font style='font-family:Times New Roman;font-size:10pt;' >8.8</font><font style='font-family:Times New Roman;font-size:10pt;' > million of 201</font><font style='font-family:Times New Roman;font-size:10pt;' >7</font><font style='font-family:Times New Roman;font-size:10pt;' > </font><font style='font-family:Times New Roman;font-size:10pt;' >foregone </font><font style='font-family:Times New Roman;font-size:10pt;' >capital expenditures as part of the ownership transfer agreement </font><font style='font-family:Times New Roman;font-size:10pt;' >with WPL. As of December 31, 2017</font><font style='font-family:Times New Roman;font-size:10pt;' >, MGE classified $</font><font style='font-family:Times New Roman;font-size:10pt;' >8.8</font><font style='font-family:Times New Roman;font-size:10pt;' > million of Columbia assets as held-for-sale on the </font><font style='font-family:Times New Roman;font-size:10pt;' >consolidated balance sheets. In January 201</font><font style='font-family:Times New Roman;font-size:10pt;' >8</font><font style='font-family:Times New Roman;font-size:10pt;' >, MGE reduced its ownership interest in Columbia from </font><font style='font-family:Times New Roman;font-size:10pt;' >20.4</font><font style='font-family:Times New Roman;font-size:10pt;' >% to </font><font style='font-family:Times New Roman;font-size:10pt;' >19.4</font><font style='font-family:Times New Roman;font-size:10pt;' >% </font><font style='font-family:Times New Roman;font-size:10pt;' >as a result of</font><font style='font-family:Times New Roman;font-size:10pt;' > the partial sale of plant assets to WPL.</font></p><p style='text-align:left;line-height:12pt;' ></p><p style='text-align:left;margin-top:0pt;margin-bottom:0pt;line-height:12pt;' ><font style='font-family:Times New Roman;font-size:10pt;margin-left:45.35pt;' >During </font><font style='font-family:Times New Roman;font-size:10pt;' >the </font><font style='font-family:Times New Roman;font-size:10pt;' >three and nine months ended</font><font style='font-family:Times New Roman;font-size:10pt;' > </font><font style='font-family:Times New Roman;font-size:10pt;' >September 30,</font><font style='font-family:Times New Roman;font-size:10pt;' > </font><font style='font-family:Times New Roman;font-size:10pt;' >2018</font><font style='font-family:Times New Roman;font-size:10pt;' >, MGE accrued </font><font style='font-family:Times New Roman;font-size:10pt;' >$</font><font style='font-family:Times New Roman;font-size:10pt;' >0.4</font><font style='font-family:Times New Roman;font-size:10pt;' > </font><font style='font-family:Times New Roman;font-size:10pt;' >million</font><font style='font-family:Times New Roman;font-size:10pt;' > and </font><font style='font-family:Times New Roman;font-size:10pt;' >$</font><font style='font-family:Times New Roman;font-size:10pt;' >1.8</font><font style='font-family:Times New Roman;font-size:10pt;' > million, respectively,</font><font style='font-family:Times New Roman;font-size:10pt;' > of 201</font><font style='font-family:Times New Roman;font-size:10pt;' >8</font><font style='font-family:Times New Roman;font-size:10pt;' > </font><font style='font-family:Times New Roman;font-size:10pt;' >foregone </font><font style='font-family:Times New Roman;font-size:10pt;' >capital expenditures </font><font style='font-family:Times New Roman;font-size:10pt;' >as part of</font><font style='font-family:Times New Roman;font-size:10pt;' > t</font><font style='font-family:Times New Roman;font-size:10pt;' >he ownership transfer agreement</font><font style='font-family:Times New Roman;font-size:10pt;' >. As of </font><font style='font-family:Times New Roman;font-size:10pt;' >September 30,</font><font style='font-family:Times New Roman;font-size:10pt;' > </font><font style='font-family:Times New Roman;font-size:10pt;' >2018</font><font style='font-family:Times New Roman;font-size:10pt;' >, MGE classified </font><font style='font-family:Times New Roman;font-size:10pt;' >$</font><font style='font-family:Times New Roman;font-size:10pt;' >1.8</font><font style='font-family:Times New Roman;font-size:10pt;' > million of Columbia assets as held-for-sale on the consolidated balance sheets.</font><font style='font-family:Times New Roman;font-size:10pt;' > The assets recognized as held-for-sale are covered by </font><font style='font-family:Times New Roman;font-size:10pt;' >the ownership transfer agreement relating to</font><font style='font-family:Times New Roman;font-size:10pt;' > the sale of plant assets to WPL, and are</font><font style='font-family:Times New Roman;font-size:10pt;' > expected to be sold and transferred</font><font style='font-family:Times New Roman;font-size:10pt;' > in Ja</font><font style='font-family:Times New Roman;font-size:10pt;' >nuary 2019.</font></p></div><p style='line-height:20pt;' /><div><p style='text-align:left;margin-top:0pt;margin-bottom:0pt;line-height:12pt;' ><font style='font-family:Times New Roman;font-size:10pt;font-weight:bold;margin-left:45pt;' >b. Forward Wind.</font></p><p style='text-align:left;line-height:12pt;' ></p><p style='text-align:left;margin-top:0pt;margin-bottom:0pt;line-height:12pt;' ><font style='font-family:Times New Roman;font-size:10pt;margin-left:45.35pt;' >In April 2018, MGE, along with two other utilities, purchased the Forward Wind Energy Center</font><font style='font-family:Times New Roman;font-size:10pt;' > (Forward Wind)</font><font style='font-family:Times New Roman;font-size:10pt;' >, which consists of 86 wind turbines located in Wisconsin with a total capacity of 129 MWs. The aggregate purchase price was </font><font style='font-family:Times New Roman;font-size:10pt;' >approximately $174 million</font><font style='font-family:Times New Roman;font-size:10pt;' >,</font><font style='font-family:Times New Roman;font-size:10pt;' > of which MGE's proportionate share is 12.8%, or approximately $23 million. The purchase of Forward Wind replaced an existing purchase power agreement, </font><font style='font-family:Times New Roman;font-size:10pt;' >under </font><font style='font-family:Times New Roman;font-size:10pt;' >which MGE purchased 12.8% of the facility's energy output.</font></p><p style='text-align:left;line-height:12pt;' ></p><p style='text-align:left;margin-top:0pt;margin-bottom:0pt;line-height:12pt;' ><font style='font-family:Times New Roman;font-size:10pt;margin-left:45.35pt;' >MGE Energy a</font><font style='font-family:Times New Roman;font-size:10pt;' >nd MGE are required to record a liability for the fair value of an </font><font style='font-family:Times New Roman;font-size:10pt;' >asset retirement obligation (</font><font style='font-family:Times New Roman;font-size:10pt;' >ARO</font><font style='font-family:Times New Roman;font-size:10pt;' >)</font><font style='font-family:Times New Roman;font-size:10pt;' > to be recognized in the period in which it is incurred if it can be reasonably estimated. The offsetting associated asset retirement costs are capitalized </font><font style='font-family:Times New Roman;font-size:10pt;' >as a long-lived asset and depreciated over the asset's useful life. As of </font><font style='font-family:Times New Roman;font-size:10pt;color:#000000;' >September 30,</font><font style='font-family:Times New Roman;font-size:10pt;color:#000000;' > </font><font style='font-family:Times New Roman;font-size:10pt;color:#000000;' >2018</font><font style='font-family:Times New Roman;font-size:10pt;' >, MGE recorded an obligation of $</font><font style='font-family:Times New Roman;font-size:10pt;' >1.6</font><font style='font-family:Times New Roman;font-size:10pt;' > million for the fair value of its legal liability for AROs associated with </font><font style='font-family:Times New Roman;font-size:10pt;' >Forward Wind</font><font style='font-family:Times New Roman;font-size:10pt;' >. MGE has regulatory treatment and recogn</font><font style='font-family:Times New Roman;font-size:10pt;' >izes regulatory assets or liabilities for the timing differences between when we recover legal AROs in rates and when those costs would actually be recognized.</font></p></div>
CY2018Q3	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21	pure
CY2018Q3	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.063	pure
CY2018Q3	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Investment EffectiveIncomeTaxRateReconciliationTaxCreditsInvestment	0.001	pure
CY2018Q3	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Other EffectiveIncomeTaxRateReconciliationTaxCreditsOther	0.003	pure
CY2018Q3	us-gaap	Effective Income Tax Rate Reconciliation Deductions Qualified Production Activities EffectiveIncomeTaxRateReconciliationDeductionsQualifiedProductionActivities	0	pure
CY2018Q3	us-gaap	Effective Income Tax Rate Reconciliation Deductions Other EffectiveIncomeTaxRateReconciliationDeductionsOther	0.006	pure
CY2018Q3	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0.018	pure
CY2018Q3	us-gaap	Effective Income Tax Rate Reconciliation Other Reconciling Items Percent EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent	0	pure
	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.35	pure
	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.052	pure
	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.063	pure
	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Investment EffectiveIncomeTaxRateReconciliationTaxCreditsInvestment	0.003	pure
	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Other EffectiveIncomeTaxRateReconciliationTaxCreditsOther	0.013	pure
	us-gaap	Effective Income Tax Rate Reconciliation Deductions Qualified Production Activities EffectiveIncomeTaxRateReconciliationDeductionsQualifiedProductionActivities	0.016	pure
	us-gaap	Effective Income Tax Rate Reconciliation Deductions Other EffectiveIncomeTaxRateReconciliationDeductionsOther	0.002	pure
	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0	pure
	us-gaap	Effective Income Tax Rate Reconciliation Other Reconciling Items Percent EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent	0.002	pure
	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.366	pure
	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Investment EffectiveIncomeTaxRateReconciliationTaxCreditsInvestment	0.001	pure
	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits Other EffectiveIncomeTaxRateReconciliationTaxCreditsOther	0.003	pure
	us-gaap	Effective Income Tax Rate Reconciliation Deductions Qualified Production Activities EffectiveIncomeTaxRateReconciliationDeductionsQualifiedProductionActivities	0	pure
	us-gaap	Effective Income Tax Rate Reconciliation Deductions Other EffectiveIncomeTaxRateReconciliationDeductionsOther	0.008	pure
	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0.018	pure
	us-gaap	Effective Income Tax Rate Reconciliation Other Reconciling Items Percent EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent	0	pure
	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.243	pure
CY2018Q3	us-gaap	Purchase Obligation Future Minimum Payments Remainder Of Fiscal Year PurchaseObligationFutureMinimumPaymentsRemainderOfFiscalYear	21739000	USD
CY2018Q3	us-gaap	Purchase Obligation Due In Second Year PurchaseObligationDueInSecondYear	35835000	USD
CY2018Q3	us-gaap	Purchase Obligation Due In Third Year PurchaseObligationDueInThirdYear	11202000	USD
CY2018Q3	us-gaap	Purchase Obligation Due In Fourth Year PurchaseObligationDueInFourthYear	3105000	USD
CY2018Q3	us-gaap	Purchase Obligation Due In Fifth Year PurchaseObligationDueInFifthYear	2286000	USD
CY2018Q3	us-gaap	Purchase Obligation Due After Fifth Year PurchaseObligationDueAfterFifthYear	4961000	USD
CY2017	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	108131000	USD
CY2017Q3	us-gaap	Stockholders Equity StockholdersEquity	753247000	USD
CY2017Q4	mgee	Forward Wind Purchase Power Energy Output ForwardWindPurchasePowerEnergyOutput	0.128	pure
CY2018Q1	mgee	Forward Wind Purchase Power Energy Output ForwardWindPurchasePowerEnergyOutput	0.128	pure
	us-gaap	Gain Loss On Disposition Of Assets GainLossOnDispositionOfAssets	1581000	USD
	us-gaap	Gain Loss On Disposition Of Assets GainLossOnDispositionOfAssets	0	USD
	us-gaap	Proceeds From Sale Of Other Property Plant And Equipment ProceedsFromSaleOfOtherPropertyPlantAndEquipment	0	USD
	us-gaap	Proceeds From Sale Of Other Property Plant And Equipment ProceedsFromSaleOfOtherPropertyPlantAndEquipment	2399000	USD
CY2018Q3	us-gaap	Regulated Operating Revenue Gas RegulatedOperatingRevenueGas	18407000	USD
CY2017Q3	us-gaap	Regulated Operating Revenue Gas RegulatedOperatingRevenueGas	18778000	USD
	us-gaap	Regulated Operating Revenue Gas RegulatedOperatingRevenueGas	106152000	USD
	us-gaap	Regulated Operating Revenue Gas RegulatedOperatingRevenueGas	101285000	USD
CY2018Q2	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis With Unobservable Inputs FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs	-37332000	USD
CY2017Q3	us-gaap	Fair Value Net Derivative Asset Liability Measured On Recurring Basis With Unobservable Inputs FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs	-42759000	USD
	dei	Entity Central Index Key EntityCentralIndexKey	0001161728
	dei	Document Type DocumentType	10-Q
	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q3
	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2017Q3	mgee	Capitalized Computer Software Hosting Agreement Amortization CapitalizedComputerSoftwareHostingAgreementAmortization	0	USD
	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
	dei	Entity Small Business EntitySmallBusiness	false
CY2018Q3	mgee	Capitalized Computer Software Hosting Agreement Net CapitalizedComputerSoftwareHostingAgreementNet	6200000	USD
CY2017Q4	mgee	Capitalized Computer Software Hosting Agreement Net CapitalizedComputerSoftwareHostingAgreementNet	500000	USD
CY2018Q3	mgee	Capitalized Computer Software Hosting Agreement Accumulated Amortization CapitalizedComputerSoftwareHostingAgreementAccumulatedAmortization	100000	USD
CY2017Q4	mgee	Capitalized Computer Software Hosting Agreement Accumulated Amortization CapitalizedComputerSoftwareHostingAgreementAccumulatedAmortization	0	USD
CY2018Q3	mgee	Capitalized Computer Software Hosting Agreement Amortization CapitalizedComputerSoftwareHostingAgreementAmortization	100000	USD
	mgee	Capitalized Computer Software Hosting Agreement Amortization CapitalizedComputerSoftwareHostingAgreementAmortization	100000	USD
	mgee	Capitalized Computer Software Hosting Agreement Amortization CapitalizedComputerSoftwareHostingAgreementAmortization	0	USD
CY2018Q3	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.245	pure

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2018 Q4 Form 10-Q Financial Statement

#000116172818000035 Filed on November 06, 2018

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$MGEE MGE ENERGY INC Stock $mgee

2018 Q4 Form 10-Q Financial Statement

#000116172818000035 Filed on November 06, 2018

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$MGEE
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