MGE Energy (MGEE) 10-Q 8 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 30, 2019
Document And Entity Information [Line Items]
Entity Registrant Name	MGE Energy Inc
Entity Central Index Key	0001161728
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Trading Symbol	MGEE
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock Shares Outstanding		34,668,370
Entity Emerging Growth Company	false
Entity Small Business	false
MGE [Member]
Document And Entity Information [Line Items]
Entity Registrant Name	Madison Gas and Electric Company
Entity Central Index Key	0000061339
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock Shares Outstanding		17,347,894

MGE Energy Inc Consolidated Sta

MGE Energy Inc Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating Revenues:
Electric revenues	$ 97,469	$ 94,867
Gas revenue	70,100	62,765
Total Operating Revenues	167,569	157,632
Operating Expenses:
Fuel for electric generation	13,917	11,900
Purchased power	10,851	17,033
Cost of gas sold	43,253	39,626
Other operations and maintenance	46,934	44,393
Depreciation and amortization	17,139	13,623
Other general taxes	4,963	4,869
Total Operating Expenses	137,057	131,444
Operating Income	30,512	26,188
Other income, net	4,851	4,919
Interest expense, net	(5,647)	(4,739)
Income before income taxes	29,716	26,368
Income tax provision	(5,709)	(6,367)
Net Income	$ 24,007	$ 20,001
Earnings Per Share of Common Stock (basic and diluted)	$ 0.69	$ 0.58
Dividends per share of common stock	$ 0.338	$ 0.323
Weighted Average Shares Outstanding (basic and diluted)	34,668	34,668

Madison Gas and Electric Compan

Madison Gas and Electric Company Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating Revenues:
Electric revenues	$ 97,469	$ 94,867
Gas revenue	70,100	62,765
Total Operating Revenues	167,569	157,632
Operating Expenses:
Fuel for electric generation	13,917	11,900
Purchased power	10,851	17,033
Cost of gas sold	43,253	39,626
Other operations and maintenance	46,934	44,393
Depreciation and amortization	17,139	13,623
Other general taxes	4,963	4,869
Total Operating Expenses	137,057	131,444
Operating Income	30,512	26,188
Other income, net	4,851	4,919
Interest expense, net	(5,647)	(4,739)
Income before income taxes	29,716	26,368
Income tax provision	(5,709)	(6,367)
Net Income	24,007	20,001
MGE [Member]
Operating Revenues:
Electric revenues	97,469	94,867
Gas revenue	70,100	62,765
Total Operating Revenues	167,569	157,632
Operating Expenses:
Fuel for electric generation	13,917	11,900
Purchased power	10,851	17,033
Cost of gas sold	43,253	39,626
Other operations and maintenance	46,662	44,187
Depreciation and amortization	17,139	13,623
Other general taxes	4,963	4,869
Total Operating Expenses	136,785	131,238
Operating Income	30,784	26,394
Other income, net	2,207	2,497
Interest expense, net	(5,995)	(5,054)
Income before income taxes	26,996	23,837
Income tax provision	(4,926)	(5,581)
Net Income Including Noncontrolling Interest	22,070	18,256
Less Net Income Attributable to Noncontrolling Interest, net of tax	(5,490)	(5,806)
Net Income	$ 16,580	$ 12,450

MGE Energy Inc Consolidated S_2

MGE Energy Inc Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating Activities:
Net Income	$ 24,007	$ 20,001
Items not affecting cash:
Depreciation and amortization	17,139	13,623
Deferred income taxes	(1,359)	(1,793)
Provision for doubtful receivables	634	264
Employee benefit plan cost (credit)	474	(561)
Equity earnings in ATC	(2,218)	(2,451)
Other items	32	(152)
Changes in working capital items:
Decrease in current assets	13,665	25,208
Increase (decrease) in current liabilities	3,182	(7,771)
Dividends from ATC	2,012	2,348
Cash contributions to pension and other postretirement plans	(957)	(1,319)
Other noncurrent items, net	(3,416)	(419)
Cash Provided by Operating Activities	53,195	46,978
Investing Activities:
Capital expenditures	(31,933)	(37,631)
Capital contributions to investments	(740)	(1,877)
Other	(206)	(35)
Cash Used for Investing Activities	(32,879)	(39,543)
Financing Activities:
Cash dividends paid on common stock	(11,701)	(11,181)
Repayment of long-term debt	(1,129)	(1,103)
Repayments of short-term debt	(7,000)	(1,000)
Other	(999)	0
Cash Used for Financing Activities	(20,829)	(13,284)
Change in cash, cash equivalents, and restricted cash	(513)	(5,849)
Cash, cash equivalents, and restricted cash at beginning of period	84,929	112,094
Cash, cash equivalents, and restricted cash at end of period	84,416	106,245
Significant noncash investing activities:
Accrued capital expenditures	$ 3,428	$ 4,706

Madison Gas and Electric Comp_2

Madison Gas and Electric Company Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Items not affecting cash:
Depreciation and amortization	$ 17,139	$ 13,623
Deferred income taxes	(1,359)	(1,793)
Provision for doubtful receivables	634	264
Employee benefit plan cost (credit)	474	(561)
Equity earnings in MGE Transco	(2,218)	(2,451)
Other items	32	(152)
Changes in working capital items:
Decrease in current assets	13,665	25,208
Increase (decrease) in current liabilities	3,182	(7,771)
Cash contributions to pension and other postretirement plans	(957)	(1,319)
Other noncurrent items, net	(3,416)	(419)
Cash Provided by Operating Activities	53,195	46,978
Investing Activities:
Capital expenditures	(31,933)	(37,631)
Capital contributions to investments	(740)	(1,877)
Other	(206)	(35)
Cash Used for Investing Activities	(32,879)	(39,543)
Financing Activities:
Repayment of long-term debt	(1,129)	(1,103)
(Repayments of) proceeds from short-term debt	(7,000)	(1,000)
Other	(999)	0
Cash Used for Financing Activities	(20,829)	(13,284)
Change in cash, cash equivalents, and restricted cash	(513)	(5,849)
Cash, cash equivalents, and restricted cash at beginning of period	84,929	112,094
Cash, cash equivalents, and restricted cash at end of period	84,416	106,245
Significant noncash investing activities:
Accrued capital expenditures	3,428	4,706
MGE [Member]
Operating Activities:
Net Income	22,070	18,256
Items not affecting cash:
Depreciation and amortization	17,139	13,623
Deferred income taxes	(2,002)	(2,229)
Provision for doubtful receivables	634	264
Employee benefit plan cost (credit)	474	(561)
Other items	604	(17)
Changes in working capital items:
Decrease in current assets	13,737	24,779
Increase (decrease) in current liabilities	5,532	(5,749)
Cash contributions to pension and other postretirement plans	(957)	(1,319)
Other noncurrent items, net	(3,629)	(468)
Cash Provided by Operating Activities	53,602	46,579
Investing Activities:
Capital expenditures	(31,933)	(37,631)
Other	(228)	(198)
Cash Used for Investing Activities	(32,161)	(37,829)
Financing Activities:
Distributions to parent from noncontrolling interest	(7,500)	(7,500)
Repayment of long-term debt	(1,129)	(1,103)
(Repayments of) proceeds from short-term debt	(7,000)	(1,000)
Other	(844)	0
Cash Used for Financing Activities	(16,473)	(9,603)
Change in cash, cash equivalents, and restricted cash	4,968	(853)
Cash, cash equivalents, and restricted cash at beginning of period	6,670	10,093
Cash, cash equivalents, and restricted cash at end of period	11,638	9,240
Significant noncash investing activities:
Accrued capital expenditures	$ 3,428	$ 4,706

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 82,402	$ 83,102
Accounts receivable, less reserves	47,682	43,593
Other accounts receivables, less reserves	5,803	6,262
Unbilled revenues	23,849	28,243
Materials and supplies, at average cost	25,525	24,093
Fuel for electric generation, at average cost	4,466	6,599
Stored natural gas, at average cost	2,287	11,303
Prepaid taxes	12,436	16,215
Regulatory assets - current	9,301	9,477
Assets held for sale	0	3,080
Other current assets	7,527	8,593
Total Current Assets	221,278	240,560
Other long-term receivables	2,650	2,709
Regulatory assets	145,202	145,424
Other deferred assets and other	16,272	12,488
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,497,157	1,367,585
Finance lease assets, net, Finance lease assets	16,976	2,181
Construction work in progress	24,649	139,671
Total Property, Plant, and Equipment	1,538,782	1,509,437
Investments	79,382	78,000
Total Assets	2,003,566	1,988,618
Current Liabilities:
Long-term debt due within one year	4,579	4,553
Short-term debt	6,000	13,000
Accounts payable	40,356	46,158
Accrued interest and taxes	12,189	7,384
Accrued payroll related items	9,628	13,044
Regulatory liabilities - current	21,738	13,826
Derivative liabilities	8,730	8,550
Other current liabilities	9,257	14,113
Total Current Liabilities	112,477	120,628
Other Credits:
Deferred income taxes	231,557	231,952
Investment tax credit - deferred	795	818
Regulatory liabilities	163,161	165,638
Accrued pension and other postretirement benefits	66,116	67,483
Derivative liabilities	22,880	23,980
Finance lease liabilities	17,666	1,771
Other deferred liabilities and other	67,681	66,361
Total Other Credits	569,856	558,003
Capitalization:
Common shareholders equity	828,950	816,644	$ 778,187
Long-term debt	492,283	493,343
Total Capitalization	1,321,233	1,309,987
Commitments and contingencies (see Footnote 9)
Total Liabilities and Capitalization	2,003,566	1,988,618
MGE [Member]
Current Assets:
Cash and cash equivalents	9,624	4,843
Accounts receivable, less reserves	47,682	43,593
Affiliate receivables	207	621
Other accounts receivables, less reserves	5,725	6,111
Unbilled revenues	23,849	28,243
Materials and supplies, at average cost	25,525	24,093
Fuel for electric generation, at average cost	4,466	6,599
Stored natural gas, at average cost	2,287	11,303
Prepaid taxes	12,325	15,790
Regulatory assets - current	9,301	9,477
Assets held for sale	0	3,080
Other current assets	7,486	8,541
Total Current Assets	148,477	162,294
Affiliate receivable long-term	3,177	3,177
Regulatory assets	145,202	145,424
Other deferred assets and other	17,715	14,142
Property, Plant, and Equipment:
Property, plant, and equipment, net	1,497,186	1,367,614
Finance lease assets, net, Finance lease assets	16,976	2,181
Construction work in progress	24,649	139,671
Total Property, Plant, and Equipment	1,538,811	1,509,466
Investments	415	388
Total Assets	1,853,797	1,834,891
Current Liabilities:
Long-term debt due within one year	4,579	4,553
Short-term debt	6,000	13,000
Accounts payable	40,372	46,165
Accrued interest and taxes	15,169	10,319
Accrued payroll related items	9,628	13,044
Regulatory liabilities - current	21,738	13,826
Derivative liabilities	8,730	8,550
Other current liabilities	9,054	11,614
Total Current Liabilities	115,270	121,071
Other Credits:
Deferred income taxes	203,578	204,616
Investment tax credit - deferred	795	818
Regulatory liabilities	163,161	165,638
Accrued pension and other postretirement benefits	66,116	67,483
Derivative liabilities	22,880	23,980
Finance lease liabilities	17,666	1,771
Other deferred liabilities and other	67,668	66,361
Total Other Credits	541,864	530,667
Capitalization:
Common shareholders equity	564,936	548,356
Noncontrolling interest	139,444	141,454
Total Equity	704,380	689,810	632,774
Long-term debt	492,283	493,343
Total Capitalization	1,196,663	1,183,153
Commitments and contingencies (see Footnote 9)
Total Liabilities and Capitalization	$ 1,853,797	$ 1,834,891

Consolidated Balance Sheets (_2

Consolidated Balance Sheets (Unaudited) (Parentheticals) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Receivables, Net
Reserve for uncollectible accounts receivable	$ 2,842	$ 2,614
Reserve for uncollectible other accounts receivable	532	540
MGE [Member]
Receivables, Net
Reserve for uncollectible accounts receivable	2,842	2,614
Reserve for uncollectible other accounts receivable	$ 532	$ 540

MGE Energy Inc Consolidated S_3

MGE Energy Inc Consolidated Statements of Common Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]
Increase (Decrease) In Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting principle	$ 0			$ 377	$ (377)
Beginning balance, shares at Dec. 31, 2017		34,668
Beginning balance, value at Dec. 31, 2017	778,187	$ 34,668	$ 316,268	426,874	377
Beginning balance, value - Adjusted at Dec. 31, 2017	778,187			427,251	0
Increase (Decrease) In Stockholders' Equity [Roll Forward]
Net Income	20,001			20,001
Common stock dividends declared	(11,181)			(11,181)
Ending balance, shares at Mar. 31, 2018		34,668
Ending balance, value at Mar. 31, 2018	787,007	$ 34,668	316,268	436,071	0
Beginning balance, shares at Dec. 31, 2018		34,668
Beginning balance, value at Dec. 31, 2018	816,644	$ 34,668	316,268	465,708	0
Increase (Decrease) In Stockholders' Equity [Roll Forward]
Net Income	24,007			24,007
Common stock dividends declared	(11,701)			(11,701)
Ending balance, shares at Mar. 31, 2019		34,668
Ending balance, value at Mar. 31, 2019	$ 828,950	$ 34,668	$ 316,268	$ 478,014	$ 0

Madison Gas and Electric Comp_3

Madison Gas and Electric Company Consolidated Statements of Common Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	MGE [Member]	Common Stock [Member]	Common Stock [Member]MGE [Member]	Additional Paid-In Capital [Member]MGE [Member]	Retained Earnings [Member]	Retained Earnings [Member]MGE [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]MGE [Member]	Noncontrolling Interest [Member]MGE [Member]
Increase (Decrease) In Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting principle	$ 0	$ 0				$ 377	$ (28)	$ (377)	$ 28
Beginning balance, shares at Dec. 31, 2017			34,668	17,348
Beginning balance, value at Dec. 31, 2017		632,774		$ 17,348	$ 192,417		282,135		(28)	$ 140,902
Beginning balance, value - Adjusted at Dec. 31, 2017	$ 778,187	632,774				$ 427,251	282,107	$ 0	0
Increase (Decrease) In Stockholders' Equity [Roll Forward]
Net Income		18,256					12,450			5,806
Distributions to parent from noncontrolling interest		(7,500)								(7,500)
Ending balance, shares at Mar. 31, 2018			34,668	17,348
Ending balance, value at Mar. 31, 2018		643,530		$ 17,348	192,417		294,557		0	139,208
Beginning balance, shares at Dec. 31, 2018			34,668	17,348
Beginning balance, value at Dec. 31, 2018		689,810		$ 17,348	192,417		338,591		0	141,454
Increase (Decrease) In Stockholders' Equity [Roll Forward]
Net Income		22,070					16,580			5,490
Distributions to parent from noncontrolling interest		(7,500)								(7,500)
Ending balance, shares at Mar. 31, 2019			34,668	17,348
Ending balance, value at Mar. 31, 2019		$ 704,380		$ 17,348	$ 192,417		$ 355,171		$ 0	$ 139,444

Consolidated Statements of Comm

Consolidated Statements of Common Equity (Unaudited) (Parentheticals) - $ / shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Consolidated Statements of Common Equity
Dividends per share of common stock	$ 0.338	$ 0.323

Summary of Significant Accounti

Summary of Significant Accounting Principles	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Summary of Significant Accounting Policies. a. Basis of Presentation - MGE Energy and MGE. This report is a combined report of MGE Energy and MGE. References in this report to "MGE Energy " are to MGE Energy, Inc. and its subsidiaries. References in this report to "MGE" are to Madison Gas and Electric Company. MGE Power Elm Road and MGE Power West Campus own electric generating assets and lease those assets to MGE. Both entities are variable interest entities under applicable authoritative accounting guidance. MGE is considered the primary beneficiary of these entities as a result of contractual agreement s. As a result, MGE has consolidated MGE Power Elm Road and MGE Power West Campus . See Footnote 3 of Notes to Consolidated Financial Statements under Item 8, Financial Statements and Supplementary Data, of MGE Energy ' s and MGE ' s 2018 Annual Report on Fo rm 10-K (the 2018 Annual Report on Form 10-K). The accompanying consolidated financial statements as of March 31, 2019 , and for the three months ended , are unaudited but include all adjustments that MGE Energy and MGE management consider necessary for a fair statement of their respective financial statements. All adjustments are of a normal, recurring nature except as otherwise disclosed. The year-end consolidated bal ance sheet information was derived from the audited balance sheet appearing in the 2018 Annual Report on Form 10-K, but does not include all disclosures required by accounting principles generally accepted in the United States of America. These notes sh ould be read in conjunction with the financial statements and the notes on pages 62 through 1 06 of the 2018 Annual Report on Form 10-K . b. Cash, Cash Equivalents, and Restricted Cash - MGE Energy and MGE. The following table presents the components of total cash, cash equivalents and restricted cash on the consolidated balance sheets. MGE Energy MGE March 31, December 31, March 31, December 31, (In thousands) 2019 2018 2019 2018 Cash and cash equivalents $ 82,402 $ 83,102 $ 9,624 $ 4,843 Restricted cash 444 634 444 634 Receivable - margin account 1,570 1,193 1,570 1,193 Cash, cash equivalents, and restricted cash $ 84,416 $ 84,929 $ 11,638 $ 6,670 Cash Equivalents MGE Energy and MGE consider all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. Restricted Cash MGE has certain cash accounts that are restricted to uses other than current operations and designated for a specific purpose. MGE's restricted cash accounts include cash held by trustees for certain employee benefits and cash deposits held by third parties. These are included in "Other current assets" on the consolidated balance s heets. Receivable – Margin Account Cash balances held by counterparties as margin collateral for certain financial transactions are recorded as receivable – margin account in "Other current assets" on the consolidated balance sheets. The costs being hedged are fuel for electric generation, purchased power, and cost of gas sold.

Adoption of Accounting Principl

Adoption of Accounting Principles and Recently Issued Accounting Pronouncements	3 Months Ended
	Mar. 31, 2019
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	New Accounting Standards - MGE Energy and MGE. Recently Adopted Leases. In February 2016, the FASB issued authoritative guidance within the c odification's Leases topic that provides guidance on the classification, recognition, measurement, and disclosure of leases. The new leasing standard establishes that a lease conveys the right to control the use of identified property, plant, or equipment for a period of time in exchange for consideration. Under the new guidance, lessees are required to rec ognize all leases with terms greater than one year, including operating leases, on the balance sheet by recording a right-of-use asset and lease liability. Prior to the authoritative guidance, only capital leases were recognized on the balance sheet by les sees. The new accounting guidance , as applied by lessors , is materially consistent with current GAAP. In January 2018, the FASB issued authoritative guidance which provided an optional practical expedient to grandfather the accounting for existing and expi red land easements not accounted for as a lease under the new authoritative guidance. MGE Energy and MGE adopted this practical expedient. Th e lease authoritative guidance became effective January 1, 2019. MGE Energy and MGE adopted the standard upon the effective date. In compliance with authorized transition guidance, MGE Energy and MGE began applying the new standard on January 1, 2019, but will continue to present periods prior to that date according to the previous authoritative standard. There was no material impact on the consolidated net income or cash flows . See Footnote 3 for further lease information .

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	Leases - MGE Energy and MGE. As part of its regular operations, MGE enters into various contracts related to IT equipment, substations, cell towers, land, wind easements, and other property in use for operations. A contract is or contains a lease if the contract conveys the right to control the use of identified property, plant, or equipment for a period of time in exchange for consideration. Determination as to whether an arrangement is or contains a lease is completed at inception. Leases with an in itial term of 12 months or less are not recorded on the c onsolidated b alance s heets; lease expense for these leases are recognized on a straight-line basis over the lease term. Leases with initial terms in excess of 12 months are recorded as operating or f inancing leases o n the c onsolidated b alance s heets. Operating lease assets and operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. For leases that do not p rovide an implicit rate, a collateralized incremental borrowing rate based on the information available at commencement date, including lease term, is used in determining the present value of future payments. The operating lease asset also includes any lea se payments made and excludes lease incentives and initial direct costs incurred. Lease terms may include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. Operating lease expense is recognized on a s traight-line basis over the lease term. MGE has regulatory treatment and recognizes regulatory assets or liabilities for timing differences between when net lease costs are recorded and when costs are recognized. As of March 31, 2019 , MGE has no signifi cant leases not yet commenced that would create significant future rights and obligations. The following table shows lease expense for three months ended March 31, 2019 : (In thousands) Income Statement Location Finance lease expense: Amortization of leased assets $ 432 Depreciation and amortization Interest on lease liabilities 199 Interest expense, net Operating lease expense 27 Other operations and maintenance Total lease expense $ 658 The following table shows the lease assets and liabilities on the consolidated balance sheet as of March 31, 2019 : (In thousands) Balance Sheet Location Lease assets: Finance lease assets $ 16,976 Finance lease assets Operating lease assets 121 Other deferred assets and other Total lease assets $ 17,097 Lease liabilities: Finance lease liabilities - current $ 1,049 Other current liabilities Finance lease liabilities - long-term 17,666 Finance lease liabilities Operating lease liabilities - current 72 Other current liabilities Operating lease liabilities - long-term 85 Other deferred liabilities and other Total lease liabilities $ 18,872 The following table shows other financial lease information for the three months ended March 31, 2019 : (In thousands) Cash paid for amounts included in the measurement of lease liabilities: Finance leases - Financing cash flows $ 494 Finance leases - Operating cash flows 199 Operating leases - Operating cash flows 34 Lease assets obtained in exchange for lease liabilities: Finance leases 11,919 Operating leases - The following table shows the weighted average remaining lease terms and discount rates as of March 31, 2019 : Weighted-average remaining lease terms (in years): Finance leases 37 Operating leases 7 Weighted-average discount rates: Finance leases 4.36 % Operating leases 4.21 % The following table shows maturities of lease liabilities as of March 31, 2019 : (In thousands) Finance Operating 2019 $ 1,193 $ 58 2020 1,600 69 2021 1,385 2 2022 1,266 2 2023 1,217 2 Thereafter 41,316 52 Subtotal 47,977 185 Less: Present value discount (29,262) (28) Lease liability $ 18,715 $ 157 Future minimum rental payments as of December 31, 2018, under agreements classified as operating leases with noncancelable terms in excess of one year are as follows: (In thousands) 2019 2020 2021 2022 2023 Thereafter Minimum lease payments $ 1,646 $ 1,371 $ 1,095 $ 989 $ 975 $ 22,707

Investment in ATC and ATC Holdc

Investment in ATC and ATC Holdco	3 Months Ended
	Mar. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Investment in ATC and ATC Holdco	Investment in ATC and ATC Holdco - MGE Energy and MGE. ATC owns and operates electric transmission facilities primarily in Wisconsin. MGE received an interest in ATC when it, like other Wisconsin electric utilities, contributed its electric transmission facilities to ATC as required by Wisconsin law. That interest is presently held by MGE Transco, which, since December 1, 2016, is owned by MGE Energy. ATC Holdco was formed by several members of ATC, including MGE Energy, to pursue electric tr ansmission development and investments outside of Wisconsin. The ownership interest in ATC Holdco is held by MGEE Transco, a wholly-owned subsidiary of MGE Energy . MGE Transco and MGEE Transco have accounted for their investment s in ATC and ATC Holdco, re spectively, under the equity method of accounting. Equity earnings from investments are recorded as " Other income " on the consolidated statements of income of MGE Energy. MGE Transco recorded the follo wing : Three Months Ended March 31, (In thousands) 2019 2018 Equity earnings from investment in ATC $ 2,218 $ 2,451 Dividends from ATC (a) 2,012 - Capital contributions to ATC 178 710 (a) MGE Transco recorded a $2.3 million dividend receivable from ATC as of December 31, 2017. A cash dividend was received in January of the proceeding year. ATC Holdco was formed in December 2016. In the near term, it is expected that ATC Holdco will be pursuing transmission development opportunities that typically have long development and investment lead times before becoming operational. In April 2019, MGE Transco m ade a $ 1.1 million capital contribution to AT C. ATC ' s summarized financial data is as follows: Three Months Ended March 31, (In thousands) 2019 2018 Operating revenues $ 177,715 $ 165,429 Operating expenses (90,387) (84,893) Other income, net 260 111 Interest expense, net (29,118) (27,762) Earnings before members' income taxes $ 58,470 $ 52,885 MGE receives transmission and other related services from ATC. During the three months ended March 31, 2019 , MGE recorded $ 7.6 million for transmission services received compared to $ 7.2 million for the comparable period in 2018 . MGE also provides a variety of operational, maintenance, and project management services for ATC, which is reimbursed by ATC. As of March 31, 2019 , and December 31, 2018 , MGE had a receivable due from ATC of $ 0.1 million.

Taxes

Taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Taxes	Taxes - MGE Energy and MGE . Effective Tax Rate. The consolidated income tax provision differs from the amount computed by applying the statutory federal income tax rate to income before income taxes, as follows: MGE Energy MGE Three Months Ended March 31, 2019 2018 2019 2018 Statutory federal income tax rate 21.0 % 21.0 % 21.0 % 21.0 % State income taxes, net of federal benefit 6.3 % 6.4 % 6.2 % 6.0 % Amortized investment tax credits (0.1) % (0.1) % (0.1) % (0.1) % Credit for electricity from wind energy (a) (5.9) % (0.5) % (6.5) % (0.5) % AFUDC equity, net (0.2) % (0.4) % (0.2) % (0.4) % Amortization of utility excess deferred tax - tax reform (b) (2.4) % (1.8) % (2.6) % (2.0) % Other, net, individually insignificant 0.5 % (0.4) % 0.5 % (0.6) % Effective income tax rate 19.2 % 24.2 % 18.3 % 23.4 % (a) Saratoga Wind Farm became operational in February 2019. (b) Included are impacts of the Tax Cuts and Jobs Act for the regulated utility for excess deferred taxes recognized using a normalization method of accounting. For the three months ended March 31, 201 9 and 201 8 , MGE recognized $ 0.6 million and $ 0.5 million, respectively. The amount and timing of the cash impacts will depend on the period over which certain income tax benefits are provided t o customers, determined by the PSCW.

Pension and Other Postretiremen

Pension and Other Postretirement Plans	3 Months Ended
	Mar. 31, 2019
Compensation and Retirement Disclosure [Abstract]
Pension and Other Postretirement Plans	Pension and Other Postretirement Plans - MGE Energy and MGE. MGE maintains qualified and nonqualified pension plans, health care, and life insurance benefits. Additionally, MGE has def ined co ntribution 401(k) benefit plans. The components of net periodic benefit cost, other than the service cost component, are recorded in " Other income, net " on the consolidated statements of income. The service cost component is recorded in " Other operations and maintenance " on the consolidat ed statements of income. The service cost component of net periodic benefit cost is eligible for capitalization within the consolidated balance sheets. MGE has regulatory treatment and recognizes regulatory assets or liabilities for timing differences betw een when net periodic benefit costs are recovered and when costs are recognized. The following table presents the components of net periodic benefit costs recognized . Three Months Ended March 31, (In thousands) 2019 2018 Pension Benefits Components of net periodic benefit cost: Service cost $ 1,141 $ 1,457 Interest cost 3,452 3,208 Expected return on assets (5,547) (6,568) Amortization of: Prior service credit (28) (11) Actuarial loss 1,729 1,298 Net periodic benefit cost (credit) $ 747 $ (616) Postretirement Benefits Components of net periodic benefit cost: Service cost $ 219 $ 332 Interest cost 577 658 Expected return on assets (681) (802) Amortization of: Transition obligation 1 1 Prior service credit (667) (667) Actuarial loss 106 128 Net periodic benefit (credit) cost $ (445) $ (350)

Equity and Financing Arrangemen

Equity and Financing Arrangements	3 Months Ended
	Mar. 31, 2019
Equity and Financing Arrangements Disclosure [Abstract]
Equity and Financing Arrangements	Equity and Financing Arrangements - MGE Energy. a. Common Stock. MGE Energy sells shares of its common stock through its Stock Plan. Those shares may be newly issued shares or shares that MGE Energy has purchased in the open market for resale to participants in the Stock Plan. All sales under the Stock Plan are covered by a shelf registration statement that MGE Energy filed with the SEC. For both the three months ended March 31, 2019 and 2018 , MGE Energy did not issue any new shares of common s tock under the Stock Plan. b. Dilutive Shares Calculation. MGE Energy does not have any stock option or stock award programs or any dilutive securities.

Share-Based Compensation

Share-Based Compensation	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	Share-Based Compensation - MGE Energy and MGE. Under MGE Energy ' s Director Incentive Plan and its Performance Unit Plan, non-employee directors and eligible employees may receive performance units that entitle the holder to receive a cash payment equal to the value of a designated number of shares of MGE Energy's common stock, plus dividend equivalent payments thereon, at the end of the performance period set in the award . In 2019 , 5,175 units were gra nted under the Director Incentive Plan and are subject to a three-year graded vesting schedule, and 17,022 units were granted under the Performance Unit Plan and are subject to a five-year graded vesting schedule. On the grant d ate, the cost of the director or employee services received in exchange for a performance unit award is measured based on the current market value of MGE Energy common stock. The fair value of the awards is remeasured quarterly, including as of March 31, 2019 , as required by applicable accounting standards. Changes in fair value as well as the original grant are recognized as compensation cost. Since this amount is re measured throughout the vesting period, the compensation cost is subject to variability. For nonretirement eligible employees under the Performance Unit Plan, stock-based compensation costs are accrued and recognized using the graded vesting method. Compensation cost for retirement eligible employees or employees that will bec ome retirement eligible during the vesting schedule are recognized on an abridged horizon as retirement eligibility accelerates vesting. During the three months ended March 31, 2019 and 2018 , MGE recorded $ 1.2 millio n and $ 0.2 million, respectively, in compensation expense as a result of awards under the plans. In January 2019 , cash payments of $ 1.5 million were distributed relating to awards that were granted under the plans. No forfeitures of units occurred during the three months ended March 31, 2019 and 2018 . As of March 31, 2019 , $ 5.3 million of outstanding awards are vested. Of this amount, no cash settlements have occurred as cash payments are only made at the end of the period covered by the awards.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies . a. Environmental - MGE Energy and MGE . MGE Energy and MGE are subject to frequently changing local, state, and federal regulations concerning air quality, water quality, land use, threatened and endangered species, hazardous materials handling, and solid waste disposal. These regulations affect the manner in which they conduct their operations, the costs of those operations, as well as capital and operating expenditures. Several of these environmental rules are subje ct to legal challenges, reconsideration and/or other uncertainties. Regulatory initiatives, proposed rules, and court challenges to adopted rules have the potential to have a material effect on capital expenditures and operating costs. Management belie ves compliance costs will be recovered in future rates based on previous treatment of environmental compliance projects. These initiatives, proposed rules, and court challenges include: • The EPA's published water effluent limitations guidelines and stand ards for steam electric power plants, which focus on the reduction of metals and other pollutants in wastewater from new and existing power plants, such as the coal-burning plants at Columbia and the Elm Road Units. The operators of the Columbia and the Elm Ro ad Units have indicated that equipment upgrades may be necessary to comply with the new discharge standards. Management believes that any compliance costs will be recovered in future rates based on previous treatment of environmental compliance projects. • The EPA's cooling water intake rules, which require cooling water intake structures at electric p ower plants, such as our Blount and Columbia plants, to meet best available technology standards so that mortality from entrainment (drawing aquatic life int o a plant's cooling system) and impingement (trapping aquatic life on screens) are reduced. MGE expects that the Section 316(b) rule will not have a material effect on its existing plants. • Greenhouse Gas (GHG) reduction guidelines and approval criteria established under the Clean Air Act for states to use in developing plans to control GHG emissions from existing fossil fuel-fired electric generating units (EGUs). In 2015, the EPA finalized the Clean Power Plan (CPP) which directed states to submit plans, to reduce GHG emissions from the electric generation sector. In February 2016, the U.S. Supreme Court stayed implementation of the CPP and the stay remains in effect. In October 2017, the EP A issued a proposed rule to repeal the CPP. In August 2018, the EPA proposed the Affordable Clean Energy (ACE) rule which would replace the CPP, if successfully implemented. The ACE proposal directs states to submit plans to the EPA for approval that imple ment standards of performance (called Best System of Emissions Reductions, or BSER) for individual EGUs over 25 MW. ACE defines BSER as on-site, heat-rate efficiency improvements, whereas the CPP defines BSERs using carbon dioxide emission performance rate s. Simple cycle units such as our smaller combustion units, and combined cycle units such as our WCCF are exempt from the proposed ACE rule. Under the proposed ACE rule, if a state fails to prepare a plan, or its plan is not approved by the EPA a federal i mplementation plan will be issued for that state. The proposed ACE rule as it is currently written has the potential to impact Blount, Columbia, and the Elm Road Units. Given the pending legal proceedings, and the proposed ACE rule, the nature and timin g of any final requirements is subject to uncertainty. MGE is unable to determine with any certainty the impact of the proposed ACE rule on our operations. If an ACE rule is implemented substantially in the form of the CPP rule, it is expected to have a ma terial impact on MGE. MGE will continue to monitor developments with the proposed ACE rule, and the CPP rule, and related litigation. • The EPA's rule to regulate ambient levels of ozone through the 2015 Ozone National Ambient Air Quality Standards (NAAQS ). In May 2018, the EPA issued a final rule which designated the northeast portion of Milwaukee County as being in nonattainment with this NAAQS. The Elm Road Units are located in Milwaukee County, outside the designated nonattainment area. In August 2018, several environmental groups, the City of Chicago, and the State of Illinois filed federal lawsuits challenging several of the EPA's attainment designation decisions, including the partial Milwaukee County designation as being too narrow and not sufficien tly protective. MGE is monitoring the outcome of this lawsuit and how it may affect our Elm Road Units in Milwaukee County. At this time , MGE expects that the 2015 Ozone NAAQS will not have a material effect on its existing plants based on final designatio ns. • Rules regulating nitrogen oxide (NO x ) and sulfur dioxide (SO 2 ) emissions, including the Cross State Air Pollution Rule (CSAPR) and Clean Air Visibility Rule (CAVR). MGE has met our CSAPR obligations in 2018 and 2017 through a combination of reduced emissions through pollution control (e.g. SCR installation at Columbia), as well as owned, received, and purchased allowances. There remains uncertainty around CSAPR due to legal challenges, however, MGE expects that we will meet ongoing CSAPR obligations for the foreseeable future. MGE will continue to monitor developments and litigation to this rule. Columbia is subject to the best available retrofit technology (BART) reg ulations, a subsection of the EPA's CAVR, which may require pollution control retrofits. Columbia's existing pollution control upgrades, and the EPA's stance that compliance with the CSAPR equals compliance with BART, should mean that Columbia will not nee d to do additional work to meet BART requirements. At this time, however, the BART regulatory obligations, compliance strategies, and costs remain uncertain in Wisconsin due to the continued legal challenges surrounding CSAPR and CAVR. MGE will continue to monitor developments to this rule. • The EPA's Coal Combustion Residuals Rule (CCR), which regulates coal ash from burning coal for the purpose of generating electricity as a solid waste, and defines what ash use activities would be considered generally exempt beneficial reuse of coal ash. The CCR rule also regulates landfills, ash ponds, and other surface impoundments used for coal combustion residuals by regulating their design, location, monitoring, and operation. Review of the Elm Road Units has ind icated that the costs to comply with this rule are not expected to be significant. Columbia's operator has completed a review of their system and has determined that an onsite ash pond will need to be closed and replaced with a dry ash handling system. The dry ash handling system installation is planned for 2020-2021. In July 2018, the EPA published a final rule that included amendments to the CCR (which include the allowance of alternative performance standards for landfills and surface impoundments, revised risk-based groundwater protection standards, and an extension of the deadline by which certain facilities must cease the placement of waste in CCR units). In August 2018, the Court of Appeals for the D.C. Circuit vacated parts of the CCR for not being sufficiently protective of the environment. It is unclear how the EPA will respond to that decision. MGE will continue to monitor potential rule modifications to assess potential impacts on operations. b. Legal Matters - MGE Energy and MGE. MGE is involved in various legal matters that are being defended and handled in the normal course of business . MGE maintains accruals for such costs that are probable of being incurred and subject to reasonable estimation. The accrued amount for these matters is not material to the financial statements. MGE does not expect the resolution of these matters to have a material adverse effect on its consolidated results of operations, financial condition, or cash flows .

Rate Matters

Rate Matters	3 Months Ended
	Mar. 31, 2019
Regulated Operations [Abstract]
Rate Matters	Rate Matters - MGE Energy and MGE. a. Rate P roceedings. In December 2018, the PSCW approved the settlement agreement between MGE and intervening parties in the rate case. The settlement decrease s electric rates by 2.24 % , or $ 9.2 million, in 2019. MGE will maintain this rate level for 2020, with the exception that MGE will file a 2020 Fuel Cost Plan in 2019 and MGE's electric rates will be adjusted accordingly. The decrease reflects the ongoing tax imp acts of the Tax Act and the addition of lower-cost renewable generation capacity. The settlement agreement increases gas rates by 1.06 %, or $ 1.7 million, in 2019 and 1.46 %, or $ 2.4 million, in 2020. The gas increase covers infrastructure costs. It also reflects the impacts of the Tax Act. The return on common stock equity for 2019 and 2020 is 9.8 % based on a capital structure consisting of 56.6 % common equity in 2019 and 56.1 % common equity in 20 20 . MGE did not file a base rate case for 2018 . b. Fuel R ules. Fuel rules require the PSCW and Wisconsin utilities to defer electric fuel-related costs that fall outside a symmetrical cost tolerance band around the amount approved for a utility in its annual fuel proceedings. Any over/under recovery of the actual costs is determined in the following year and is then reflected in future billings to electric retail customers. The fuel rules bandwidth is currently set at plus or minus 2 %. Under fuel rules, MGE would defer costs, les s any excess revenues, if its actual electric fuel costs exceeded 102 % of the electric fuel costs allowed in its latest rate order. Excess revenues are defined as revenues in the year in question that provide MGE with a greater ret urn on common equity than authorized by the PSCW in MGE's latest rate order. Conversely, MGE is required to defer the benefit of lower costs if actual electric fuel costs were less than 98 % of the electric fuel costs allowed in th at order. These costs will be subject to the PSCW's annual review of fuel costs completed in the year following the deferral. In December 2017, the PSCW approved a surcharge for 2018 electric fuel-related costs. The surcharge increased electric retail rev enue in 2018 by $ 0.5 million, or 0.13 %. As of March 31, 2019 , MGE had no 2019 fuel savings deferred . As of December 31, 2018 , MGE had deferred $ 9.5 million of 2018 fuel savings . The 2018 fuel savings will be subject to the PSCW ' s annual review of fuel costs, expected to be completed in 2019.

Derivative and Hedging Instrume

Derivative and Hedging Instruments	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative and Hedging Instruments	Derivative and Hedging Instruments - MGE Energy and MGE. a. Purpose. As part 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 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 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 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 loss or net gain posi 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 ates as a component of the fuel rules mechanism . b. Notional Amounts. The gross notional volume of open derivatives is as follows: March 31, 2019 December 31, 2018 Commodity derivative contracts 440,440 MWh 386,440 MWh Commodity derivative contracts 2,871,760 Dth 5,260,000 Dth FTRs 844 MW 2,252 MW PPA 1,900 MW 2,050 MW c . Financial Statement Presentation . MGE purchases and sells exchange-traded and over-the-counter options, swaps, and future contracts. These arrangements are primarily entered into to help stabilize the price risk associated with gas or power purchases. These transactions are employed by both MGE ' s gas and electric segments. Additionally, as a result of the firm transmission agreements that MGE holds on electricity transmission paths in the MISO market, MGE holds financial transmission rights (FTRs). An FTR is a financial instrument that entitles the holder to a stream of revenues or charges based on the differences in hourly day-ahead energy prices between two p oints on the transmission grid. The fair values of these instruments are offset with a corresp onding regulatory asset/liability depending on whether they are in a net loss/gain position. Depending on the nature of the instrument, the gain or loss associated with these transactions will be reflected as cost of gas sold, fuel for electric generation, or purchased power expense in the delivery month applicable to the instrument. As of March 31, 2019 , and December 31 , 2018 , the fair value of exchange traded derivatives and FTRs exceeded their cost basis by $ 0.6 million and $ 0.7 million, respectively. MGE is a party to a purchased power agreement that provides MGE with firm capacity and energy during a base term from June 1, 2012, through May 31, 2022. The agreement also allows MGE an option to extend the contract after the base term. The agreement is accounted for as a derivative contract and is recognized at its fair value on the consolidated balance sheet s . However, the derivative qualifies for regulatory deferral and is recognized with a corresponding regulatory asset or liability depending on whether the fair value is in a loss or gain position. The fair value of the contract as of March 31, 2019 , and December 31, 2018 , reflects a loss position of $ 31.6 million and $ 32.5 million, respectively. The actual cost will be recognized in purchased power e xpense in the month of purchase. The following table summarizes the fai r value of the derivative instruments on the consolidated balance sheet s . All derivative instruments in this table are presented on a gross basis and are calculated prior to the netting of instruments with the same counterparty under a master netting agree ment as well as the netting of collatera l. For financial statement purposes, instruments are netted with the same counterparty under a master netting agreement as well as the netting of collatera l . As of March 31, 2019 , and December 31, 2018 , the rec eivable margin account balance of $ 1.6 million and $ 1.2 million, respectively, is shown net of any collateral posted against derivative positions. Derivative Derivative (In thousands) Assets Liabilities Balance Sheet Location March 31, 2019 Commodity derivative contracts $ 546 $ 114 Other current assets Commodity derivative contracts 129 98 Other deferred charges FTRs 124 - Other current assets PPA N/A 8,730 Derivative liability (current) PPA N/A 22,880 Derivative liability (long-term) December 31, 2018 Commodity derivative contracts $ 727 $ 270 Other current assets Commodity derivative contracts 74 72 Other deferred charges FTRs 241 - Other current assets PPA N/A 8,550 Derivative liability (current) PPA N/A 23,980 Derivative liability (long-term) The foll owing tables show the ef fect of netting arrangements for recognized derivative assets and liabilities that are subject to a master netting arr angement or similar arrangement on the consolidated balance sheets. Offsetting of Derivative Assets (In thousands) Gross Amounts Gross Amounts Offset in Balance Sheets Collateral Posted Against Derivative Positions Net Amount Presented in Balance Sheets March 31, 2019 Commodity derivative contracts $ 675 $ (212) $ - $ 463 FTRs 124 - - 124 December 31, 2018 Commodity derivative contracts $ 801 $ (342) $ - $ 459 FTRs 241 - - 241 Offsetting of Derivative Liabilities (In thousands) Gross Amounts Gross Amounts Offset in Balance Sheets Collateral Posted Against Derivative Positions Net Amount Presented in Balance Sheets March 31, 2019 Commodity derivative contracts $ 212 $ (212) $ - $ - PPA 31,610 - - 31,610 December 31, 2018 Commodity derivative contracts $ 342 $ (342) $ - $ - PPA 32,530 - - 32,530 The following table s summarize the unrealized and realized gains (losses) related to the derivative instruments on the consolidated balance sheet s and the consolidated statements of income . 2019 2018 (In thousands) Current and Long-Term Regulatory Asset Other Current Assets Current and Long-Term Regulatory Asset Other Current Assets Three Months Ended March 31: Balance at January 1, $ 31,830 $ 377 $ 41,958 $ 806 Unrealized (gain) loss (922) - 128 - Realized (loss) gain reclassified to a deferred account (260) 260 (158) 158 Realized gain (loss) reclassified to income statement 375 (378) (687) (645) Balance at March 31, $ 31,023 $ 259 $ 41,241 $ 319 Realized losses (gains) 2019 2018 (In thousands) Fuel for Electric Generation/ Purchased Power Cost of Gas Sold Fuel for Electric Generation/ Purchased Power Cost of Gas Sold Three Months Ended March 31: Commodity derivative contracts $ 270 $ 277 $ 374 $ 615 FTRs (135) - (175) - PPA (409) - 518 - MGE's commodity derivativ e contracts, FTRs, and PPA are subject to regulatory deferral. These derivatives are marked to fair value and are offset with a corresponding regulatory asset or liability. Realized gains and losses are deferred on the consolidated balance sheet s and are recognized in earnings in the delivery month applicable to the instrument. As a result of the above described treatment, there are no unrealized gains or losses that flow through earnings. The PPA has a provision that may require MGE to post collateral if MGE's debt rating falls below investment grade (i.e., below BBB-). The amount of collateral that it may be required to post varies from $ 20.0 million to $ 40.0 million, depending on MGE's nominated capacity amount. As of March 31, 2019 , no collateral is required to be, or has been, posted. Certain counterparties extend MGE a credit limit. If MGE exceeds these limits, the counterparties may require collateral to be pos ted. As of March 31, 2019 and December 31, 2018 , no counterparties were in a net liability position. Nonperformance of counterparties to the non-exchange traded derivatives could expose MGE to credit loss. However, MGE enters into transactions only with companies that meet or exceed strict credit guidelines, and it monitors these counterparties on an ongoing basis to mitigate nonperformance risk in its portfolio. As of March 31, 2019 , no counterparties have defaulted.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments - MGE Energy and MGE. Fair value is defined as the price that would be received to sell an asset or would be paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. The accounting standard clarifies that fair value should be based on the assumptions market participants would use when pricing the asset or liability including ass umptions about risk. The st andard also establishes a three- level fair value hierarchy based upon the observability of the assumptions used and requires the use of observable market data when available. The levels are: Level 1 - Pricing inputs are quoted p rices within active markets for identical assets or liabilities. Level 2 - Pricing inputs are quoted prices within active markets for similar assets or liabilities; quoted prices for identical or similar instruments in markets that are not active; and mod el-derived valuations that are correlated with or otherwise verifiable by observable market data. Level 3 - Pricing inputs are unobservable and reflect management ' s best estimate of what market participants would use in pricing the asset or liability. a. Fair Value of Financial Assets and Liabilities Recorded at the Carrying Amount. T he carrying amount of cash , cash equivalents, and outstanding commercial paper approximates fair market value due to the short maturity of those investments and obligations. The estimated fair market value of long-term debt is based on quoted market prices for similar financial instruments . Since long-term debt is not traded in an active market, it is classified as Level 2. The estimated fair market value of financial instruments are as follows: March 31, 2019 December 31, 2018 (In thousands) Carrying Amount Fair Value Carrying Amount Fair Value MGE Energy Assets: Cash and cash equivalents $ 82,402 $ 82,402 $ 83,102 $ 83,102 Liabilities: Short-term debt - commercial paper 6,000 6,000 13,000 13,000 Long-term debt (a) 501,303 553,598 502,431 518,811 MGE Assets: Cash and cash equivalents $ 9,624 $ 9,624 $ 4,843 $ 4,843 Liabilities: Short-term debt - commercial paper 6,000 6,000 13,000 13,000 Long-term debt (a) 501,303 553,598 502,431 518,811 (a) Includes long-term debt due within one year. Excludes debt issuance costs and unamortized discount of $4.4 million and $4.5 million as of March 31, 2019, and December 31, 2018, respectively. b. Recurring Fair Value Measurements. The following table presents the balances of assets and liabilities measured at fair value on a recurr ing basis . Fair Value as of March 31, 2019 (In thousands) Total Level 1 Level 2 Level 3 MGE Energy Assets: Derivatives, net $ 799 $ 316 $ - $ 483 Exchange-traded investments 963 963 - - Total Assets $ 1,762 $ 1,279 $ - $ 483 Liabilities: Derivatives, net $ 31,822 $ 56 $ - $ 31,766 Deferred compensation 3,009 - 3,009 - Total Liabilities $ 34,831 $ 56 $ 3,009 $ 31,766 MGE Assets: Derivatives, net $ 799 $ 316 $ - $ 483 Exchange-traded investments 70 70 - - Total Assets $ 869 $ 386 $ - $ 483 Liabilities: Derivatives, net $ 31,822 $ 56 $ - $ 31,766 Deferred compensation 3,009 - 3,009 - Total Liabilities $ 34,831 $ 56 $ 3,009 $ 31,766 Fair Value as of December 31, 2018 (In thousands) Total Level 1 Level 2 Level 3 MGE Energy Assets: Derivatives, net $ 1,042 $ 296 $ - $ 746 Exchange-traded investments 848 848 - - Total Assets $ 1,890 $ 1,144 $ - $ 746 Liabilities: Derivatives, net $ 32,872 $ 124 $ - $ 32,748 Deferred compensation 3,078 - 3,078 - Total Liabilities $ 35,950 $ 124 $ 3,078 $ 32,748 MGE Assets: Derivatives, net $ 1,042 $ 296 $ - $ 746 Exchange-traded investments 43 43 - - Total Assets $ 1,085 $ 339 $ - $ 746 Liabilities: Derivatives, net $ 32,872 $ 124 $ - $ 32,748 Deferred compensation 3,078 - 3,078 - Total Liabilities $ 35,950 $ 124 $ 3,078 $ 32,748 No transfers were made in or out of Level 1 or Level 2 for the three months ended March 31, 2019 . I nvestments include exchange-traded investment securities valued using quoted prices on active exchanges and are therefore classified as Level 1. Derivatives include exchange-traded derivative c ontracts, over-the-counter transactions, a purchased power agreement, and FTRs. Most exchange-traded derivative contracts are valued based on unadjusted quoted prices in active markets and are therefore class ified as Level 1. A small number of exchange-traded derivative contracts are valued using quoted market pricing in markets with insufficient volumes and are therefore considered unobservable and classified as Level 3. Transactions done with an over-the-cou nter party are on inactive markets and are therefore classified as Level 3. These transactions are valued based on quoted prices from markets with similar exchange - traded transactions. FTRs are priced based upon monthly auction results for identical or sim ilar instruments in a closed market with limited data available and are therefore classified as Level 3. The purchased power agreement (see Footnote 11 ) was valued using an internally-developed pricing model and therefore is classified as Level 3. The model projects future market energy prices and compares those prices to the projected power costs to be incurred under the contract. Inputs to the model require significant management judgmen t and estimation. Future energy prices are based on a forward power pricing curve using exchange-traded contracts in the electric futures market . A basis adjustment is applied to the market energy price to reflect the price differential between the market price delivery point and the counterpa rty delivery point. The historical relationship between the delivery points is reviewed and a discount (below 100%) or premium (above 100%) is derived. This comparison is done for both peak times when demand is high and off- peak times when demand is low. I f the basis adjustment is lowered, the fair value measurement will decrease, and if the basis adjustment is increased, the fair value measurement will increase. The projected power costs anticipated to be incurred under the purchased power agreement are d etermined using many factors, including historical generating costs, future prices, and expected fuel mix of the counterparty. An increase in the projected fuel costs would result in a decrease in the fair value measurement of the purchased power agreement . A significant input that MGE estimates is the counterparty ' s fuel mix in determining the projected power cost. MGE also considers the assumptions that market participants would use in valuing the asset or liability. This consideration includes assumption s about market risk such as liquidity, volatility , and contract duration. The fair value model uses a discount rate that incorporates discounting, credit, and model risks. The following table presents the significant unobservable inputs used in the pricin g model. Model Input Significant Unobservable Inputs March 31, 2019 December 31, 2018 Basis adjustment: On peak 92.1 % 92.1 % Off peak 92.5 % 92.8 % Counterparty fuel mix: Internal generation 40% - 60% 50% - 75% Purchased power 60% - 40% 50% - 25% The deferred compensation plan allows participants to defer certain cash compensation into a notional investment account. These amounts are included within other deferred liabilities in the consolidated balance sheets . The notional investments earn interest based upon the semiannual rate of U.S. Treasury Bills having a 26 -w eek maturity increased by 1 % compounded monthly with a minimum annual rate of 7 %, compounded monthly. The notional investments are based upon observable market data , however, since the deferred compensation obligations themselves are not exchanged in an active market, they are classified as Level 2 . The following table summarizes the changes in Level 3 commodity derivative assets and liabilities measured at fair value on a recurring b asis . Three Months Ended March 31, (In thousands) 2019 2018 Beginning balance $ (32,002) $ (42,026) Realized and unrealized gains (losses): Included in regulatory assets 719 563 Included in other comprehensive income - - Included in earnings (644) (542) Included in current assets 173 (173) Purchases 5,765 5,834 Sales - - Issuances - - Settlements (5,294) (5,119) Transfers in and/or out of Level 3 - - Balance as of March 31, $ (31,283) $ (41,463) Total gains (losses) included in earnings attributed to the change in unrealized gains (losses) related to assets and liabilities held at March 31, (b) $ - $ - The following table presents total realized and unrealized gains ( losses ) inc luded in income for Level 3 assets and liabilities measured at fair value on a recurring basis (b ) . Three Months Ended March 31, (In thousands) 2019 2018 Purchased power expense $ (556) $ (723) Cost of gas sold expense (88) 181 Total $ (644) $ (542) (b ) MGE's exchange-traded derivative contracts, over-the-counter party transactions, purchased power agreement, and FTRs are subject to regulatory deferral. These derivatives are therefore marked to fair value and are offset in the financial statements with a corresponding regulatory asset or liability.

Asset Retirement Obligation

Asset Retirement Obligation	3 Months Ended
	Mar. 31, 2019
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligation	Asset Retirement Obligation - MGE Energy and MGE. A liability for the fair value of an asset retirement obligation (ARO) is recognized in the period in which it is incurred if it can be reasonably estimated. The offsetting associated asset retirement costs are capitalized as a long-lived asset and depreciated over the asset's useful life. As of March 31, 2019 , MGE recorded an obligation of $ 1.5 million for the fair value of its legal liability for an ARO associated with the Saratoga Wind Farm . MGE has regulatory treatment and recognizes regulatory assets or liabilities for the timing differences between when we recover legal AROs in rates and when those costs would actually be recognized.

Revenue

Revenue	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer	Revenue - MGE Energy and MGE. Revenues disaggregated by revenue source were as follows: Three Months Ended (In thousands) March 31, Electric revenues 2019 2018 Residential $ 34,581 $ 33,259 Commercial 49,253 47,452 Industrial 2,931 2,895 Other-retail/municipal 8,239 8,287 Total retail 95,004 91,893 Sales to the market 1,961 2,034 Other revenues 451 464 Total electric revenues 97,416 94,391 Gas revenues Residential 40,317 36,551 Commercial/Industrial 28,125 24,952 Total retail 68,442 61,503 Gas transportation 1,536 1,135 Other revenues 122 127 Total gas revenues 70,100 62,765 Nonregulated energy revenues 53 476 Total Operating Revenue $ 167,569 $ 157,632 Performance Obligations A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account. A contract's transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. The majority of MGE Energy's and MGE's contracts have a single performance obligation. Retail Revenue (Residential, Commercial, Industrial, and Other Retail/Municipal) Retail reve nue of electric and gas utility service represent MGE's core business activities. Tariffs are approved by the PSCW through a rate order and provide MGE's customers with the standard terms and conditions, including pricing terms. The performance obligation to deliver electricity or gas is satisfied over time as the customer simultaneously receives and consumes the commodities provided by MGE. MGE recognizes revenues as the commodity is delivered to customers. Meters are read on a systematic basis throughout the month based on established meter-reading schedules and the customer is subsequently billed for their services. At the end of the month, MGE accrues an estimate for the unbilled amount of commodities delivered to customers. The unbilled revenue estimate is based on daily system demand volumes, weather factors, estimated line losses, estimated customer usage by class, and applicable customer rates. Utility Cost Recovery Mechanisms MGE's tariff rates include a provision for fuel cost recovery. The PSCW a llows Wisconsin utilities to defer electric fuel-related costs, less excess revenues, that fall outside a symmetrical cost tolerance band. Any over/under recovery of the actual costs in a given year is determined in the following year and is then reflected in future billings to electric retail customers. Over-collection of fuel-related costs that are outside the approved range will be recognized as a reduction of revenue. Under-collection of these costs will be recognized in "Purchased power" expense in the consolidated statements of income. The cumulative effects of these deferred amounts will be recorded in "Regulatory assets" or "Regulatory liabilities" on the consolidated balance sheets until they are reflected in future billings to customers. See Footn ote 10.b. for further information. MGE received a PSCW order in January 2018 to defer the over-collection of income tax expense collected in customer rates during 2018 as a result of the Tax Cuts and Jobs Act (the Tax Act) reduction in the income tax rate to 21 percent. MGE has other cost recovery mechanisms. For example, any over-collection of the difference between actual costs incurred and the amount of costs collected from customers is recorded as a reduction of revenue in the period incurred. Sales to the Market Sales to the market include energy charges, capacity or demand charges, and ancillary charges represented by wholesale sales of electricity made to third parties who are not ultimate users of the electricity. Most of these sales are spot market transactions on the markets operated by MISO. Each transaction is considered a performance obligation and revenue is recognized in the period in which energy charges, capacity or demand charges, and ancillary services are so ld into MISO. MGE reports, on a net basis, transactions on the MISO markets in which it buys and sells power within the same hour to meet electric energy delivery requirements. Transportation of Gas MGE has contracts under which MGE provides gas transpor tation services to customers who have elected to purchase gas from a third party and have the gas delivered via pipelines within MGE's service territory. Revenue is recognized as service is rendered or gas is delivered to customers. Tariffs are approved by the PSCW through a rate order and provide gas transportation customers with the standard terms and conditions, including pricing terms.

Segment Information

Segment Information	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Segment Information	Segment Information - MGE Energy and MGE. MGE Energy operates in the following business segments: electric utility, gas utility, nonregulated energy, transmission investment, and all other. See the 2018 Annual Report on Form 10-K for additional discussion of each of these segments. The following table s show segment information for MGE Energy ' s operations for the indicated periods : (In thousands) MGE Energy Electric Gas Nonregulated Energy Transmission Investment All Others Consolidation/ Elimination Entries Consolidated Total Three Months Ended March 31, 2019 Operating revenues $ 97,416 $ 70,100 $ 53 $ - $ - $ - $ 167,569 Interdepartmental revenues 199 4,962 9,973 - - (15,134) - Total operating revenues 97,615 75,062 10,026 - - (15,134) 167,569 Depreciation and amortization (12,509) (2,760) (1,870) - - - (17,139) Other operating expenses (73,294) (61,438) (48) - (272) 15,134 (119,918) Operating income (loss) 11,812 10,864 8,108 - (272) - 30,512 Other income, net 1,653 554 - 2,168 476 - 4,851 Interest (expense) income, net (3,665) (1,040) (1,290) - 348 - (5,647) Income before taxes 9,800 10,378 6,818 2,168 552 - 29,716 Income tax provision (451) (2,618) (1,857) (591) (192) - (5,709) Net income $ 9,349 $ 7,760 $ 4,961 $ 1,577 $ 360 $ - $ 24,007 Three Months Ended March 31, 2018 Operating revenues $ 94,391 $ 62,765 $ 476 $ - $ - $ - $ 157,632 Interdepartmental revenues 31 4,347 9,820 - - (14,198) - Total operating revenues 94,422 67,112 10,296 - - (14,198) 157,632 Depreciation and amortization (9,378) (2,395) (1,850) - - - (13,623) Other operating expenses (76,575) (55,195) (43) (3) (203) 14,198 (117,821) Operating income (loss) 8,469 9,522 8,403 (3) (203) - 26,188 Other income, net 1,730 766 - 2,372 51 - 4,919 Interest (expense) income, net (2,867) (839) (1,348) - 315 - (4,739) Income before taxes 7,332 9,449 7,055 2,369 163 - 26,368 Income tax provision (1,200) (2,458) (1,922) (648) (139) - (6,367) Net income $ 6,132 $ 6,991 $ 5,133 $ 1,721 $ 24 $ - $ 20,001 The following table s show segment information for MGE ' s operations for the indicated periods : (In thousands) MGE Electric Gas Nonregulated Energy Consolidation/ Elimination Entries Consolidated Total Three Months Ended March 31, 2019 Operating revenues $ 97,416 $ 70,100 $ 53 $ - $ 167,569 Interdepartmental revenues 199 4,962 9,973 (15,134) - Total operating revenues 97,615 75,062 10,026 (15,134) 167,569 Depreciation and amortization (12,509) (2,760) (1,870) - (17,139) Other operating expenses (73,294) (61,438) (48) 15,134 (119,646) Operating income 11,812 10,864 8,108 - 30,784 Other income, net 1,653 554 - - 2,207 Interest expense, net (3,665) (1,040) (1,290) - (5,995) Income before taxes 9,800 10,378 6,818 - 26,996 Income tax provision (451) (2,618) (1,857) - (4,926) Net income 9,349 7,760 4,961 - 22,070 Less: Net income attributable to noncontrolling interest, net of tax - - - (5,490) (5,490) Net income attributable to MGE $ 9,349 $ 7,760 $ 4,961 $ (5,490) $ 16,580 Three Months Ended March 31, 2018 Operating revenues $ 94,391 $ 62,765 $ 476 $ - $ 157,632 Interdepartmental revenues 31 4,347 9,820 (14,198) - Total operating revenues 94,422 67,112 10,296 (14,198) 157,632 Depreciation and amortization (9,378) (2,395) (1,850) - (13,623) Other operating expenses (76,575) (55,195) (43) 14,198 (117,615) Operating income 8,469 9,522 8,403 - 26,394 Other income, net 1,731 766 - - 2,497 Interest expense, net (2,867) (839) (1,348) - (5,054) Income before taxes 7,333 9,449 7,055 - 23,837 Income tax provision (1,201) (2,458) (1,922) - (5,581) Net income 6,132 6,991 5,133 - 18,256 Less: Net income attributable to noncontrolling interest, net of tax - - - (5,806) (5,806) Net income attributable to MGE $ 6,132 $ 6,991 $ 5,133 $ (5,806) $ 12,450 The following table shows segment information for assets and capital expenditures: Utility Consolidated (In thousands) MGE Energy Electric Gas Nonregulated Energy Transmission Investment All Others Consolidation/ Elimination Entries Total Assets: March 31, 2019 $ 1,223,815 $ 368,043 $ 262,979 $ 66,720 $ 461,159 $ (379,150) $ 2,003,566 December 31, 2018 1,193,083 377,005 265,301 66,366 465,661 (378,798) 1,988,618 Capital Expenditures: Three months ended March 31, 2019 $ 24,095 $ 7,145 $ 693 $ - $ - $ - $ 31,933 Year ended Dec. 31, 2018 176,399 30,497 5,301 - - - 212,197 Utility Consolidated (In thousands) MGE Electric Gas Nonregulated Energy Elimination Entries Total Assets: March 31, 2019 $ 1,223,815 $ 368,043 $ 262,929 $ (990) $ 1,853,797 December 31, 2018 1,193,083 377,005 265,251 (448) 1,834,891 Capital Expenditures: Three months ended March 31, 2019 $ 24,095 $ 7,145 $ 693 $ - $ 31,933 Year ended Dec. 31, 2018 176,399 30,497 5,301 - 212,197

Significant Accounting Policies

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Variable Interest Entities	MGE Power Elm Road and MGE Power West Campus own electric generating assets and lease those assets to MGE. Both entities are variable interest entities under applicable authoritative accounting guidance. MGE is considered the primary beneficiary of these entities as a result of contractual agreement s. As a result, MGE has consolidated MGE Power Elm Road and MGE Power West Campus .
Cash and Cash Equivalents	Cash Equivalents MGE Energy and MGE consider all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents.
Restricted Cash	Restricted Cash MGE has certain cash accounts that are restricted to uses other than current operations and designated for a specific purpose. MGE's restricted cash accounts include cash held by trustees for certain employee benefits and cash deposits held by third parties. These are included in "Other current assets" on the consolidated balance s heets.
Receivable Margin Account	Receivable – Margin Account Cash balances held by counterparties as margin collateral for certain financial transactions are recorded as receivable – margin account in "Other current assets" on the consolidated balance sheets. The costs being hedged are fuel for electric generation, purchased power, and cost of gas sold.
New Accounting Pronouncements Disclosure	New Accounting Standards - MGE Energy and MGE. Recently Adopted Leases. In February 2016, the FASB issued authoritative guidance within the c odification's Leases topic that provides guidance on the classification, recognition, measurement, and disclosure of leases. The new leasing standard establishes that a lease conveys the right to control the use of identified property, plant, or equipment for a period of time in exchange for consideration. Under the new guidance, lessees are required to rec ognize all leases with terms greater than one year, including operating leases, on the balance sheet by recording a right-of-use asset and lease liability. Prior to the authoritative guidance, only capital leases were recognized on the balance sheet by les sees. The new accounting guidance , as applied by lessors , is materially consistent with current GAAP. In January 2018, the FASB issued authoritative guidance which provided an optional practical expedient to grandfather the accounting for existing and expi red land easements not accounted for as a lease under the new authoritative guidance. MGE Energy and MGE adopted this practical expedient. Th e lease authoritative guidance became effective January 1, 2019. MGE Energy and MGE adopted the standard upon the effective date. In compliance with authorized transition guidance, MGE Energy and MGE began applying the new standard on January 1, 2019, but will continue to present periods prior to that date according to the previous authoritative standard. There was no material impact on the consolidated net income or cash flows . See Footnote 3 for further lease information .
Leases	As part of its regular operations, MGE enters into various contracts related to IT equipment, substations, cell towers, land, wind easements, and other property in use for operations. A contract is or contains a lease if the contract conveys the right to control the use of identified property, plant, or equipment for a period of time in exchange for consideration. Determination as to whether an arrangement is or contains a lease is completed at inception. Leases with an in itial term of 12 months or less are not recorded on the c onsolidated b alance s heets; lease expense for these leases are recognized on a straight-line basis over the lease term. Leases with initial terms in excess of 12 months are recorded as operating or f inancing leases o n the c onsolidated b alance s heets. Operating lease assets and operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at commencement date. For leases that do not p rovide an implicit rate, a collateralized incremental borrowing rate based on the information available at commencement date, including lease term, is used in determining the present value of future payments. The operating lease asset also includes any lea se payments made and excludes lease incentives and initial direct costs incurred. Lease terms may include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. Operating lease expense is recognized on a s traight-line basis over the lease term. MGE has regulatory treatment and recognizes regulatory assets or liabilities for timing differences between when net lease costs are recorded and when costs are recognized. As of March 31, 2019 , MGE has no signifi cant leases not yet commenced that would create significant future rights and obligations.
Investments - ATC and ATC Holdco	MGE Transco and MGEE Transco have accounted for their investment s in ATC and ATC Holdco, re spectively, under the equity method of accounting.
Pension and Other Postretirement Benefit Plan Assets	MGE maintains qualified and nonqualified pension plans, health care, and life insurance benefits. Additionally, MGE has def ined co ntribution 401(k) benefit plans. The components of net periodic benefit cost, other than the service cost component, are recorded in " Other income, net " on the consolidated statements of income. The service cost component is recorded in " Other operations and maintenance " on the consolidat ed statements of income. The service cost component of net periodic benefit cost is eligible for capitalization within the consolidated balance sheets. MGE has regulatory treatment and recognizes regulatory assets or liabilities for timing differences betw een when net periodic benefit costs are recovered and when costs are recognized.
Common Stock	MGE Energy sells shares of its common stock through its Stock Plan. Those shares may be newly issued shares or shares that MGE Energy has purchased in the open market for resale to participants in the Stock Plan. All sales under the Stock Plan are covered by a shelf registration statement that MGE Energy filed with the SEC.
Share-based Compensation	Under MGE Energy ' s Director Incentive Plan and its Performance Unit Plan, non-employee directors and eligible employees may receive performance units that entitle the holder to receive a cash payment equal to the value of a designated number of shares of MGE Energy's common stock, plus dividend equivalent payments thereon, at the end of the performance period set in the award . In 2019 , 5,175 units were gra nted under the Director Incentive Plan and are subject to a three-year graded vesting schedule, and 17,022 units were granted under the Performance Unit Plan and are subject to a five-year graded vesting schedule. On the grant d ate, the cost of the director or employee services received in exchange for a performance unit award is measured based on the current market value of MGE Energy common stock. The fair value of the awards is remeasured quarterly, including as of March 31, 2019 , as required by applicable accounting standards. Changes in fair value as well as the original grant are recognized as compensation cost. Since this amount is re measured throughout the vesting period, the compensation cost is subject to variability. For nonretirement eligible employees under the Performance Unit Plan, stock-based compensation costs are accrued and recognized using the graded vesting method. Compensation cost for retirement eligible employees or employees that will bec ome retirement eligible during the vesting schedule are recognized on an abridged horizon as retirement eligibility accelerates vesting.
Wisconsin Fuel Rules	Fuel rules require the PSCW and Wisconsin utilities to defer electric fuel-related costs that fall outside a symmetrical cost tolerance band around the amount approved for a utility in its annual fuel proceedings. Any over/under recovery of the actual costs is determined in the following year and is then reflected in future billings to electric retail customers. The fuel rules bandwidth is currently set at plus or minus 2 %. Under fuel rules, MGE would defer costs, les s any excess revenues, if its actual electric fuel costs exceeded 102 % of the electric fuel costs allowed in its latest rate order. Excess revenues are defined as revenues in the year in question that provide MGE with a greater ret urn on common equity than authorized by the PSCW in MGE's latest rate order. Conversely, MGE is required to defer the benefit of lower costs if actual electric fuel costs were less than 98 % of the electric fuel costs allowed in th at order. These costs will be subject to the PSCW's annual review of fuel costs completed in the year following the deferral.
Derivative Hedging	As part 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 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 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 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 loss or net gain posi 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 ates as a component of the fuel rules mechanism .
Derivative Netting	All derivative instruments in this table are presented on a gross basis and are calculated prior to the netting of instruments with the same counterparty under a master netting agree ment as well as the netting of collatera l. For financial statement purposes, instruments are netted with the same counterparty under a master netting agreement as well as the netting of collatera l
Recurring Fair Value Measurements	Fair value is defined as the price that would be received to sell an asset or would be paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. The accounting standard clarifies that fair value should be based on the assumptions market participants would use when pricing the asset or liability including ass umptions about risk. The st andard also establishes a three- level fair value hierarchy based upon the observability of the assumptions used and requires the use of observable market data when available. The levels are: Level 1 - Pricing inputs are quoted p rices within active markets for identical assets or liabilities. Level 2 - Pricing inputs are quoted prices within active markets for similar assets or liabilities; quoted prices for identical or similar instruments in markets that are not active; and mod el-derived valuations that are correlated with or otherwise verifiable by observable market data. Level 3 - Pricing inputs are unobservable and reflect management ' s best estimate of what market participants would use in pricing the asset or liability. T he carrying amount of cash , cash equivalents, and outstanding commercial paper approximates fair market value due to the short maturity of those investments and obligations. The estimated fair market value of long-term debt is based on quoted market prices for similar financial instruments . Since long-term debt is not traded in an active market, it is classified as Level 2. I nvestments include exchange-traded investment securities valued using quoted prices on active exchanges and are therefore classified as Level 1. Derivatives include exchange-traded derivative c ontracts, over-the-counter transactions, a purchased power agreement, and FTRs. Most exchange-traded derivative contracts are valued based on unadjusted quoted prices in active markets and are therefore class ified as Level 1. A small number of exchange-traded derivative contracts are valued using quoted market pricing in markets with insufficient volumes and are therefore considered unobservable and classified as Level 3. Transactions done with an over-the-cou nter party are on inactive markets and are therefore classified as Level 3. These transactions are valued based on quoted prices from markets with similar exchange - traded transactions. FTRs are priced based upon monthly auction results for identical or sim ilar instruments in a closed market with limited data available and are therefore classified as Level 3. The purchased power agreement (see Footnote 11 ) was valued using an internally-developed pricing model and therefore is classified as Level 3. The model projects future market energy prices and compares those prices to the projected power costs to be incurred under the contract. Inputs to the model require significant management judgmen t and estimation. Future energy prices are based on a forward power pricing curve using exchange-traded contracts in the electric futures market . A basis adjustment is applied to the market energy price to reflect the price differential between the market price delivery point and the counterpa rty delivery point. The historical relationship between the delivery points is reviewed and a discount (below 100%) or premium (above 100%) is derived. This comparison is done for both peak times when demand is high and off- peak times when demand is low. I f the basis adjustment is lowered, the fair value measurement will decrease, and if the basis adjustment is increased, the fair value measurement will increase. The projected power costs anticipated to be incurred under the purchased power agreement are d etermined using many factors, including historical generating costs, future prices, and expected fuel mix of the counterparty. An increase in the projected fuel costs would result in a decrease in the fair value measurement of the purchased power agreement . A significant input that MGE estimates is the counterparty ' s fuel mix in determining the projected power cost. MGE also considers the assumptions that market participants would use in valuing the asset or liability. This consideration includes assumption s about market risk such as liquidity, volatility , and contract duration. The fair value model uses a discount rate that incorporates discounting, credit, and model risks. The following table presents the significant unobservable inputs used in the pricin g model. Model Input Significant Unobservable Inputs March 31, 2019 December 31, 2018 Basis adjustment: On peak 92.1 % 92.1 % Off peak 92.5 % 92.8 % Counterparty fuel mix: Internal generation 40% - 60% 50% - 75% Purchased power 60% - 40% 50% - 25% The deferred compensation plan allows participants to defer certain cash compensation into a notional investment account. These amounts are included within other deferred liabilities in the consolidated balance sheets . The notional investments earn interest based upon the semiannual rate of U.S. Treasury Bills having a 26 -w eek maturity increased by 1 % compounded monthly with a minimum annual rate of 7 %, compounded monthly. The notional investments are based upon observable market data , however, since the deferred compensation obligations themselves are not exchanged in an active market, they are classified as Level 2 .
Asset Retirement Obligations	A liability for the fair value of an asset retirement obligation (ARO) is recognized in the period in which it is incurred if it can be reasonably estimated. The offsetting associated asset retirement costs are capitalized as a long-lived asset and depreciated over the asset's useful life.
Revenue Recognition	Performance Obligations A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account. A contract's transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. The majority of MGE Energy's and MGE's contracts have a single performance obligation. Retail Revenue (Residential, Commercial, Industrial, and Other Retail/Municipal) Retail reve nue of electric and gas utility service represent MGE's core business activities. Tariffs are approved by the PSCW through a rate order and provide MGE's customers with the standard terms and conditions, including pricing terms. The performance obligation to deliver electricity or gas is satisfied over time as the customer simultaneously receives and consumes the commodities provided by MGE. MGE recognizes revenues as the commodity is delivered to customers. Meters are read on a systematic basis throughout the month based on established meter-reading schedules and the customer is subsequently billed for their services. At the end of the month, MGE accrues an estimate for the unbilled amount of commodities delivered to customers. The unbilled revenue estimate is based on daily system demand volumes, weather factors, estimated line losses, estimated customer usage by class, and applicable customer rates. Utility Cost Recovery Mechanisms MGE's tariff rates include a provision for fuel cost recovery. The PSCW a llows Wisconsin utilities to defer electric fuel-related costs, less excess revenues, that fall outside a symmetrical cost tolerance band. Any over/under recovery of the actual costs in a given year is determined in the following year and is then reflected in future billings to electric retail customers. Over-collection of fuel-related costs that are outside the approved range will be recognized as a reduction of revenue. Under-collection of these costs will be recognized in "Purchased power" expense in the consolidated statements of income. The cumulative effects of these deferred amounts will be recorded in "Regulatory assets" or "Regulatory liabilities" on the consolidated balance sheets until they are reflected in future billings to customers. See Footn ote 10.b. for further information. MGE received a PSCW order in January 2018 to defer the over-collection of income tax expense collected in customer rates during 2018 as a result of the Tax Cuts and Jobs Act (the Tax Act) reduction in the income tax rate to 21 percent. MGE has other cost recovery mechanisms. For example, any over-collection of the difference between actual costs incurred and the amount of costs collected from customers is recorded as a reduction of revenue in the period incurred. Sales to the Market Sales to the market include energy charges, capacity or demand charges, and ancillary charges represented by wholesale sales of electricity made to third parties who are not ultimate users of the electricity. Most of these sales are spot market transactions on the markets operated by MISO. Each transaction is considered a performance obligation and revenue is recognized in the period in which energy charges, capacity or demand charges, and ancillary services are so ld into MISO. MGE reports, on a net basis, transactions on the MISO markets in which it buys and sells power within the same hour to meet electric energy delivery requirements. Transportation of Gas MGE has contracts under which MGE provides gas transpor tation services to customers who have elected to purchase gas from a third party and have the gas delivered via pipelines within MGE's service territory. Revenue is recognized as service is rendered or gas is delivered to customers. Tariffs are approved by the PSCW through a rate order and provide gas transportation customers with the standard terms and conditions, including pricing terms.

Summary of Significant Accoun_2

Summary of Significant Accounting Principles (Tables)	3 Months Ended
	Mar. 31, 2019
Cash, Cash Equivalents, And Restricted Cash [Abstract]
Cash, Cash Equivalents, and Restricted Cash	The following table presents the components of total cash, cash equivalents and restricted cash on the consolidated balance sheets. MGE Energy MGE March 31, December 31, March 31, December 31, (In thousands) 2019 2018 2019 2018 Cash and cash equivalents $ 82,402 $ 83,102 $ 9,624 $ 4,843 Restricted cash 444 634 444 634 Receivable - margin account 1,570 1,193 1,570 1,193 Cash, cash equivalents, and restricted cash $ 84,416 $ 84,929 $ 11,638 $ 6,670

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Lease Cost	The following table shows lease expense for three months ended March 31, 2019 : (In thousands) Income Statement Location Finance lease expense: Amortization of leased assets $ 432 Depreciation and amortization Interest on lease liabilities 199 Interest expense, net Operating lease expense 27 Other operations and maintenance Total lease expense $ 658
Lease Balance Sheet	The following table shows the lease assets and liabilities on the consolidated balance sheet as of March 31, 2019 : (In thousands) Balance Sheet Location Lease assets: Finance lease assets $ 16,976 Finance lease assets Operating lease assets 121 Other deferred assets and other Total lease assets $ 17,097 Lease liabilities: Finance lease liabilities - current $ 1,049 Other current liabilities Finance lease liabilities - long-term 17,666 Finance lease liabilities Operating lease liabilities - current 72 Other current liabilities Operating lease liabilities - long-term 85 Other deferred liabilities and other Total lease liabilities $ 18,872
Other Financial Information	The following table shows other financial lease information for the three months ended March 31, 2019 : (In thousands) Cash paid for amounts included in the measurement of lease liabilities: Finance leases - Financing cash flows $ 494 Finance leases - Operating cash flows 199 Operating leases - Operating cash flows 34 Lease assets obtained in exchange for lease liabilities: Finance leases 11,919 Operating leases -
Weighted Average And Discount Rate	The following table shows the weighted average remaining lease terms and discount rates as of March 31, 2019 : Weighted-average remaining lease terms (in years): Finance leases 37 Operating leases 7 Weighted-average discount rates: Finance leases 4.36 % Operating leases 4.21 %
Lessee Operating Lease Liability Maturity	The following table shows maturities of lease liabilities as of March 31, 2019 : (In thousands) Finance Operating 2019 $ 1,193 $ 58 2020 1,600 69 2021 1,385 2 2022 1,266 2 2023 1,217 2 Thereafter 41,316 52 Subtotal 47,977 185 Less: Present value discount (29,262) (28) Lease liability $ 18,715 $ 157
Lessee Finance Lease Liability Maturity	The following table shows maturities of lease liabilities as of March 31, 2019 : (In thousands) Finance Operating 2019 $ 1,193 $ 58 2020 1,600 69 2021 1,385 2 2022 1,266 2 2023 1,217 2 Thereafter 41,316 52 Subtotal 47,977 185 Less: Present value discount (29,262) (28) Lease liability $ 18,715 $ 157
Operating Leases, Future Minimum Rental Payments	Future minimum rental payments as of December 31, 2018, under agreements classified as operating leases with noncancelable terms in excess of one year are as follows: (In thousands) 2019 2020 2021 2022 2023 Thereafter Minimum lease payments $ 1,646 $ 1,371 $ 1,095 $ 989 $ 975 $ 22,707

Investment in ATC and ATC Hol_2

Investment in ATC and ATC Holdco (Tables)	3 Months Ended
	Mar. 31, 2019
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments Financial Data	MGE Transco and MGEE Transco have accounted for their investment s in ATC and ATC Holdco, re spectively, under the equity method of accounting. Equity earnings from investments are recorded as " Other income " on the consolidated statements of income of MGE Energy. MGE Transco recorded the follo wing : Three Months Ended March 31, (In thousands) 2019 2018 Equity earnings from investment in ATC $ 2,218 $ 2,451 Dividends from ATC (a) 2,012 - Capital contributions to ATC 178 710 (a) MGE Transco recorded a $2.3 million dividend receivable from ATC as of December 31, 2017. A cash dividend was received in January of the proceeding year. ATC ' s summarized financial data is as follows: Three Months Ended March 31, (In thousands) 2019 2018 Operating revenues $ 177,715 $ 165,429 Operating expenses (90,387) (84,893) Other income, net 260 111 Interest expense, net (29,118) (27,762) Earnings before members' income taxes $ 58,470 $ 52,885

Taxes (Tables)

Taxes (Tables)	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Effective Tax Rate Reconciliation	The consolidated income tax provision differs from the amount computed by applying the statutory federal income tax rate to income before income taxes, as follows: MGE Energy MGE Three Months Ended March 31, 2019 2018 2019 2018 Statutory federal income tax rate 21.0 % 21.0 % 21.0 % 21.0 % State income taxes, net of federal benefit 6.3 % 6.4 % 6.2 % 6.0 % Amortized investment tax credits (0.1) % (0.1) % (0.1) % (0.1) % Credit for electricity from wind energy (a) (5.9) % (0.5) % (6.5) % (0.5) % AFUDC equity, net (0.2) % (0.4) % (0.2) % (0.4) % Amortization of utility excess deferred tax - tax reform (b) (2.4) % (1.8) % (2.6) % (2.0) % Other, net, individually insignificant 0.5 % (0.4) % 0.5 % (0.6) % Effective income tax rate 19.2 % 24.2 % 18.3 % 23.4 % (a) Saratoga Wind Farm became operational in February 2019. (b) Included are impacts of the Tax Cuts and Jobs Act for the regulated utility for excess deferred taxes recognized using a normalization method of accounting. For the three months ended March 31, 201 9 and 201 8 , MGE recognized $ 0.6 million and $ 0.5 million, respectively. The amount and timing of the cash impacts will depend on the period over which certain income tax benefits are provided t o customers, determined by the PSCW.

Pension and Other Postretirem_2

Pension and Other Postretirement Plans (Tables)	3 Months Ended
	Mar. 31, 2019
Compensation and Retirement Disclosure [Abstract]
Schedule of Net Periodic Benefit Costs	The following table presents the components of net periodic benefit costs recognized . Three Months Ended March 31, (In thousands) 2019 2018 Pension Benefits Components of net periodic benefit cost: Service cost $ 1,141 $ 1,457 Interest cost 3,452 3,208 Expected return on assets (5,547) (6,568) Amortization of: Prior service credit (28) (11) Actuarial loss 1,729 1,298 Net periodic benefit cost (credit) $ 747 $ (616) Postretirement Benefits Components of net periodic benefit cost: Service cost $ 219 $ 332 Interest cost 577 658 Expected return on assets (681) (802) Amortization of: Transition obligation 1 1 Prior service credit (667) (667) Actuarial loss 106 128 Net periodic benefit (credit) cost $ (445) $ (350)

Derivative and Hedging Instru_2

Derivative and Hedging Instruments (Tables)	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Notional Volume of Open Derivatives	The gross notional volume of open derivatives is as follows: March 31, 2019 December 31, 2018 Commodity derivative contracts 440,440 MWh 386,440 MWh Commodity derivative contracts 2,871,760 Dth 5,260,000 Dth FTRs 844 MW 2,252 MW PPA 1,900 MW 2,050 MW
Fair Value of Derivative Instruments on the Balance Sheet	The following table summarizes the fai r value of the derivative instruments on the consolidated balance sheet s . All derivative instruments in this table are presented on a gross basis and are calculated prior to the netting of instruments with the same counterparty under a master netting agree ment as well as the netting of collatera l. For financial statement purposes, instruments are netted with the same counterparty under a master netting agreement as well as the netting of collatera l . As of March 31, 2019 , and December 31, 2018 , the rec eivable margin account balance of $ 1.6 million and $ 1.2 million, respectively, is shown net of any collateral posted against derivative positions. Derivative Derivative (In thousands) Assets Liabilities Balance Sheet Location March 31, 2019 Commodity derivative contracts $ 546 $ 114 Other current assets Commodity derivative contracts 129 98 Other deferred charges FTRs 124 - Other current assets PPA N/A 8,730 Derivative liability (current) PPA N/A 22,880 Derivative liability (long-term) December 31, 2018 Commodity derivative contracts $ 727 $ 270 Other current assets Commodity derivative contracts 74 72 Other deferred charges FTRs 241 - Other current assets PPA N/A 8,550 Derivative liability (current) PPA N/A 23,980 Derivative liability (long-term)
Offsetting Assets	The foll owing tables show the ef fect of netting arrangements for recognized derivative assets and liabilities that are subject to a master netting arr angement or similar arrangement on the consolidated balance sheets. Offsetting of Derivative Assets (In thousands) Gross Amounts Gross Amounts Offset in Balance Sheets Collateral Posted Against Derivative Positions Net Amount Presented in Balance Sheets March 31, 2019 Commodity derivative contracts $ 675 $ (212) $ - $ 463 FTRs 124 - - 124 December 31, 2018 Commodity derivative contracts $ 801 $ (342) $ - $ 459 FTRs 241 - - 241
Offsetting Liabilities	Offsetting of Derivative Liabilities (In thousands) Gross Amounts Gross Amounts Offset in Balance Sheets Collateral Posted Against Derivative Positions Net Amount Presented in Balance Sheets March 31, 2019 Commodity derivative contracts $ 212 $ (212) $ - $ - PPA 31,610 - - 31,610 December 31, 2018 Commodity derivative contracts $ 342 $ (342) $ - $ - PPA 32,530 - - 32,530
Derivative Gains and Losses in Balance Sheet	The following table s summarize the unrealized and realized gains (losses) related to the derivative instruments on the consolidated balance sheet s and the consolidated statements of income . 2019 2018 (In thousands) Current and Long-Term Regulatory Asset Other Current Assets Current and Long-Term Regulatory Asset Other Current Assets Three Months Ended March 31: Balance at January 1, $ 31,830 $ 377 $ 41,958 $ 806 Unrealized (gain) loss (922) - 128 - Realized (loss) gain reclassified to a deferred account (260) 260 (158) 158 Realized gain (loss) reclassified to income statement 375 (378) (687) (645) Balance at March 31, $ 31,023 $ 259 $ 41,241 $ 319
Derivative Gains and Losses in Income Statement	Realized losses (gains) 2019 2018 (In thousands) Fuel for Electric Generation/ Purchased Power Cost of Gas Sold Fuel for Electric Generation/ Purchased Power Cost of Gas Sold Three Months Ended March 31: Commodity derivative contracts $ 270 $ 277 $ 374 $ 615 FTRs (135) - (175) - PPA (409) - 518 -

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Estimated Fair Market Value of Financial Instruments	The estimated fair market value of financial instruments are as follows: March 31, 2019 December 31, 2018 (In thousands) Carrying Amount Fair Value Carrying Amount Fair Value MGE Energy Assets: Cash and cash equivalents $ 82,402 $ 82,402 $ 83,102 $ 83,102 Liabilities: Short-term debt - commercial paper 6,000 6,000 13,000 13,000 Long-term debt (a) 501,303 553,598 502,431 518,811 MGE Assets: Cash and cash equivalents $ 9,624 $ 9,624 $ 4,843 $ 4,843 Liabilities: Short-term debt - commercial paper 6,000 6,000 13,000 13,000 Long-term debt (a) 501,303 553,598 502,431 518,811 (a) Includes long-term debt due within one year. Excludes debt issuance costs and unamortized discount of $4.4 million and $4.5 million as of March 31, 2019, and December 31, 2018, respectively.
Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following table presents the balances of assets and liabilities measured at fair value on a recurr ing basis . Fair Value as of March 31, 2019 (In thousands) Total Level 1 Level 2 Level 3 MGE Energy Assets: Derivatives, net $ 799 $ 316 $ - $ 483 Exchange-traded investments 963 963 - - Total Assets $ 1,762 $ 1,279 $ - $ 483 Liabilities: Derivatives, net $ 31,822 $ 56 $ - $ 31,766 Deferred compensation 3,009 - 3,009 - Total Liabilities $ 34,831 $ 56 $ 3,009 $ 31,766 MGE Assets: Derivatives, net $ 799 $ 316 $ - $ 483 Exchange-traded investments 70 70 - - Total Assets $ 869 $ 386 $ - $ 483 Liabilities: Derivatives, net $ 31,822 $ 56 $ - $ 31,766 Deferred compensation 3,009 - 3,009 - Total Liabilities $ 34,831 $ 56 $ 3,009 $ 31,766 Fair Value as of December 31, 2018 (In thousands) Total Level 1 Level 2 Level 3 MGE Energy Assets: Derivatives, net $ 1,042 $ 296 $ - $ 746 Exchange-traded investments 848 848 - - Total Assets $ 1,890 $ 1,144 $ - $ 746 Liabilities: Derivatives, net $ 32,872 $ 124 $ - $ 32,748 Deferred compensation 3,078 - 3,078 - Total Liabilities $ 35,950 $ 124 $ 3,078 $ 32,748 MGE Assets: Derivatives, net $ 1,042 $ 296 $ - $ 746 Exchange-traded investments 43 43 - - Total Assets $ 1,085 $ 339 $ - $ 746 Liabilities: Derivatives, net $ 32,872 $ 124 $ - $ 32,748 Deferred compensation 3,078 - 3,078 - Total Liabilities $ 35,950 $ 124 $ 3,078 $ 32,748
Significant Unobservable Inputs	The following table presents the significant unobservable inputs used in the pricin g model. Model Input Significant Unobservable Inputs March 31, 2019 December 31, 2018 Basis adjustment: On peak 92.1 % 92.1 % Off peak 92.5 % 92.8 % Counterparty fuel mix: Internal generation 40% - 60% 50% - 75% Purchased power 60% - 40% 50% - 25%
Changes in Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following table summarizes the changes in Level 3 commodity derivative assets and liabilities measured at fair value on a recurring b asis . Three Months Ended March 31, (In thousands) 2019 2018 Beginning balance $ (32,002) $ (42,026) Realized and unrealized gains (losses): Included in regulatory assets 719 563 Included in other comprehensive income - - Included in earnings (644) (542) Included in current assets 173 (173) Purchases 5,765 5,834 Sales - - Issuances - - Settlements (5,294) (5,119) Transfers in and/or out of Level 3 - - Balance as of March 31, $ (31,283) $ (41,463) Total gains (losses) included in earnings attributed to the change in unrealized gains (losses) related to assets and liabilities held at March 31, (b) $ - $ - (b ) MGE's exchange-traded derivative contracts, over-the-counter party transactions, purchased power agreement, and FTRs are subject to regulatory deferral. These derivatives are therefore marked to fair value and are offset in the financial statements with a corresponding regulatory asset or liability.
Gains and Losses Included in Income for Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following table presents total realized and unrealized gains ( losses ) inc luded in income for Level 3 assets and liabilities measured at fair value on a recurring basis (b ) . Three Months Ended March 31, (In thousands) 2019 2018 Purchased power expense $ (556) $ (723) Cost of gas sold expense (88) 181 Total $ (644) $ (542) (b ) MGE's exchange-traded derivative contracts, over-the-counter party transactions, purchased power agreement, and FTRs are subject to regulatory deferral. These derivatives are therefore marked to fair value and are offset in the financial statements with a corresponding regulatory asset or liability.

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2019
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	Revenues disaggregated by revenue source were as follows: Three Months Ended (In thousands) March 31, Electric revenues 2019 2018 Residential $ 34,581 $ 33,259 Commercial 49,253 47,452 Industrial 2,931 2,895 Other-retail/municipal 8,239 8,287 Total retail 95,004 91,893 Sales to the market 1,961 2,034 Other revenues 451 464 Total electric revenues 97,416 94,391 Gas revenues Residential 40,317 36,551 Commercial/Industrial 28,125 24,952 Total retail 68,442 61,503 Gas transportation 1,536 1,135 Other revenues 122 127 Total gas revenues 70,100 62,765 Nonregulated energy revenues 53 476 Total Operating Revenue $ 167,569 $ 157,632

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Segment Information	The following table s show segment information for MGE Energy ' s operations for the indicated periods : (In thousands) MGE Energy Electric Gas Nonregulated Energy Transmission Investment All Others Consolidation/ Elimination Entries Consolidated Total Three Months Ended March 31, 2019 Operating revenues $ 97,416 $ 70,100 $ 53 $ - $ - $ - $ 167,569 Interdepartmental revenues 199 4,962 9,973 - - (15,134) - Total operating revenues 97,615 75,062 10,026 - - (15,134) 167,569 Depreciation and amortization (12,509) (2,760) (1,870) - - - (17,139) Other operating expenses (73,294) (61,438) (48) - (272) 15,134 (119,918) Operating income (loss) 11,812 10,864 8,108 - (272) - 30,512 Other income, net 1,653 554 - 2,168 476 - 4,851 Interest (expense) income, net (3,665) (1,040) (1,290) - 348 - (5,647) Income before taxes 9,800 10,378 6,818 2,168 552 - 29,716 Income tax provision (451) (2,618) (1,857) (591) (192) - (5,709) Net income $ 9,349 $ 7,760 $ 4,961 $ 1,577 $ 360 $ - $ 24,007 Three Months Ended March 31, 2018 Operating revenues $ 94,391 $ 62,765 $ 476 $ - $ - $ - $ 157,632 Interdepartmental revenues 31 4,347 9,820 - - (14,198) - Total operating revenues 94,422 67,112 10,296 - - (14,198) 157,632 Depreciation and amortization (9,378) (2,395) (1,850) - - - (13,623) Other operating expenses (76,575) (55,195) (43) (3) (203) 14,198 (117,821) Operating income (loss) 8,469 9,522 8,403 (3) (203) - 26,188 Other income, net 1,730 766 - 2,372 51 - 4,919 Interest (expense) income, net (2,867) (839) (1,348) - 315 - (4,739) Income before taxes 7,332 9,449 7,055 2,369 163 - 26,368 Income tax provision (1,200) (2,458) (1,922) (648) (139) - (6,367) Net income $ 6,132 $ 6,991 $ 5,133 $ 1,721 $ 24 $ - $ 20,001 The following table s show segment information for MGE ' s operations for the indicated periods : (In thousands) MGE Electric Gas Nonregulated Energy Consolidation/ Elimination Entries Consolidated Total Three Months Ended March 31, 2019 Operating revenues $ 97,416 $ 70,100 $ 53 $ - $ 167,569 Interdepartmental revenues 199 4,962 9,973 (15,134) - Total operating revenues 97,615 75,062 10,026 (15,134) 167,569 Depreciation and amortization (12,509) (2,760) (1,870) - (17,139) Other operating expenses (73,294) (61,438) (48) 15,134 (119,646) Operating income 11,812 10,864 8,108 - 30,784 Other income, net 1,653 554 - - 2,207 Interest expense, net (3,665) (1,040) (1,290) - (5,995) Income before taxes 9,800 10,378 6,818 - 26,996 Income tax provision (451) (2,618) (1,857) - (4,926) Net income 9,349 7,760 4,961 - 22,070 Less: Net income attributable to noncontrolling interest, net of tax - - - (5,490) (5,490) Net income attributable to MGE $ 9,349 $ 7,760 $ 4,961 $ (5,490) $ 16,580 Three Months Ended March 31, 2018 Operating revenues $ 94,391 $ 62,765 $ 476 $ - $ 157,632 Interdepartmental revenues 31 4,347 9,820 (14,198) - Total operating revenues 94,422 67,112 10,296 (14,198) 157,632 Depreciation and amortization (9,378) (2,395) (1,850) - (13,623) Other operating expenses (76,575) (55,195) (43) 14,198 (117,615) Operating income 8,469 9,522 8,403 - 26,394 Other income, net 1,731 766 - - 2,497 Interest expense, net (2,867) (839) (1,348) - (5,054) Income before taxes 7,333 9,449 7,055 - 23,837 Income tax provision (1,201) (2,458) (1,922) - (5,581) Net income 6,132 6,991 5,133 - 18,256 Less: Net income attributable to noncontrolling interest, net of tax - - - (5,806) (5,806) Net income attributable to MGE $ 6,132 $ 6,991 $ 5,133 $ (5,806) $ 12,450 The following table shows segment information for assets and capital expenditures: Utility Consolidated (In thousands) MGE Energy Electric Gas Nonregulated Energy Transmission Investment All Others Consolidation/ Elimination Entries Total Assets: March 31, 2019 $ 1,223,815 $ 368,043 $ 262,979 $ 66,720 $ 461,159 $ (379,150) $ 2,003,566 December 31, 2018 1,193,083 377,005 265,301 66,366 465,661 (378,798) 1,988,618 Capital Expenditures: Three months ended March 31, 2019 $ 24,095 $ 7,145 $ 693 $ - $ - $ - $ 31,933 Year ended Dec. 31, 2018 176,399 30,497 5,301 - - - 212,197 Utility Consolidated (In thousands) MGE Electric Gas Nonregulated Energy Elimination Entries Total Assets: March 31, 2019 $ 1,223,815 $ 368,043 $ 262,929 $ (990) $ 1,853,797 December 31, 2018 1,193,083 377,005 265,251 (448) 1,834,891 Capital Expenditures: Three months ended March 31, 2019 $ 24,095 $ 7,145 $ 693 $ - $ 31,933 Year ended Dec. 31, 2018 176,399 30,497 5,301 - 212,197

Summary of Significant Accoun_3

Summary of Significant Accounting Principles (Details-1) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents	$ 82,402	$ 83,102
Restricted cash	444	634
Receivable - margin account	1,570	1,193
Cash, cash equivalents, and restricted cash	84,416	84,929	$ 106,245	$ 112,094
MGE [Member]
Cash Cash Equivalents And Restricted Cash [Line Items]
Cash and cash equivalents	9,624	4,843
Restricted cash	444	634
Receivable - margin account	1,570	1,193
Cash, cash equivalents, and restricted cash	$ 11,638	$ 6,670	$ 9,240	$ 10,093

Leases (Details-1)

Leases (Details-1) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Lease Cost [Abstract]
Amortization of leased assets, Depreciation and amortization	$ 432
Interest on lease liabilities, Interest expense, net	199
Operating lease expense, Other operations and maintenance	27
Total lease expense	$ 658

Leases (Details-2)

Leases (Details-2) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Lessee Disclosure [Abstract]
Finance lease assets, net, Finance lease assets	$ 16,976	$ 2,181
Operating lease assets, Other deferred assets and other	121
Total lease assets	17,097
Finance lease liabilities - current, Other current liabilities	1,049
Finance lease liabilities - long term, Finance lease liabilities	17,666	$ 1,771
Operating lease liabilities - current, Other current liabilities	72
Operating lease liabilities - long term, Other deferred liabilities and other	85
Total lease liabilities	$ 18,872

Leases (Details-3)

Leases (Details-3) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Lessee Disclosure [Abstract]
Finance leases - Financing cash flows	$ 494
Finance leases - Operating cash flows	199
Operating leases - operating cash flows	34
Lease assets obtained in exchange for lease liabilities - finance leases	11,919
Lease assets obtained in exchange for lease liabilities - operating leases	$ 0

Leases (Details-4)

Leases (Details-4)	Mar. 31, 2019
Lessee Disclosure [Abstract]
Weighted average remaining lease term (years) finance leases	37 years
Weighted average remaining lease term (years) operating leases	7 years
Weighted average disocunt rate operating leases	4.36%
Weighted average disocunt rate operating leases	4.21%

Leases (Details-5)

Leases (Details-5) $ in Thousands	Mar. 31, 2019USD ($)
Finance Lease Liabilities Payments Due [Abstract]
2019	$ 1,193
2020	1,600
2021	1,385
2022	1,266
2023	1,217
Thereafter	41,316
Undiscounted finance lease liability	47,977
Less: Present value discount	(29,262)
Finance lease liability	18,715
Operating Lease Liabilities Payments Due [Abstract]
2019	58
2020	69
2021	2
2022	2
2023	2
Thereafter	52
Undiscounted operating lease liability	185
Less: Present value discount	(28)
Operating lease liability	$ 157

Leases (Details-6)

Leases (Details-6) $ in Thousands	Dec. 31, 2018USD ($)
Operating Leases Future Minimum Payments Due [Abstract]
Minimum lease payments, 2019	$ 1,646
Minimum lease payments, 2020	1,371
Minimum lease payments, 2021	1,095
Minimum lease payments, 2022	989
Minimum lease payments, 2023	975
Minimum lease payments, Thereafter	$ 22,707

Investment in ATC and ATC Hol_3

Investment in ATC and ATC Holdco (Details-1) - USD ($) $ in Thousands	Apr. 30, 2019	Mar. 31, 2019	Mar. 31, 2018		Dec. 31, 2017
Schedule Of Equity Method Investments [Line Items]
Equity earnings from investment in ATC		$ 2,218	$ 2,451
Dividends from ATC		2,012	2,348
Capital contributions to investments		740	1,877
MGE Transco [Member] | ATC [Member]
Schedule Of Equity Method Investments [Line Items]
Equity earnings from investment in ATC		2,218	2,451
Dividends from ATC		2,012	0	[1]
Capital contributions to investments		$ 178	$ 710
Dividend receivable from ATC					$ 2,300
MGE Transco [Member] | ATC [Member] | Subsequent Event [Member]
Schedule Of Equity Method Investments [Line Items]
Capital contributions to investments	$ 1,100
[1]	MGE Transco recorded a $2.3 million dividend receivable from ATC as of December 31, 2017. A cash dividend was received in January of the proceeding year.

Investment in ATC and ATC Hol_4

Investment in ATC and ATC Holdco (Details-2) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
ATC [Member]
Schedule Of Equity Method Investments [Line Items]
Operating revenues	$ 177,715	$ 165,429
Operating expenses	(90,387)	(84,893)
Other income, net	260	111
Interest expense, net	(29,118)	(27,762)
Earnings before members' income taxes	58,470	52,885
ATC [Member]
Related Party Transaction [Line Items]
Related party expenses	7,600	$ 7,200
Due from related parties	$ 100		$ 100

Taxes (Details)

Taxes (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019		Mar. 31, 2018
Reconciliation of tax provision to statutory federal income tax rate [Abstract]
Statutory federal income tax rate		21.00%		21.00%
State income taxes, net of federal benefit		6.30%		6.40%
Amortized investment tax credits		(0.10%)		(0.10%)
Credit for electricity from wind energy		(5.90%)	[1]	(0.50%)
AFUDC equity, net		(0.20%)		(0.40%)
Amortization of utility excess deferred tax - tax reform	[2]	(2.40%)		(1.80%)
Other, net, individually significant		0.50%		(0.40%)
Effective income tax rate		19.20%		24.20%
Excess Deferred Taxes, Tax Cuts And Jobs Act [Member]
Effects Of The Tax Cuts And Jobs Act [Abstract]
Excess deferred tax - Income statement effect		$ 0.6		$ 0.5
MGE [Member]
Reconciliation of tax provision to statutory federal income tax rate [Abstract]
Statutory federal income tax rate		21.00%		21.00%
State income taxes, net of federal benefit		6.20%		6.00%
Amortized investment tax credits		(0.10%)		(0.10%)
Credit for electricity from wind energy		(6.50%)	[1]	(0.50%)
AFUDC equity, net		(0.20%)		(0.40%)
Amortization of utility excess deferred tax - tax reform	[2]	(2.60%)		(2.00%)
Other, net, individually significant		0.50%		(0.60%)
Effective income tax rate		18.30%		23.40%
[1]	Saratoga Wind Farm became operational in February 2019.
[2]	Included are impacts of the Tax Cuts and Jobs Act for the regulated utility for excess deferred taxes recognized using a normalization method of accounting. For the three months ended March 31, 201 9 and 201 8 , MGE recognized $ 0.6 million and $ 0.5 million, respectively. The amount and timing of the cash impacts will depend on the period over which certain income tax benefits are provided t o customers, determined by the PSCW.

Pension and Other Postretirem_3

Pension and Other Postretirement Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Pension Benefits [Member]
Components of net periodic benefit cost:
Service cost	$ 1,141	$ 1,457
Interest cost	3,452	3,208
Expected return on assets	(5,547)	(6,568)
Amortization of:
Prior service credit	(28)	(11)
Actuarial loss	1,729	1,298
Net periodic benefit (credit) cost	747	(616)
Postretirement Benefits [Member]
Components of net periodic benefit cost:
Service cost	219	332
Interest cost	577	658
Expected return on assets	(681)	(802)
Amortization of:
Transition obligation	1	1
Prior service credit	(667)	(667)
Actuarial loss	106	128
Net periodic benefit (credit) cost	$ (445)	$ (350)

Equity and Financing Arrangem_2

Equity and Financing Arrangements (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Common Stock [Abstract]
Common stock issued during period	0	0
Dilutive Shares Calculation [Abstract]
Dilutive securities	$ 0

Share Based Compensation (Detai

Share Based Compensation (Details) - Performance Units [Member] - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Jan. 31, 2019	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense		$ 1.2	$ 0.2
Cash payments distributed related to awards previously granted and now payable	$ 1.5
Awards forfeited during period, value		$ 0	$ 0
Awards forfeited during period, units		0	0
Outstanding awards vested during period		$ 5.3
Director Incentive Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted during period (in units)		5,175
Award vesting period		3 years
Performance Unit Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards granted during period (in units)		17,022
Award vesting period		5 years

Commitments and Contingencies (

Commitments and Contingencies (Details-1)	Mar. 31, 2019MW
Minimum [Member]
EPA Greenhouse Gas Reduction Guidelines
Standard of Performance Plan For EGUs Over Threshold	25

Rate Matters (Details)

Rate Matters (Details) - PSCW [Member] - MGE [Member] - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2018
Rate Proceedings [Abstract]
Authorized return on equity, percentage	9.80%	9.80%
Approved equity capital structure, percentage	56.60%	56.10%
Fuel Rules [Abstract]
Fuel rules, bandwidth	2.00%
Fuel rules, electric fuel deferred costs upper threshold	102.00%
Fuel rules, electric fuel deferred costs lower threshold	98.00%
Deferred fuel rules monitored costs	$ 0		$ 9.5
Public Utilities Fuel Surcharge Amount			$ 0.5
Public Utilities Fuel Surcharge Percentage			0.13%
Electric Rate Proceeding [Member]
Rate Proceedings [Abstract]
Authorized rate increase (decrease), percentage	(2.24%)	0.00%
Authorized rate increase (decrease), amount	$ (9.2)
Gas Rate Proceeding [Member]
Rate Proceedings [Abstract]
Authorized rate increase (decrease), percentage	1.06%	1.46%
Authorized rate increase (decrease), amount	$ 1.7	$ 2.4

Derivative and Hedging Instru_3

Derivative and Hedging Instruments (Details-1) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019USD ($)DthMWhMW	Dec. 31, 2018USD ($)DthMWhMW	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Derivative fair values [Abstract]
Receivable, margin account balance, net of collateral posted against derivative positions	$ 1,570	$ 1,193
Other Current Assets [Member]
Derivative fair values [Abstract]
Derivative fair value, net	259	377	$ 319	$ 806
Commodity Contracts And Financial Transimission Rights [Member]
Derivative fair values [Abstract]
Derivative fair value, net	$ 600	$ 700
Commodity Derivative Contracts [Member]
Gross Notional Volume of Open Derivatives
Notional amount, energy measure (in MWh) | MWh	440,440	386,440
Notional amount, decatherm measure (in Dth) | Dth	2,871,760	5,260,000
Derivative fair values [Abstract]
Asset Derivatives, fair value, gross basis	$ 675	$ 801
Liability Derivatives, fair value, gross basis	212	342
Commodity Derivative Contracts [Member] | Other Current Assets [Member]
Derivative fair values [Abstract]
Asset Derivatives, fair value, gross basis	546	727
Liability Derivatives, fair value, gross basis	114	270
Commodity Derivative Contracts [Member] | Other Deferred Charges [Member]
Derivative fair values [Abstract]
Asset Derivatives, fair value, gross basis	129	74
Liability Derivatives, fair value, gross basis	$ 98	$ 72
Energy Related Commodity Contract [Member] | Cash Flow Hedging [Member]
Derivatives Fair Value [Line Items]
Maximum term of derivative hedging contract	4 years
Financial Transmission Rights [Member]
Gross Notional Volume of Open Derivatives
Notional amount, power measure (in MW) | MW	844	2,252
Derivative fair values [Abstract]
Asset Derivatives, fair value, gross basis	$ 124	$ 241
Financial Transmission Rights [Member] | Other Current Assets [Member]
Derivative fair values [Abstract]
Asset Derivatives, fair value, gross basis	124	241
Liability Derivatives, fair value, gross basis	$ 0	$ 0
PPA [Member]
Gross Notional Volume of Open Derivatives
Notional amount, power measure (in MW) | MW	1,900	2,050
Derivative fair values [Abstract]
Derivative fair value, net	$ (31,600)	$ (32,500)
Liability Derivatives, fair value, gross basis	31,610	32,530
PPA [Member] | Derivative Liability (Current) [Member]
Derivative fair values [Abstract]
Liability Derivatives, fair value, gross basis	8,730	8,550
PPA [Member] | Derivative Liability (Long-term) [Member]
Derivative fair values [Abstract]
Liability Derivatives, fair value, gross basis	$ 22,880	$ 23,980

Derivative and Hedging Instru_4

Derivative and Hedging Instruments (Details-2) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Commodity Derivative Contracts [Member]
Offsetting Assets [Line Items]
Gross amounts	$ 675	$ 801
Gross amounts offset in balance sheet	(212)	(342)
Collateral posted against derivative positions	0	0
Net amount presented in balance sheet	463	459
Financial Transmission Rights [Member]
Offsetting Assets [Line Items]
Gross amounts	124	241
Gross amounts offset in balance sheet	0	0
Collateral posted against derivative positions	0	0
Net amount presented in balance sheet	$ 124	$ 241

Derivative and Hedging Instru_5

Derivative and Hedging Instruments (Details-3) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Commodity Derivative Contracts [Member]
Offsetting Liabilities [Line Items]
Gross amounts	$ 212	$ 342
Gross amounts offset in balance sheet	(212)	(342)
Collateral posted against derivative positions	0	0
Net amount presented in balance sheet	0	0
Purchased Power Agreement [Member]
Offsetting Liabilities [Line Items]
Gross amounts	31,610	32,530
Gross amounts offset in balance sheet	0	0
Collateral posted against derivative positions	0	0
Net amount presented in balance sheet	$ 31,610	$ 32,530

Derivative and Hedging Instru_6

Derivative and Hedging Instruments (Details-4) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Current and Long-Term Regulatory Asset [Member]
Change In Derivative Fair Value [Roll Forward]
Beginning balance,	$ 31,830	$ 41,958
Unrealized loss (gain)	(922)	128
Realized (loss) gain reclassified to a deferred account	(260)	(158)
Realized gain (loss) reclassified to income statement	375	(687)
Ending balance,	31,023	41,241
Other Current Assets [Member]
Change In Derivative Fair Value [Roll Forward]
Beginning balance,	377	806
Unrealized loss (gain)	0	0
Realized (loss) gain reclassified to a deferred account	260	158
Realized gain (loss) reclassified to income statement	(378)	(645)
Ending balance,	$ 259	$ 319

Derivative and Hedging Instru_7

Derivative and Hedging Instruments (Details-5) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)counterparty	Mar. 31, 2018USD ($)	Dec. 31, 2018USD ($)
Counterparties in net liability position or default [Abstract]
Derivative, net liability position of counterparties	$ 0		$ 0
Number of counterparties in default | counterparty	0
Commodity Derivative Contracts [Member] | Fuel For Electric Generation Purchased Power [Member]
Realized losses (gains) on income statement [Line Items]
Realized losses (gains) on income statement	$ 270	$ 374
Commodity Derivative Contracts [Member] | Cost Of Gas Sold Expense [Member]
Realized losses (gains) on income statement [Line Items]
Realized losses (gains) on income statement	277	615
Financial Transmission Rights [Member] | Fuel For Electric Generation Purchased Power [Member]
Realized losses (gains) on income statement [Line Items]
Realized losses (gains) on income statement	(135)	(175)
Financial Transmission Rights [Member] | Cost Of Gas Sold Expense [Member]
Realized losses (gains) on income statement [Line Items]
Realized losses (gains) on income statement	0	0
Purchased Power Agreement [Member]
Derivative collateral required to be posted for PPA [Abstract]
Minimum collateral that may be required to be posted	20,000
Maximum collateral that may be required to be posted	40,000
Collateral posted	0
Purchased Power Agreement [Member] | Fuel For Electric Generation Purchased Power [Member]
Realized losses (gains) on income statement [Line Items]
Realized losses (gains) on income statement	(409)	518
Purchased Power Agreement [Member] | Cost Of Gas Sold Expense [Member]
Realized losses (gains) on income statement [Line Items]
Realized losses (gains) on income statement	$ 0	$ 0

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Details-1) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Fair Value Measurement [Domain]
Liabilities:
Unamortized discount and debt issuance costs, net		$ 4,400	$ 4,500
Carrying Amount [Member]
Assets:
Cash and cash equivalents		82,402	83,102
Liabilities:
Short-term debt - commercial paper		6,000	13,000
Long-term debt	[1]	501,303	502,431
Fair Value [Member]
Assets:
Cash and cash equivalents		82,402	83,102
Liabilities:
Short-term debt - commercial paper		6,000	13,000
Long-term debt	[1]	553,598	518,811
MGE [Member] | Fair Value Measurement [Domain]
Liabilities:
Unamortized discount and debt issuance costs, net		4,400	4,500
MGE [Member] | Carrying Amount [Member]
Assets:
Cash and cash equivalents		9,624	4,843
Liabilities:
Short-term debt - commercial paper		6,000	13,000
Long-term debt	[1]	501,303	502,431
MGE [Member] | Fair Value [Member]
Assets:
Cash and cash equivalents		9,624	4,843
Liabilities:
Short-term debt - commercial paper		6,000	13,000
Long-term debt	[1]	$ 553,598	$ 518,811
[1]	Includes long-term debt due within one year. Excludes debt issuance costs and unamortized discount of $4.4 million and $4.5 million at March 31, 2019 and December 31, 2018, respectively.

Fair Value of Financial Instr_4

Fair Value of Financial Instruments (Details-2) - Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets:
Derivatives	$ 799	$ 1,042
Total Assets	1,762	1,890
Liabilities:
Derivatives	31,822	32,872
Deferred compensation	3,009	3,078
Total liabilities	34,831	35,950
Exchange Traded [Member]
Assets:
Available-for-sale securities	963	848
Level 1 [Member]
Assets:
Derivatives	316	296
Total Assets	1,279	1,144
Liabilities:
Derivatives	56	124
Deferred compensation	0	0
Total liabilities	56	124
Level 1 [Member] | Exchange Traded [Member]
Assets:
Available-for-sale securities	963	848
Level 2 [Member]
Assets:
Derivatives	0	0
Total Assets	0	0
Liabilities:
Derivatives	0	0
Deferred compensation	3,009	3,078
Total liabilities	3,009	3,078
Level 2 [Member] | Exchange Traded [Member]
Assets:
Available-for-sale securities	0	0
Level 3 [Member]
Assets:
Derivatives	483	746
Total Assets	483	746
Liabilities:
Derivatives	31,766	32,748
Deferred compensation	0	0
Total liabilities	31,766	32,748
Level 3 [Member] | Exchange Traded [Member]
Assets:
Available-for-sale securities	0	0
MGE [Member]
Assets:
Derivatives	799	1,042
Total Assets	869	1,085
Liabilities:
Derivatives	31,822	32,872
Deferred compensation	3,009	3,078
Total liabilities	34,831	35,950
MGE [Member] | Exchange Traded [Member]
Assets:
Available-for-sale securities	70	43
MGE [Member] | Level 1 [Member]
Assets:
Derivatives	316	296
Total Assets	386	339
Liabilities:
Derivatives	56	124
Deferred compensation	0	0
Total liabilities	56	124
MGE [Member] | Level 1 [Member] | Exchange Traded [Member]
Assets:
Available-for-sale securities	70	43
MGE [Member] | Level 2 [Member]
Assets:
Derivatives	0	0
Total Assets	0	0
Liabilities:
Derivatives	0	0
Deferred compensation	3,009	3,078
Total liabilities	3,009	3,078
MGE [Member] | Level 2 [Member] | Exchange Traded [Member]
Assets:
Available-for-sale securities	0	0
MGE [Member] | Level 3 [Member]
Assets:
Derivatives	483	746
Total Assets	483	746
Liabilities:
Derivatives	31,766	32,748
Deferred compensation	0	0
Total liabilities	31,766	32,748
MGE [Member] | Level 3 [Member] | Exchange Traded [Member]
Assets:
Available-for-sale securities	$ 0	$ 0

Fair Value of Financial Instr_5

Fair Value of Financial Instruments (Details-3)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Basis adjustment:
Basis adjustment - on peak	92.10%	92.10%
Basis adjustment - off peak	92.50%	92.80%
US Treasury Bill Securities [Member]
Deferred compensation plan [Abstract]
Investment interest calculation, investment maturity period (26 weeks)	182 days
Investment interest calculation, monthly compounding rate	1.00%
Investment interest calculation, minimum annual rate compounded monthly	7.00%
Minimum [Member]
Counterparty fuel mix:
Internal generation	40.00%	50.00%
Purchased power	40.00%	25.00%
Maximum [Member]
Counterparty fuel mix:
Internal generation	60.00%	75.00%
Purchased power	60.00%	50.00%

Fair Value of Financial Instr_6

Fair Value of Financial Instruments (Details-4) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance,		$ (32,002)	$ (42,026)
Realized and unrealized gains (losses):
Included in regulatory assets		719	563
Included in other comprehensive income		0	0
Included in earnings	[1]	(644)	(542)
Included in current assets		173	(173)
Purchases		5,765	5,834
Sales		0	0
Issuances		0	0
Settlements		(5,294)	(5,119)
Transfers in and/or out of level 3		0	0
Ending balance,		(31,283)	(41,463)
Total gains (losses) included in earnings attributed to the change in unrealized gains (losses) related to assets and liabilities	[1]	0	0
Purchased Power Expense [Member]
Realized and unrealized gains (losses):
Included in earnings	[1]	(556)	(723)
Cost Of Gas Sold Expense [Member]
Realized and unrealized gains (losses):
Included in earnings	[1]	$ (88)	$ 181
[1]	MGE's exchange-traded derivative contracts, over-the-counter party transactions, purchased power agreement, and FTRs are subject to regulatory deferral. These derivatives are therefore marked to fair value and are offset in the financial statements with a corresponding regulatory asset or liability.

Asset Retirement Obligation (De

Asset Retirement Obligation (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Saratoga Wind Farm [Member]
Asset Retirement Obligations [Roll Forward]
Saratoga Wind Asset Retirement Obligation	$ 1.5

Revenue (Details-1)

Revenue (Details-1) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Total Operating Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	$ 167,569	$ 157,632
Electric [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	97,416	94,391
Electric [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	34,581	33,259
Electric [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	49,253	47,452
Electric [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	2,931	2,895
Electric [Member] | Other-retail/municipal
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	8,239	8,287
Electric [Member] | Total Retail [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	95,004	91,893
Electric [Member] | Sales To The Market [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	1,961	2,034
Electric [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	451	464
Gas [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	70,100	62,765
Gas [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	40,317	36,551
Gas [Member] | Commercial/Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	28,125	24,952
Gas [Member] | Total Retail [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	68,442	61,503
Gas [Member] | Gas Transportation [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	1,536	1,135
Gas [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	122	127
Non Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	$ 53	$ 476

Segment Information (Details)

Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Operating revenues	$ 167,569	$ 157,632
Depreciation and amortization	(17,139)	(13,623)
Other operating expenses	(119,918)	(117,821)
Operating income (loss)	30,512	26,188
Other income (deductions), net	4,851	4,919
Interest (expense) income, net	(5,647)	(4,739)
Income before income taxes	29,716	26,368
Income tax (provision) benefit	(5,709)	(6,367)
Net Income	24,007	20,001
Segment Reporting Assets And Capital Expenditures [Abstract]
Assets	2,003,566		$ 1,988,618
Capital expenditures	31,933	37,631	212,197
Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	97,416	94,391
Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	70,100	62,765
Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	53	476
Transmission Investment [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0
All Others [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0
Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	167,569	157,632
Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	97,615	94,422
Depreciation and amortization	(12,509)	(9,378)
Other operating expenses	(73,294)	(76,575)
Operating income (loss)	11,812	8,469
Other income (deductions), net	1,653	1,730
Interest (expense) income, net	(3,665)	(2,867)
Income before income taxes	9,800	7,332
Income tax (provision) benefit	(451)	(1,200)
Net Income	9,349	6,132
Segment Reporting Assets And Capital Expenditures [Abstract]
Assets	1,223,815		1,193,083
Capital expenditures	24,095		176,399
Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	75,062	67,112
Depreciation and amortization	(2,760)	(2,395)
Other operating expenses	(61,438)	(55,195)
Operating income (loss)	10,864	9,522
Other income (deductions), net	554	766
Interest (expense) income, net	(1,040)	(839)
Income before income taxes	10,378	9,449
Income tax (provision) benefit	(2,618)	(2,458)
Net Income	7,760	6,991
Segment Reporting Assets And Capital Expenditures [Abstract]
Assets	368,043		377,005
Capital expenditures	7,145		30,497
Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,026	10,296
Depreciation and amortization	(1,870)	(1,850)
Other operating expenses	(48)	(43)
Operating income (loss)	8,108	8,403
Other income (deductions), net	0	0
Interest (expense) income, net	(1,290)	(1,348)
Income before income taxes	6,818	7,055
Income tax (provision) benefit	(1,857)	(1,922)
Net Income	4,961	5,133
Segment Reporting Assets And Capital Expenditures [Abstract]
Assets	262,979		265,301
Capital expenditures	693		5,301
Operating Segments [Member] | Transmission Investment [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0
Depreciation and amortization	0	0
Other operating expenses	0	(3)
Operating income (loss)	0	(3)
Other income (deductions), net	2,168	2,372
Interest (expense) income, net	0	0
Income before income taxes	2,168	2,369
Income tax (provision) benefit	(591)	(648)
Net Income	1,577	1,721
Segment Reporting Assets And Capital Expenditures [Abstract]
Assets	66,720		66,366
Capital expenditures	0		0
Operating Segments [Member] | All Others [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0
Depreciation and amortization	0	0
Other operating expenses	(272)	(203)
Operating income (loss)	(272)	(203)
Other income (deductions), net	476	51
Interest (expense) income, net	348	315
Income before income taxes	552	163
Income tax (provision) benefit	(192)	(139)
Net Income	360	24
Segment Reporting Assets And Capital Expenditures [Abstract]
Assets	461,159		465,661
Capital expenditures	0		0
Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(15,134)	(14,198)
Depreciation and amortization	0	0
Other operating expenses	15,134	14,198
Operating income (loss)	0	0
Other income (deductions), net	0	0
Interest (expense) income, net	0	0
Income before income taxes	0	0
Income tax (provision) benefit	0	0
Net Income	0	0
Segment Reporting Assets And Capital Expenditures [Abstract]
Assets	(379,150)		(378,798)
Capital expenditures	0		0
Consolidation Elimination Entries [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	199	31
Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	4,962	4,347
Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	9,973	9,820
Consolidation Elimination Entries [Member] | Transmission Investment [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0
Consolidation Elimination Entries [Member] | All Others [Member]
Segment Reporting Information [Line Items]
Operating revenues	0	0
MGE [Member]
Segment Reporting Information [Line Items]
Operating revenues	167,569	157,632
Depreciation and amortization	(17,139)	(13,623)
Other operating expenses	(119,646)	117,615
Operating income (loss)	30,784	26,394
Other income (deductions), net	2,207	2,497
Interest (expense) income, net	(5,995)	(5,054)
Income before income taxes	26,996	23,837
Income tax (provision) benefit	(4,926)	(5,581)
Net Income Including Noncontrolling Interest	22,070	18,256
Less Net Income Attributable to Noncontrolling Interest, net of tax	(5,490)	(5,806)
Net Income	16,580	12,450
Segment Reporting Assets And Capital Expenditures [Abstract]
Assets	1,853,797		1,834,891
Capital expenditures	31,933	37,631	212,197
MGE [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	97,416	94,391
MGE [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	70,100	62,765
MGE [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	53	476
MGE [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Operating revenues	167,569	157,632
MGE [Member] | Operating Segments [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	97,615	94,422
Depreciation and amortization	(12,509)	(9,378)
Other operating expenses	(73,294)	(76,575)
Operating income (loss)	11,812	8,469
Other income (deductions), net	1,653	1,731
Interest (expense) income, net	(3,665)	(2,867)
Income before income taxes	9,800	7,333
Income tax (provision) benefit	(451)	(1,201)
Net Income Including Noncontrolling Interest	9,349	6,132
Less Net Income Attributable to Noncontrolling Interest, net of tax	0	0
Net Income	9,349	6,132
Segment Reporting Assets And Capital Expenditures [Abstract]
Assets	1,223,815		1,193,083
Capital expenditures	24,095		176,399
MGE [Member] | Operating Segments [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	75,062	67,112
Depreciation and amortization	(2,760)	(2,395)
Other operating expenses	(61,438)	(55,195)
Operating income (loss)	10,864	9,522
Other income (deductions), net	554	766
Interest (expense) income, net	(1,040)	(839)
Income before income taxes	10,378	9,449
Income tax (provision) benefit	(2,618)	(2,458)
Net Income Including Noncontrolling Interest	7,760	6,991
Less Net Income Attributable to Noncontrolling Interest, net of tax	0	0
Net Income	7,760	6,991
Segment Reporting Assets And Capital Expenditures [Abstract]
Assets	368,043		377,005
Capital expenditures	7,145		30,497
MGE [Member] | Operating Segments [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	10,026	10,296
Depreciation and amortization	(1,870)	(1,850)
Other operating expenses	(48)	(43)
Operating income (loss)	8,108	8,403
Other income (deductions), net	0	0
Interest (expense) income, net	(1,290)	(1,348)
Income before income taxes	6,818	7,055
Income tax (provision) benefit	(1,857)	(1,922)
Net Income Including Noncontrolling Interest	4,961	5,133
Less Net Income Attributable to Noncontrolling Interest, net of tax	0	0
Net Income	4,961	5,133
Segment Reporting Assets And Capital Expenditures [Abstract]
Assets	262,929		265,251
Capital expenditures	693		5,301
MGE [Member] | Consolidation Elimination Entries [Member]
Segment Reporting Information [Line Items]
Operating revenues	(15,134)	(14,198)
Depreciation and amortization	0	0
Other operating expenses	15,134	14,198
Operating income (loss)	0	0
Other income (deductions), net	0	0
Interest (expense) income, net	0	0
Income before income taxes	0	0
Income tax (provision) benefit	0	0
Net Income Including Noncontrolling Interest	0	0
Less Net Income Attributable to Noncontrolling Interest, net of tax	(5,490)	(5,806)
Net Income	(5,490)	(5,806)
Segment Reporting Assets And Capital Expenditures [Abstract]
Assets	(990)		(448)
Capital expenditures	0		$ 0
MGE [Member] | Consolidation Elimination Entries [Member] | Electric [Member]
Segment Reporting Information [Line Items]
Operating revenues	199	31
MGE [Member] | Consolidation Elimination Entries [Member] | Gas [Member]
Segment Reporting Information [Line Items]
Operating revenues	4,962	4,347
MGE [Member] | Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]
Segment Reporting Information [Line Items]
Operating revenues	$ 9,973	$ 9,820