MGE Energy (MGEE) 10-Q 6 Aug 14 2014 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Jun. 30, 2014
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	30-Jun-14
Amendment Flag	'false
Document Fiscal Year Focus	'2014
Document Fiscal Period Focus	'Q2
Current Fiscal Year End Date	'--12-31
Entity Well known Seasoned Issuer	'Yes
Entity Voluntary Filers	'No
Entity Current Reporting Status	'Yes
Entity Filer Category	'Large Accelerated Filer
Entity Common Stock Shares Outstanding	34,668,370
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_St

MGE Energy Inc Consolidated Statements of Income (Unaudited) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Operating Revenues:	'	'	'	'
Regulated electric revenues	$96,697	$96,846	$195,549	$190,340
Regulated gas revenues	31,218	30,042	141,931	102,509
Nonregulated revenues	850	1,400	1,530	2,676
Total Operating Revenues	128,765	128,288	339,010	295,525
Operating Expenses:	'	'	'	'
Fuel for electric generation	11,866	9,810	25,998	20,570
Purchased power	18,921	21,051	37,476	39,256
Cost of gas sold	18,132	16,748	96,640	61,440
Other operations and maintenance	40,208	41,887	80,680	83,536
Depreciation and amortization	10,069	9,530	19,815	19,154
Other general taxes	5,128	4,765	9,989	9,444
Total Operating Expenses	104,324	103,791	270,598	233,400
Operating Income	24,441	24,497	68,412	62,125
Other income, net	3,548	2,711	8,100	6,020
Interest expense, net	-4,868	-4,657	-9,409	-9,332
Income before income taxes	23,121	22,551	67,103	58,813
Income tax provision	-9,034	-8,660	-25,299	-22,338
Net Income (Loss)	$14,087	$13,891	$41,804	$36,475
Earnings Per Share of Common Stock (basic and diluted)	$0.41	$0.40	$1.21	$1.05
Dividends per share of common stock	$0.27	$0.26	$0.54	$0.53
Weighted Average Shares Outstanding (basic and diluted)	34,668	34,668	34,668	34,668

Madison_Gas_and_Electric_Compa

Madison Gas and Electric Company Consolidated Statements of Income (Unaudited) (USD $)	3 Months Ended				6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Operating Revenues:	'		'		'		'
Regulated electric revenues	$96,697		$96,846		$195,549		$190,340
Regulated gas revenues	31,218		30,042		141,931		102,509
Nonregulated revenues	850		1,400		1,530		2,676
Total Operating Revenues	128,765		128,288		339,010		295,525
Operating Expenses:	'		'		'		'
Fuel for electric generation	11,866		9,810		25,998		20,570
Purchased power	18,921		21,051		37,476		39,256
Cost of gas sold	18,132		16,748		96,640		61,440
Other operations and maintenance	40,208		41,887		80,680		83,536
Depreciation and amortization	10,069		9,530		19,815		19,154
Other general taxes	5,128		4,765		9,989		9,444
Income tax provision	9,034		8,660		25,299		22,338
Total Operating Expenses	104,324		103,791		270,598		233,400
Operating Income	24,441		24,497		68,412		62,125
Other Income and Deductions:	'		'		'		'
Equity in earnings in ATC	'		'		4,883		4,705
Total Other Income and Deductions	3,548		2,711		8,100		6,020
Interest Expense:	'		'		'		'
Net Interest Expense	4,868		4,657		9,409		9,332
Net Income (Loss)	14,087		13,891		41,804		36,475
MGE [Member]	'		'		'		'
Operating Revenues:	'		'		'		'
Regulated electric revenues	96,702		96,846		195,560		190,340
Regulated gas revenues	31,223		30,042		141,941		102,509
Nonregulated revenues	850		1,400		1,530		2,676
Total Operating Revenues	128,775		128,288		339,031		295,525
Operating Expenses:	'		'		'		'
Fuel for electric generation	11,868		9,810		26,002		20,570
Purchased power	18,925		21,051		37,483		39,256
Cost of gas sold	18,137		16,748		96,650		61,440
Other operations and maintenance	39,967		41,639		80,284		83,143
Depreciation and amortization	10,058		9,530		19,792		19,154
Other general taxes	5,128		4,765		9,989		9,444
Income tax provision	7,918		7,569		22,842		20,439
Total Operating Expenses	112,001		111,112		293,042		253,446
Operating Income	16,774	[1]	17,176	[1]	45,989	[1]	42,079	[1]
Other Income and Deductions:	'		'		'		'
AFUDC - equity funds	1,101		730		3,051		1,326
Equity in earnings in ATC	2,402		2,309		4,883		4,705
Income tax provision	-1,142		-1,141		-2,406		-1,922
Other income, net	-82		-430		-240		-289
Total Other Income and Deductions	2,279	[1]	1,468	[1]	5,288	[1]	3,820	[1]
Income before interest expense	19,053		18,644		51,277		45,899
Interest Expense:	'		'		'		'
Interest on long-term debt	5,240		4,919		10,489		9,847
Other interest, net	33		1		8		-36
AFUDC - borrowed funds	-363		-241		-1,006		-437
Net Interest Expense	4,910		4,679		9,491		9,374
Net Income Including Noncontrolling Interest	14,143		13,965		41,786		36,525
Less Net Income Attributable to Noncontrolling Interest, net of tax	-6,621		-6,860		-13,131		-13,686
Net Income (Loss)	$7,522		$7,105		$28,655		$22,839
[1]	*Amounts are shown net of the related tax expense, consistent with the presentation on the consolidated MGE Income Statement.

MGE_Energy_Inc_Consolidated_St1

MGE Energy Inc Consolidated Statements of Comprehensive Income (Unaudited) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Comprehensive Income [Abstract]	'	'	'	'
Net Income	$14,087	$13,891	$41,804	$36,475
Other comprehensive income (loss), net of tax:	'	'	'	'
Unrealized gain (loss) on available-for-sale securities, net of tax	-46	75	-39	140
Comprehensive Income	$14,041	$13,966	$41,765	$36,615

Madison_Gas_and_Electric_Compa1

Madison Gas and Electric Company Consolidated Statements of Comprehensive Income (Unaudited) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Other comprehensive income/(loss), net of tax:	'	'	'	'
Unrealized gain (loss) on available-for-sale securities, net of tax	($46)	$75	($39)	$140
Comprehensive Income	14,041	13,966	41,765	36,615
MGE [Member]	'	'	'	'
Net Income	14,143	13,965	41,786	36,525
Other comprehensive income/(loss), net of tax:	'	'	'	'
Unrealized gain (loss) on available-for-sale securities, net of tax	-116	1	-98	28
Total comprehensive income including noncontrolling interest	14,027	13,966	41,688	36,553
Less: Comprehensive income attributable to Noncontrolling Interest, net of tax	-6,621	-6,860	-13,131	-13,686
Comprehensive Income	$7,406	$7,106	$28,557	$22,867

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (Unaudited) (Parantheticals) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Unrealized gain (loss) on available-for-sale securities, tax (benefit) expense	($31)	$50	($26)	$93
MGE [Member]	'	'	'	'
Unrealized gain (loss) on available-for-sale securities, tax (benefit) expense	($77)	$1	($66)	$19

MGE_Energy_Inc_Consolidated_St2

MGE Energy Inc Consolidated Statements of Cash Flows (Unaudited) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Operating Activities:	'	'
Net Income	$41,804	$36,475
Items not affecting cash:	'	'
Depreciation and amortization	19,815	19,154
Deferred income taxes	15,110	20,484
Provision for doubtful receivables	984	1,084
Employee benefit plan expenses	-555	6,558
Equity earnings in ATC	-4,883	-4,705
Other items	-1,077	547
Changes in working capital items:	'	'
Decrease in current assets	17,349	17,350
Decrease in current liabilities	-5,840	-5,517
Dividend income from ATC	3,835	3,638
Cash contributions to pension and other postretirement plans	-1,633	-31,507
Other noncurrent items, net	-229	2,567
Cash Provided by Operating Activities	84,680	66,128
Investing Activities:	'	'
Capital expenditures	-42,272	-63,137
Capital contributions to investments	-1,225	-950
Other	-1,123	-458
Cash Used for Investing Activities	-44,620	-64,545
Financing Activities:	'	'
Cash dividends paid on common stock	-18,840	-18,264
Repayment of long-term debt	-2,042	-1,333
Increase in short-term debt	0	14,000
Other	-80	-10
Cash Used for Financing Activities	-20,962	-5,607
Change in cash and cash equivalents	19,098	-4,024
Cash and cash equivalents at beginning of period	68,813	46,357
Cash and Cash Equivalents at End of Period	87,911	42,333
Significant noncash investing activities:	'	'
Accrued capital expenditures	$9,442	$13,249

Madison_Gas_and_Electric_Compa2

Madison Gas and Electric Company Consolidated Statements of Cash Flows (Unaudited) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Items not affecting cash:	'	'
Depreciation and amortization	$19,815	$19,154
Deferred income taxes	15,110	20,484
Provision for doubtful receivables	984	1,084
Employee benefit plan expenses	-555	6,558
Equity earnings in ATC	-4,883	-4,705
Other items	-1,077	547
Changes in working capital items:	'	'
Decrease in current assets	17,349	17,350
Decrease in current liabilities	-5,840	-5,517
Dividend income from ATC	3,835	3,638
Cash contributions to pension and other postretirement plans	-1,633	-31,507
Other noncurrent items, net	-229	2,567
Cash Provided by Operating Activities	84,680	66,128
Investing Activities:	'	'
Capital expenditures	-42,272	-63,137
Capital contributions to investments	-1,225	-950
Other	-1,123	-458
Cash Used for Investing Activities	-44,620	-64,545
Financing Activities:	'	'
Repayment of long-term debt	-2,042	-1,333
Increase in short-term debt	0	14,000
Other	-80	-10
Cash Used for Financing Activities	-20,962	-5,607
Change in cash and cash equivalents	19,098	-4,024
Cash and cash equivalents at beginning of period	68,813	46,357
Cash and Cash Equivalents at End of Period	87,911	42,333
Significant noncash investing activities:	'	'
Accrued capital expenditures	9,442	13,249
MGE [Member]	'	'
Operating Activities:	'	'
Net Income	41,786	36,525
Items not affecting cash:	'	'
Depreciation and amortization	19,792	19,154
Deferred income taxes	14,566	19,804
Provision for doubtful receivables	984	1,084
Employee benefit plan expenses	-555	6,558
Equity earnings in ATC	-4,883	-4,705
Other items	-812	817
Changes in working capital items:	'	'
Decrease in current assets	17,169	17,013
Decrease in current liabilities	-3,536	-5,295
Dividend income from ATC	3,835	3,638
Cash contributions to pension and other postretirement plans	-1,633	-31,507
Other noncurrent items, net	-321	2,516
Cash Provided by Operating Activities	86,392	65,602
Investing Activities:	'	'
Capital expenditures	-42,272	-63,137
Capital contributions to investments	-1,065	-710
Other	-1,014	-422
Cash Used for Investing Activities	-44,351	-64,269
Financing Activities:	'	'
Cash dividends paid to parent by MGE	-16,750	0
Distributions to parent from noncontrolling interest	-12,838	-15,750
Equity contribution received by noncontrolling interest	1,065	710
Repayment of long-term debt	-2,042	-1,333
Increase in short-term debt	0	14,000
Cash Used for Financing Activities	-30,565	-2,373
Change in cash and cash equivalents	11,476	-1,040
Cash and cash equivalents at beginning of period	14,808	6,350
Cash and Cash Equivalents at End of Period	26,284	5,310
Significant noncash investing activities:	'	'
Accrued capital expenditures	$9,442	$13,249

Consolidated_Balance_Sheets_Un

Consolidated Balance Sheets (Unaudited) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current Assets:	'	'
Cash and cash equivalents	$87,911	$68,813
Accounts receivable, less reserves	37,685	44,890
Other accounts receivables, less reserves	5,390	5,352
Unbilled revenues	22,688	31,982
Materials and supplies, at average cost	17,991	16,662
Fossil fuel	4,410	5,206
Stored natural gas, at average cost	12,061	13,988
Prepaid taxes	17,420	19,106
Regulatory assets - current	3,563	6,377
Other current assets	9,663	8,225
Total Current Assets	218,782	220,601
Regulatory assets	98,268	107,166
Pension benefits	16,985	15,071
Other deferred assets and other	6,337	8,046
Property, Plant, and Equipment:	'	'
Property, plant, and equipment, net	1,112,755	1,018,809
Construction work in progress	73,710	141,415
Total Property, Plant, and Equipment	1,186,465	1,160,224
Investments	70,126	67,952
Total Assets	1,596,963	1,579,060
Current Liabilities:	'	'
Long-term debt due within one year	4,141	4,102
Accounts payable	43,078	43,684
Accrued interest and taxes	4,902	5,661
Accrued payroll related items	8,790	10,731
Deferred income taxes	1,267	1,711
Regulatory liabilities - current	10,021	13,538
Derivative liabilities	6,300	7,750
Other current liabilities	8,139	9,489
Total Current Liabilities	86,638	96,666
Other Credits:	'	'
Deferred income taxes	302,337	284,791
Investment tax credit - deferred	1,294	1,413
Regulatory liabilities	21,566	19,792
Accrued pension and other postretirement benefits	49,944	49,184
Derivative liabilities	45,490	57,930
Other deferred liabilities and other	51,993	52,360
Total Other Credits	472,624	465,470
Capitalization:	'	'
Common shareholders equity	640,355	617,510
Long-term debt	397,346	399,414
Total Capitalization	1,037,701	1,016,924
Commitments and contingencies (see Footnote 8)	'	'
Total Liabilities and Capitalization	1,596,963	1,579,060
MGE [Member]	'	'
Current Assets:	'	'
Cash and cash equivalents	26,284	14,808
Accounts receivable, less reserves	37,685	44,890
Affiliate receivables	611	534
Other accounts receivables, less reserves	5,329	5,274
Unbilled revenues	22,688	31,982
Materials and supplies, at average cost	17,991	16,662
Fossil fuel	4,410	5,206
Stored natural gas, at average cost	12,061	13,988
Prepaid taxes	22,315	23,934
Regulatory assets - current	3,563	6,377
Other current assets	9,654	8,197
Total Current Assets	162,591	171,852
Affiliate receivable long-term	5,560	5,825
Regulatory assets	98,268	107,166
Pension benefits	16,985	15,071
Other deferred assets and other	4,381	6,138
Property, Plant, and Equipment:	'	'
Property, plant, and equipment, net	1,111,845	1,017,877
Construction work in progress	73,710	141,415
Total Property, Plant, and Equipment	1,185,555	1,159,292
Investments	67,249	65,299
Total Assets	1,540,589	1,530,643
Current Liabilities:	'	'
Long-term debt due within one year	4,141	4,102
Accounts payable	43,077	43,684
Accrued interest and taxes	4,893	6,040
Accrued payroll related items	8,790	10,731
Deferred income taxes	2,279	2,723
Regulatory liabilities - current	10,021	13,538
Derivative liabilities	6,300	7,750
Other current liabilities	7,789	6,446
Total Current Liabilities	87,290	95,014
Other Credits:	'	'
Deferred income taxes	296,047	279,085
Investment tax credit - deferred	1,294	1,413
Regulatory liabilities	21,566	19,792
Accrued pension and other postretirement benefits	49,944	49,184
Derivative liabilities	45,490	57,930
Other deferred liabilities and other	51,993	52,357
Total Other Credits	466,334	459,761
Capitalization:	'	'
Common shareholders equity	469,298	457,491
Noncontrolling interest	120,321	118,963
Total Equity	589,619	576,454
Long-term debt	397,346	399,414
Total Capitalization	986,965	975,868
Commitments and contingencies (see Footnote 8)	'	'
Total Liabilities and Capitalization	$1,540,589	$1,530,643

Consolidated_Balance_Sheets_Un1

Consolidated Balance Sheets (Unaudited) (Parentheticals) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Receivables, Net	'	'
Reserve for uncollectible accounts receivable	$4,537	$4,219
Reserve for uncollectible other accounts receivable	534	750
MGE [Member]	'	'
Receivables, Net	'	'
Reserve for uncollectible accounts receivable	4,537	4,219
Reserve for uncollectible other accounts receivable	$534	$750

MGE_Energy_Inc_Consolidated_St3

MGE Energy Inc Consolidated Statements of Common Equity (Unaudited) (USD $)	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]
In Thousands, unless otherwise specified
Beginning balance, value at Dec. 31, 2012	$579,429	$34,668	$316,268	$228,399	$94
Beginning balance, shares at Dec. 31, 2012	'	34,668	'	'	'
Increase (Decrease) In Stockholders' Equity [Roll Forward]	'	'	'	'	'
Net Income	36,475	'	'	36,475	'
Other comprehensive income (loss)	140	'	'	'	140
Common stock dividends declared	-18,264	'	'	-18,264	'
Ending balance, value at Jun. 30, 2013	597,780	34,668	316,268	246,610	234
Ending balance, shares at Jun. 30, 2013	'	34,668	'	'	'
Beginning balance, value at Dec. 31, 2013	617,510	34,668	316,268	266,197	377
Beginning balance, shares at Dec. 31, 2013	'	34,668	'	'	'
Increase (Decrease) In Stockholders' Equity [Roll Forward]	'	'	'	'	'
Net Income	41,804	'	'	41,804	'
Other comprehensive income (loss)	-39	'	'	'	-39
Common stock dividends declared	-18,840	'	'	-18,840	'
Cash in lieu of fractional shares related to stock split	-80	'	'	-80	'
Ending balance, value at Jun. 30, 2014	$640,355	$34,668	$316,268	$289,081	$338
Ending balance, shares at Jun. 30, 2014	'	34,668	'	'	'

Madison_Gas_and_Electric_Compa3

Madison Gas and Electric Company Consolidated Statements of Common Equity (Unaudited) (USD $)	Total	MGE [Member]	Common Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss)/Income [Member]	Accumulated Other Comprehensive (Loss)/Income [Member]	Noncontrolling Interest [Member]
In Thousands, unless otherwise specified	USD ($)	USD ($)		MGE [Member]	MGE [Member]	MGE [Member]	USD ($)	MGE [Member]	MGE [Member]
				USD ($)	USD ($)	USD ($)		USD ($)	USD ($)
Beginning balance, value at Dec. 31, 2012	'	$550,766	'	$17,348	$192,417	$223,527	'	$4	$117,470
Beginning balance, shares at Dec. 31, 2012	'	'	34,668	17,348	'	'	'	'	'
Increase (Decrease) In Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'	'	'
Net Income	'	36,525	'	'	'	22,839	'	'	13,686
Other comprehensive income (loss)	140	28	'	'	'	'	140	28	'
Equity contribution received by noncontrolling interest	'	710	'	'	'	'	'	'	710
Distributions to parent from noncontrolling interest	'	-15,750	'	'	'	'	'	'	-15,750
Ending balance, value at Jun. 30, 2013	'	572,279	'	17,348	192,417	246,366	'	32	116,116
Ending balance, shares at Jun. 30, 2013	'	'	34,668	17,348	'	'	'	'	'
Beginning balance, value at Mar. 31, 2013	'	'	'	'	'	'	'	'	'
Increase (Decrease) In Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'	'	'
Net Income	'	13,965	'	'	'	'	'	'	'
Ending balance, value at Jun. 30, 2013	'	572,279	'	17,348	192,417	'	'	'	'
Ending balance, shares at Jun. 30, 2013	'	'	34,668	17,348	'	'	'	'	'
Beginning balance, value at Dec. 31, 2013	'	576,454	'	17,348	192,417	247,534	'	192	118,963
Beginning balance, shares at Dec. 31, 2013	'	'	34,668	17,348	'	'	'	'	'
Increase (Decrease) In Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'	'	'
Net Income	'	41,786	'	'	'	28,655	'	'	13,131
Other comprehensive income (loss)	-39	-98	'	'	'	'	-39	-98	'
Cash dividends paid to parent by MGE	'	-16,750	'	'	'	-16,750	'	'	'
Equity contribution received by noncontrolling interest	'	1,065	'	'	'	'	'	'	1,065
Distributions to parent from noncontrolling interest	'	-12,838	'	'	'	'	'	'	-12,838
Ending balance, value at Jun. 30, 2014	'	589,619	'	17,348	192,417	259,439	'	94	120,321
Ending balance, shares at Jun. 30, 2014	'	'	34,668	17,348	'	'	'	'	'
Beginning balance, value at Mar. 31, 2014	'	'	'	'	'	'	'	'	'
Increase (Decrease) In Stockholders' Equity [Roll Forward]	'	'	'	'	'	'	'	'	'
Net Income	'	14,143	'	'	'	'	'	'	'
Ending balance, value at Jun. 30, 2014	'	$589,619	'	$17,348	$192,417	'	'	'	'
Ending balance, shares at Jun. 30, 2014	'	'	34,668	17,348	'	'	'	'	'

Consolidated_Statements_of_Com1

Consolidated Statements of Common Equity (Unaudited) (Parentheticals) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Consolidated Statements of Common Equity	'	'	'	'
Dividends per share of common stock	$0.27	$0.26	$0.54	$0.53

Basis_of_Presentation

Basis of Presentation	6 Months Ended
	Jun. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Basis of Presentation	'
	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 guidance. MGE is considered the primary beneficiary of these entities as a result of contractual agreements. As a result, MGE has consolidated MGE Power Elm Road and MGE Power West Campus. See Footnote 2 of Notes to Consolidated Financial Statements under Item 8, Financial Statements and Supplementary Data, of MGE Energy's and MGE's 2013 Annual Report on Form 10-K.
	The accompanying consolidated financial statements as of June 30, 2014, and for the three and six 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 balance sheet information was derived from the audited balance sheet appearing in MGE Energy's and MGE's 2013 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 should be read in conjunction with the financial statements and the notes on pages 57 through 100 of the 2013 Annual Report on Form 10-K.
	On December 20, 2013, MGE Energy's Board of Directors declared a three-for-two stock split of MGE Energy's common stock in the form of a stock dividend. The additional shares were distributed February 7, 2014 to all shareholders of record as of January 24, 2014. All shares and per share data provided in this report give effect to this stock split.

Equity_and_Financing_Arrangeme

Equity and Financing Arrangements	6 Months Ended
	Jun. 30, 2014
Equity and Financing Arrangements Disclosure [Abstract]	'
Equity and Financing Arrangements	'
	Equity and Financing Arrangements.
	a. Common Stock - MGE Energy.
	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 six months ended June 30, 2014 and 2013, MGE Energy did not issue any new shares of common stock under the Stock Plan.
	b. Dilutive Shares Calculation - MGE Energy.
	MGE Energy does not hold any dilutive securities.

Investment_in_ATC

Investment in ATC	6 Months Ended
	Jun. 30, 2014
Equity Method Investments and Joint Ventures [Abstract]	'
Investment in ATC	'
	Investment in ATC - 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 is jointly owned by MGE Energy and MGE.
	MGE Transco has accounted for its investment in ATC under the equity method of accounting. For the six months ended June 30, 2014 and 2013, MGE Transco recorded the following:
				Six Months Ended
				June 30,
		(In thousands)		2014		2013
		Equity in earnings from investment in ATC	$	4,883	$	4,705
		Dividends received from ATC		3,835		3,638
		Capital contributions to ATC		1,065		710
	On July 31, 2014, MGE Transco made an additional $0.4 million capital contribution to ATC.
	MGE Transco's investment in ATC as of June 30, 2014 and December 31, 2013 was $66.6 million and $64.5 million, respectively.
	At June 30, 2014, MGE is the majority owner, and MGE Energy, the holding company, is the minority owner of MGE Transco. MGE Energy's proportionate share of the equity and net income of MGE Transco is classified within the MGE financial statements as noncontrolling interest.
	ATC's summarized financial data for the three and six months ended June 30, 2014 and 2013, is as follows:
				Three Months Ended				Six Months Ended
				June 30,				June 30,
		(In thousands)		2014		2013		2014		2013
		Operating revenues	$	159,990	$	152,128	$	323,327	$	303,865
		Operating expenses		-74,405		-69,875		-153,028		-139,645
		Other income (expense), net		322		116		710		-332
		Interest expense, net		-22,242		-21,052		-44,238		-42,096
		Earnings before members' income taxes	$	63,665	$	61,317	$	126,771	$	121,792

Columbia_Environmental_Project

Columbia Environmental Project Construction	6 Months Ended
	Jun. 30, 2014
Regulated Operations [Abstract]	'
Columbia Environmental Project Construction	'
	Columbia Environmental Project Construction - MGE Energy and MGE.
	MGE and two other utilities jointly own Columbia, a coal-fired generating facility. WPL is the plant operator and permit holder, and owns 46.2% of Columbia. WPSC owns a 31.8% interest, and MGE owns a 22% interest, in Columbia. In early 2011, the PSCW issued a Certificate and Order authorizing the construction of scrubbers and bag houses and associated equipment on Columbia Units 1 and 2 to reduce SO2 and mercury emissions. The modifications to Unit 2 were placed into service in April 2014, and the modifications to Unit 1 were placed into service in July 2014. The scrubbers and bag houses are expected to support compliance obligations for current and anticipated air quality regulations, including CAIR, CSAPR, MATS, and the Wisconsin Mercury Rule. As of June 30, 2014, $82.2 million of the capitalized project was transferred from Construction work in progress to Property, plant, and equipment on MGE’s balance sheet related to Unit 2 being placed into service. This total amount consisted of $76.9 million of capital expenditures and $5.3 million of AFUDC. As of June 30, 2014, capital expenditures and AFUDC related to Unit 1, which are classified as Construction work in progress on MGE’s balance sheet, were $50.6 million and $4.4 million, respectively. MGE's share of various contractual commitments entered for the project as of June 30, 2014 is $8.1 million. For the three months ended June 30, 2014 and 2013, MGE has recognized after tax $1.0 million and $0.6 million, respectively, in AFUDC equity related to this project. For the six months ended June 30, 2014 and 2013, MGE has recognized after tax $2.9 million and $1.1 million, respectively, in AFUDC equity related to this project.
	MGE expects that the costs pertaining to this project will be fully recoverable through rates. For 2014, the PSCW authorized MGE 100% AFUDC on this project during construction. For 2013, the PSCW authorized MGE a 50% current return (included in customer rates) and the remaining 50% as AFUDC.

Taxes

Taxes	6 Months Ended
	Jun. 30, 2014
Income Tax Disclosure [Abstract]	'
Taxes	'
	Taxes - MGE Energy and MGE.
	Effective Tax Rate.
	MGE Energy's and MGE's effective income tax rates for the three and six months ended June 30, 2014, were 39.1% and 37.7%, respectively, compared to 38.4% and 38.0% for the same periods in 2013. The net increase in the three month effective tax rate is attributable to changes in the level of the estimated 2014 manufacturing deduction.

Pension_and_Other_Postretireme

Pension and Other Postretirement Plans	6 Months Ended
	Jun. 30, 2014
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 defined contribution 401(k) benefit plans.
	The following table presents the components of MGE Energy's and MGE's net periodic benefit costs recognized for the three and six months ended June 30, 2014 and 2013. A portion of the net periodic benefit cost is capitalized within the consolidated balance sheets.
				Three Months Ended				Six Months Ended
				June 30,				June 30,
		(In thousands)		2014		2013		2014		2013
		Pension Benefits
		Components of net periodic (benefit) cost:
		Service cost	$	1,589	$	1,911	$	3,073	$	3,840
		Interest cost		3,483		3,157		6,735		6,343
		Expected return on assets		-5,656		-4,733		-10,935		-9,509
		Amortization of:
		Prior service (benefit) cost		53		79		102		158
		Actuarial loss		186		1,997		358		4,012
		Net periodic (benefit) cost	$	-345	$	2,411	$	-667	$	4,844
		Postretirement Benefits
		Components of net periodic (benefit) cost:
		Service cost	$	152	$	591	$	482	$	1,187
		Interest cost		356		962		1,127		1,932
		Expected return on assets		-301		-540		-955		-1,084
		Amortization of:
		Transition obligation		-		1		1		2
		Prior service (benefit) cost		-307		27		-974		55
		Actuarial loss		17		309		57		620
		Net periodic (benefit) cost	$	-83	$	1,350	$	-262	$	2,712

ShareBased_Compensation

Share-Based Compensation	6 Months Ended
	Jun. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Share-Based Compensation	'
	Share-Based Compensation - MGE Energy and MGE.
	Under MGE Energy's Performance Unit Plan, 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 set performance period.
	In addition to units granted in 2009 through 2013, on February 21, 2014, 21,991 units were granted based on the MGE Energy closing stock price as of that date. These units are subject to a five-year graded vesting schedule and have been adjusted to reflect the three-for-two stock split declared December 20, 2013. On the grant date, MGE Energy and MGE measure the cost of the employee services received in exchange for a performance unit award based on the current market value of MGE Energy common stock. The fair value of the awards has been subsequently re-measured at June 30, 2014, as required by applicable accounting standards. Changes in fair value have been recognized as compensation cost. Since this amount is re-measured quarterly throughout the vesting period, the compensation cost is subject to variability.
	For nonretirement eligible employees, stock based compensation costs are accrued and recognized using the graded vesting method. Compensation cost for retirement eligible employees or employees that will become retirement eligible during the vesting schedule are recognized on an abridged horizon.
	In December 2013, a Director Incentive Plan was approved for the non-employee members of the Board of Directors. This plan is similar to MGE Energy's Performance Unit Plan for eligible employees described above. Under the plan, a non-employee director can 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 payments, at the end of the set performance period. The units are subject to a three-year graded vesting schedule. In January 2014, unit awards of 4,683 (post-split) were granted to the non-employee Directors. For accounting purposes, the awards will be measured similarly to the employee unit awards.
	During the six months ended June 30, 2014 and 2013, MGE recorded $1.1 million and $1.0 million, respectively, in compensation expense as a result of the plans. In January 2014, cash payments of $1.2 million were distributed relating to awards that were granted in 2009. No forfeitures occurred during the six months ended June 30, 2014 or 2013. At June 30, 2014, $3.9 million of outstanding awards are vested.

Commitments_and_Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies - MGE Energy and MGE.
	a. Environmental.
	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. Regulatory initiatives, proposed rules, and court challenges to adopted rules, have the potential to have a material effect on our capital expenditures and operating costs. These initiatives, proposed rules, and court challenges include:
	The President's announced plan and directive to the EPA to regulate carbon pollution, or greenhouse gas (GHG) emissions, from new and existing electric power generation units, and the EPA's related proposed GHG New Source Performance Standards (NSPS) (see below for additional information on the NSPS rule).
	Rules to regulate NOx and SO2 emissions, including the EPA's Cross State Air Pollution Rule (CSAPR) (see below for recent developments with CSAPR). The Sierra Club has sought federal appellate court review of Wisconsin's implementation plan addressing regional haze pursuant to the Clean Air Visibility Rule (CAVR). Both the pending challenges to CSAPR and the appellate court review of Wisconsin's implementation plan for regional haze make the nature of compliance requirements uncertain.
	Rules to regulate mercury and similar emissions, including Wisconsin's adopted Mercury Rule and the EPA's adopted Mercury and Air Toxics Standards.
	The EPA's cooling water intake rules. The EPA issued a final rule for existing facilities in May 2014. The final rule is discussed below.
	The EPA's proposed water effluent limitations guidelines and standards for steam electric power plants, which focus on the reduction of metals and other pollutants in wastewater from new and existing power plants from coal-burning plants such as Columbia and the Elm Road Units.
	The EPA's ongoing review of several National Ambient Air Quality Standards (NAAQS), including the potential lowering of the ozone NAAQS and its proposed requirements for air agencies to characterize sulfur dioxide air quality for purposes of implementing the 1-hour SO2 NAAQS. This approach focuses on large sources of SO2 emissions and proposes area designations to be made in two rounds (2017 and 2020). The proposed rule gives states broad discretion in its implementation. The final rule is expected late in 2014. MGE will be reviewing the rule for potential impacts on its operations.
	The EPA is reconsidering the current emergency dispatch restrictions in the Reciprocating Internal Combustion Engines Maximum Achievable Control Technology (RICE MACT) regulation. The reconsideration could result in increased or decreased restrictions for these engines.
	The matters in the bullet points above are discussed further in Footnote 18.d. in the Financial Statements of MGE Energy's and MGE's 2013 Annual Report on Form 10-K. In addition to the developments noted above, the following discussion is an update to the current status of environmental matters set forth in that Footnote.
	EPA’s Final 316(b) Rule Governing Water Intake Systems at Electric Generating Facilities
	In May 2014, the EPA finalized its Phase II and III Rules pursuant to Section 316(b) of the Clean Water Act, which governs cooling water intake structures located at large existing power plant and industrial facilities. The 316(b) Rule requires these facilities to implement methods for reducing fish impingement by their water intakes using one of seven options, including closed cycle cooling (CCC) systems.
	MGE expects that this 316(b) Rule will not have material effects on its existing plants. Our WCCF facility already employs a CCC system as defined under the Rule. Our Columbia plant may need to address multiple intake structures. Our Blount plant has conducted studies on our effects and for options for compliance with this rule. Our exact requirements at Blount and Columbia, however, will not be known until those sites’ permits are modified to account for this rule.
	EPA's Cross-State Air Pollution Rule (CSAPR) Upheld by the Supreme Court
	On April 29, 2014, the US Supreme Court issued a decision reversing the D.C. Circuit Court's decision that had vacated CSAPR and remanding the matter back to the D.C. Circuit for further proceedings. CSPAR remains subject to an order of the D.C. Circuit that stayed its implementation pending resolution of the appeals. The State of Wisconsin has since filed a motion with the D.C. Circuit Court reiterating its contention that Wisconsin be removed from CSAPR. The EPA has also asked the D.C. Circuit Court to lift the stay order and extend the existing CSAPR compliance deadlines by three years. That motion has not been decided. Thus there is remaining uncertainty as to whether MGE’s facilities will be required to meet the CSAPR mandates and if so, the deadline for achieving compliance. The Clean Air Interstate Rule (CAIR) remains in effect for the time being. See MGE Energy's and MGE's 2013 Annual Report on Form 10K for additional information on the legal proceedings associated with these environmental matters.
	Evaluations of CSAPR have concluded that compliance would require further controls on SO2 emissions to be installed at our Columbia plant. The Columbia Consent Decree also requires installation of SO2 controls which would help meet the CSAPR requirements. Installation of Unit 2 and Unit 1 SO2 controls were completed in April 2014 and July 2014, respectively (see Footnote 4 for information regarding the Columbia environmental construction project). MGE expects that the costs pertaining to meeting CSAPR and the Consent Decree requirements will be fully recoverable through rates. We will continue to monitor and evaluate the D.C. Circuit Court remand proceedings and the implementation of the rule by the EPA and WDNR.
	EPA’s Greenhouse Gas Reduction Guidelines under the Clean Air Act 111(d) Rule
	On June 2, 2014, the EPA released proposed guidelines for states to use in developing plans to control GHG emissions from existing fossil fuel fired electric generating units (EGUs). The proposed rule was published in the Federal Register on June 17, 2014.
	The EPA’s proposal seeks to reduce GHG emissions from EGUs by a national average of 30% by 2030 as measured from a 2005 baseline. Each state is given its own emission reduction targets to meet this goal. These targets are expressed as a “rate-based” emission average to be achieved by the combined fleet of EGUs within the state. States would be expected to make “meaningful progress” towards these reductions by 2020 and to meet their respective targets by 2030.
	The EPA’s proposal establishes guidelines for states and encourages the use of four options for achieving these reductions. These options are referred to as “building blocks” and are: (1) increasing the efficiency of EGUs; (2) re-dispatching of gas-fired generation at the expense of coal; (3) expanding the use of low and no carbon power sources such as wind, nuclear and solar; and (4) improving demand side energy efficiency to reduce electric use.
	The EPA is taking comments on the proposed rule through mid-October 2014. The rule is expected to be finalized by June 2015. States will then have up to two years to prepare compliance plans. This rule could have significant impacts on EGUs. MGE is reviewing the proposal at this time.
	Coal Combustion Residual Rule
	The EPA’s Coal Combustion Residual (CCR) Rule is currently in the proposed stage but is anticipated to be finalized in December 2014. The final CCR Rule will regulate disposal and management of ash and other coal combustion byproducts as a waste under the EPA’s solid waste rules.
	Columbia
	Based upon current available information, compliance with various environmental requirements and initiatives is expected to result in significant additional operating and capital expenditures at Columbia as noted below.
	Columbia Environmental Project
	See Footnote 4 for information regarding the Columbia environmental construction project.
	Columbia Clean Air Act Litigation
	In December 2009, the EPA sent a notice of violation (NOV) to MGE and the other co-owners of Columbia. The NOV alleges that WPL, as owner-operator, and the other co-owners failed to comply with appropriate pre-construction review and permitting requirements and, as a result, violated the PSD program requirements, the Title V operating permit requirements of the CAA and the Wisconsin State Implementation Plan (SIP). In April 2013, the EPA filed a lawsuit against the co-owners of Columbia asserting similar allegations. In September 2010 and April 2013, Sierra Club filed lawsuits against WPL alleging violations of the CAA at Columbia and other WPL-operated Wisconsin facilities.
	In April 2013, WPL, as owner-operator, along with the other owners of Columbia, entered into a consent decree with the EPA and the Sierra Club to resolve these claims, while admitting no liability. In June 2013, the consent decree was approved and entered by the Court. The consent decree requires installation of the following emission controls at Columbia: SO2 scrubbers and baghouses at Columbia Units 1 and 2 by December 31, 2014, which have now been installed, and an SCR system at Columbia Unit 2 by December 31, 2018. In addition, the consent decree establishes emission rate limits for SO2, NOx, and particulate matter for Columbia Units 1 and 2. The consent decree also includes annual plant-wide emission caps for SO2 and NOx for Columbia. MGE also paid approximately $0.2 million as its share of a civil penalty and will complete approximately $0.6 million in environmental mitigation projects. MGE intends to seek recovery in rates of the costs associated with its compliance with the terms of the final consent decree and currently expects to recover any material compliance costs.
	b. Chattel Paper Agreement and Other Guarantees.
	MGE makes available to qualifying customers a financing program for the purchase and installation of energy-related equipment that will provide more efficient use of utility service at the customer's property. MGE is party to a chattel paper purchase agreement with a financial institution under which it can sell or finance an undivided interest with recourse, in up to $10.0 million of the financing program receivables, until July 31, 2015. At June 30, 2014, MGE had sold a $4.3 million interest in these receivables. MGE retains the servicing responsibility for these receivables. As of June 30, 2014, the servicing asset recognized by MGE is $0.2 million.
	MGE accounts for servicing rights under the amortization method. Initial determination of the servicing asset fair value is based on the present value of the estimated future cash flows. The discount rate is based on the PSCW authorized weighted cost of capital.
	MGE would be required to perform under its guarantee if a customer defaulted on its loan. The energy-related equipment installed at the customer sites is used to secure the customer loans. The loan balances outstanding at June 30, 2014, approximate the fair value of the energy-related equipment acting as collateral. The length of the MGE guarantee to the financial institution varies from one to ten years depending on the term of the underlying customer loan. Principal payments for the remainder of 2014 and the next four years on the loans are:
		(In thousands)		2014		2015		2016		2017		2018
		Chattel Paper	$	262	$	914	$	834	$	431	$	374
	c. Legal Matters.
	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.
	d. Purchase Contracts.
	MGE Energy and MGE have entered into various commodity supply, transportation, and storage contracts to meet their obligations to deliver electricity and natural gas to customers. As of June 30, 2014, the future commitments related to these purchase contracts were as follows:
		(In thousands)		2014		2015		2016		2017		2018
		Natural gas supply(a)	$	17,911	$	16,840	$	-	$	-	$	-
		Purchase power(b)		50,569		49,086		49,757		50,257		51,279
		Other		17,111		-		-		-		-
			$	85,591	$	65,926	$	49,757	$	50,257	$	51,279
	(a) These commitments include market-based pricing. Management expects to recover these costs in future customer rates.
	(b) MGE has several purchase power agreements to help meet future electric supply requirements. Management expects to recover these costs in future customer rates.
	e. Elm Road - MGE Energy and MGE.
	The warranty periods for both of the Elm Road Units have expired. During 2013, WEPCO and Bechtel (the construction contractor for the Elm Road Units) were working through the outstanding warranty claims. The warranty claim for the costs incurred to repair steam turbine corrosion damage identified on both units was resolved through a binding arbitration in June 2013. Final acceptance of the Elm Road Units occurred in June 2013 after all requirements stated in the contract with Bechtel were satisfied. In April 2014, an additional warranty claim was resolved that did not have a material impact on our financial statements. The parties continue to work through one potential remaining warranty claim.

Derivative_and_Hedging_Instrum

Derivative and Hedging Instruments	6 Months Ended
	Jun. 30, 2014
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 and gas revenues. To the extent that these contracts are derivatives, MGE assesses whether or not the normal purchases or normal sales exclusion applies. For contracts to which this exclusion cannot be applied, MGE Energy and MGE recognize such derivatives in the consolidated balance sheets at fair value. The majority of MGE's derivative activities are conducted 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 can 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. 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 rates as a component of the fuel rules mechanism.
	b. Notional Amounts.
	The gross notional volume of open derivatives is as follows:
			30-Jun-14		31-Dec-13
		Commodity derivative contracts	431,510 MWh		458,660 MWh
		Commodity derivative contracts	4,382,500 Dth		3,750,000 Dth
		FTRs	4,597 MW		1,984 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 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 points on the transmission grid. The fair values of these instruments are offset with a corresponding 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. At June 30, 2014 and December 31, 2013, the fair value of exchange traded derivatives and FTRs exceeded their cost basis by $2.9 million and $1.8 million, respectively.
	MGE is a party to a ten-year 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. 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 at June 30, 2014 and December 31, 2013, reflects a loss position of $51.8 million and $65.7 million, respectively. The actual fuel cost will be recognized in purchased power expense in the month of purchase.
	The following table summarizes the fair value of the derivative instruments on the consolidated balance sheet. 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 agreement as well as the netting of collateral. For financial statement purposes, MGE Energy and MGE have netted instruments with the same counterparty under a master netting agreement as well as the netting of collateral.
			Asset Derivatives				Liability Derivatives
	(In thousands)		Balance Sheet Location		Fair Value		Balance Sheet Location		Fair Value
	30-Jun-14
	Commodity derivative contracts		Other current assets	$	1,970		Derivative liability (current)	$	225
	Commodity derivative contracts		Other deferred charges		101		Derivative liability (long-term)		49
	FTRs		Other current assets		1,139		Derivative liability (current)		-
	Ten-year PPA		N/A		N/A		Derivative liability (current)		6,300
	Ten-year PPA		N/A		N/A		Derivative liability (long-term)		45,490
	31-Dec-13
	Commodity derivative contracts		Other current assets	$	1,356		Derivative liability (current)	$	51
	Commodity derivative contracts		Other deferred charges		167		Derivative liability (long-term)		48
	FTRs		Other current assets		363		Derivative liability (current)		-
	Ten-year PPA		N/A		N/A		Derivative liability (current)		7,750
	Ten-year PPA		N/A		N/A		Derivative liability (long-term)		57,930
	The following tables show the effect of netting arrangements for recognized derivative assets and liabilities that are subject to a master netting arrangement or similar arrangement on the balance sheet.
		Offsetting of Derivative Assets
		(In thousands)		Gross amounts		Gross amounts offset in balance sheet		Collateral posted against derivative positions		Net amount presented in balance sheet
		30-Jun-14
		Commodity derivative contracts	$	2,071	$	-274	$	-292	$	1,505
		FTRs		1,139		-		-		1,139
		31-Dec-13
		Commodity derivative contracts	$	1,523	$	-99	$	-175	$	1,249
		FTRs		363		-		-		363
		Offsetting of Derivative Liabilities
		(In thousands)		Gross amounts		Gross amounts offset in balance sheet		Collateral posted against derivative positions		Net amount presented in balance sheet
		30-Jun-14
		Commodity derivative contracts	$	274	$	-274	$	-	$	-
		Ten-year PPA		51,790		-		-		51,790
		31-Dec-13
		Commodity derivative contracts	$	99	$	-99	$	-	$	-
		Ten-year PPA		65,680		-		-		65,680
	The following tables summarize the unrealized and realized gains (losses) related to the derivative instruments on the consolidated balance sheet at June 30, 2014 and 2013, and the consolidated income statement for the three and six months ended June 30, 2014 and 2013.
			2014					2013
	(In thousands)		Current and long-term regulatory asset		Other current assets			Current and long-term regulatory asset		Other current assets
	Three Months Ended June 30:
	Balance at April 1,	$	58,213	$	351		$	69,197	$	259
	Change in unrealized gain		-9,817		-			-1,963		-
	Realized gain (loss) reclassified to a deferred
	account		-101		101			-388		388
	Realized gain (loss) reclassified to income
	statement		559		224			-197		11
	Balance at June 30,	$	48,854	$	676		$	66,649	$	658
	Six Months Ended June 30:
	Balance at January 1,	$	63,893	$	411		$	72,329	$	574
	Change in unrealized gain		-23,418		-			-3,660		-
	Realized gain (loss) reclassified to a deferred
	account		1,434		-1,434			-678		678
	Realized gain (loss) reclassified to income
	statement		6,945		1,699			-1,342		-594
	Balance at June 30,	$	48,854	$	676		$	66,649	$	658
		Realized losses (gains)
	(In thousands)		Fuel for electric generation/ purchased power		Cost of gas sold
	Three Months Ended June 30, 2014:
	Commodity derivative contracts	$	-1,061	$	-128
	FTRs		-196		-
	Ten-year PPA		602		-
	Three Months Ended June 30, 2013:
	Commodity derivative contracts	$	-538	$	-
	FTRs		-351		-
	Ten-year PPA		1,075		-
	Six Months Ended June 30, 2014:
	Commodity derivative contracts	$	-5,856	$	-1,349
	FTRs		-832		-
	Ten-year PPA		-607		-
	Six Months Ended June 30, 2013:
	Commodity derivative contracts	$	-516	$	608
	FTRs		-509		-
	Ten-year PPA		2,353		-
MGE's commodity derivative contracts, FTRs, and ten-year 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 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 ten-year 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 June 30, 2014, no collateral has been posted. Certain counterparties extend MGE a credit limit. If MGE exceeds these limits, the counterparties may require collateral to be posted. As of June 30, 2014 and December 31, 2013, 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 June 30, 2014, no counterparties have defaulted.

Rate_Matters

Rate Matters	6 Months Ended
	Jun. 30, 2014
Regulated Operations [Abstract]	'
Rate Matters	'
	Rate Matters - MGE Energy and MGE.
	a. Rate Proceedings.
	On April 17, 2014, MGE filed an application with the PSCW requesting a 2.8% increase to electric rates and a 2.3% decrease to gas rates for 2015. Electric and natural gas rates would then be frozen at 2015 levels in 2016, subject to review of fuel costs. As a condition of the rate freeze, MGE has requested escrow accounting treatment for transmission related costs starting in 2015. This treatment will allow MGE to reflect any differential between costs reflected in rates and actual costs incurred in its next rate case filing. The proposed electric rate increases cover costs associated with the construction of emission-reduction equipment at Columbia and improvements and reliability of the state's electric transmission system.
	On July 26, 2013, the PSCW authorized MGE to freeze electric and natural gas rates at 2013 levels for 2014. The order includes authorizing 100% AFUDC on the Columbia scrubber construction project and deferral of increased costs related to ATC and MISO Schedule 26 fees. As part of the rate freeze plan authorized by the PSCW, effective January 1, 2014 approximately $6.2 million associated with a 2012 fuel rule surplus credit will not be required to be refunded to customers and will be amortized in 2014. The fuel credit will accrue interest at MGE's weighted cost of capital. The authorized return on equity will remain unchanged at 10.3%.
	On December 14, 2012, the PSCW authorized MGE to increase 2013 rates for retail electric customers by 3.8% or $14.9 million and to increase gas rates by 1.0% or $1.6 million. The change in retail electric rates was driven by costs for new environmental equipment at Columbia, final construction costs for the Elm Road Units, transmission reliability enhancements, and purchased power costs. The authorized return on common stock equity remains unchanged at 10.3%.
	b. 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 most recent base rate proceedings. Any over/under recovery of the actual costs is determined on an annual basis and will be adjusted 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, less 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 return 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 that order.
	As of June 30, 2014, MGE did not defer any electric fuel-related savings/costs that are outside the range authorized by the PSCW. As part of the rate freeze plan authorized by the PSCW for 2014, $3.2 million of the approximately $6.2 million associated with the 2012 fuel rule surplus credit was amortized against purchase power expense during the six months ended June 30, 2014.

Fair_Value_of_Financial_Instru

Fair Value of Financial Instruments	6 Months Ended
	Jun. 30, 2014
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 standard clarifies that fair value should be based on the assumptions market participants would use when pricing the asset or liability including assumptions about risk. The standard 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 prices 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 model-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.
	At June 30, 2014 and December 31, 2013, the carrying amount of cash and cash equivalents approximates fair market value due to the short maturity of those investments and obligations. The estimated fair market value of MGE Energy's and MGE's long-term debt is based on quoted market prices for similar financial instruments at June 30, 2014 and December 31, 2013. Since long-term debt is not traded in an active market, it is classified as Level 2. The estimated fair market value of MGE Energy's and MGE's financial instruments are as follows:
				30-Jun-14					31-Dec-13
		(In thousands)		Carrying Amount		Fair Value			Carrying Amount		Fair Value
		MGE Energy
		Assets:
		Cash and cash equivalents	$	87,911	$	87,911		$	68,813	$	68,813
		Liabilities:
		Long-term debt*		401,751		444,752			403,793		432,010
		MGE
		Assets:
		Cash and cash equivalents	$	26,284	$	26,284		$	14,808	$	14,808
		Liabilities:
		Long-term debt*		401,751		444,752			403,793		432,010
		*Includes long-term debt due within one year.
	b. Recurring Fair Value Measurements.
	The following table presents the balances of assets and liabilities measured at fair value on a recurring basis for MGE Energy and MGE.
				Fair Value as of June 30, 2014
		(In thousands)		Total		Level 1		Level 2		Level 3
		MGE Energy
		Assets:
		Exchange-traded investments	$	727	$	727	$	-	$	-
		Total Assets	$	727	$	727	$	-	$	-
		Liabilities:
		Derivatives, net(a)	$	48,854	$	-495	$	-	$	49,349
		Deferred compensation		2,591		-		2,591		-
		Total Liabilities	$	51,445	$	-495	$	2,591	$	49,349
		MGE
		Assets:
		Exchange-traded investments	$	268	$	268	$	-	$	-
		Total Assets	$	268	$	268	$	-	$	-
		Liabilities:
		Derivatives, net(a)	$	48,854	$	-495	$	-	$	49,349
		Deferred compensation		2,591		-		2,591		-
		Total Liabilities	$	51,445	$	-495	$	2,591	$	49,349
				Fair Value as of December 31, 2013
		(In thousands)		Total		Level 1		Level 2		Level 3
		MGE Energy
		Assets:
		Exchange-traded investments	$	792	$	792	$	-	$	-
		Total Assets	$	792	$	792	$	-	$	-
		Liabilities:
		Derivatives, net(a)	$	63,893	$	-735	$	-	$	64,628
		Deferred compensation		2,364		-		2,364		-
		Total Liabilities	$	66,257	$	-735	$	2,364	$	64,628
		MGE
		Assets:
		Exchange-traded investments	$	431	$	431	$	-	$	-
		Total Assets	$	431	$	431	$	-	$	-
		Liabilities:
		Derivatives, net(a)	$	63,893	$	-735	$	-	$	64,628
		Deferred compensation		2,364		-		2,364		-
		Total Liabilities	$	66,257	$	-735	$	2,364	$	64,628
		(a) These amounts are shown gross and exclude $0.3 million and $0.2 million of collateral that was
		posted against derivative positions with counterparties as of June 30, 2014 and
		December 31, 2013, respectively.
	No transfers were made in or out of Level 1 or Level 2 for the six months ended June 30, 2014.
	Investments include exchange-traded investment securities valued using quoted prices on active exchanges and are therefore classified as Level 1.
Derivatives include exchange-traded derivative contracts, over-the-counter transactions, a ten-year purchased power agreement, and FTRs. Most exchange-traded derivative contracts are valued based on unadjusted quoted prices in active markets and are therefore classified 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 classified as Level 3. Transactions done with an over-the-counter party are on inactive markets and are therefore considered unobservable and 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 similar instruments in a closed market with limited data available and are therefore classified as Level 3.
The ten-year purchased power agreement (see Footnote 9) 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 judgment and estimation. Future energy prices are based on a forward power pricing curve using exchange-traded contracts in the electric futures market, where such exchange-traded contracts exist, and upon calculations based on forward gas prices, where such exchange-traded contracts do not exist. A basis adjustment is applied to the market energy price to reflect the price differential between the market price delivery point and the counterparty 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. If 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 determined 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 assumptions 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.
This model is prepared by members of MGE's Energy Accounting group. It is reviewed on a quarterly basis by management in Energy Supply and Finance to review the assumptions, inputs, and fair value measurements.
The following table presents the significant unobservable inputs used in the pricing model.
	Significant Unobservable Inputs		Model Input
	Basis adjustment:
	On peak		96.90%
	Off peak		94.20%
	Counterparty fuel mix:
	Internal generation		50% - 70%
	Purchased power		50% - 30%
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 of MGE Energy and MGE. The notional investments earn interest based upon the semiannual rate of U.S. Treasury Bills having a 26 week 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 assets and liabilities measured at fair value on a recurring basis for both MGE Energy and MGE.
		Three Months Ended				Six Months Ended
		June 30,				June 30,
(In thousands)		2014		2013		2014		2013
Beginning balance,	$	-58,797	$	-69,598	$	-64,628	$	-72,346
Realized and unrealized gains (losses):
Included in regulatory liabilities (assets)		9,448		2,743		15,279		5,490
Included in other comprehensive income		-		-		-		-
Included in earnings		651		-44		7,218		-1,351
Included in current assets		-185		-123		-185		-123
Purchases		6,828		6,162		13,634		11,724
Sales		-		-		-60		-2
Issuances		-		-		-		-
Settlements		-7,294		-5,996		-20,607		-10,248
Transfers in and/or out of Level 3		-		-		-		-
Balance as of June 30,	$	-49,349	$	-66,856	$	-49,349	$	-66,856
Total gains (losses) included in earnings attributed to
the change in unrealized gains (losses) related to
assets and liabilities held at June 30,(b)	$	-	$	-	$	-	$	-
The following table presents total realized and unrealized gains (losses) included in income for Level 3 assets and liabilities measured at fair value on a recurring basis for both MGE Energy and MGE (b).
			Three Months Ended				Six Months Ended
			June 30,				June 30,
	(In thousands)		2014		2013		2014		2013
	Purchased Power Expense	$	651	$	-44	$	7,218	$	-1,351
(b) MGE's exchange-traded derivative contracts, over-the-counter party transactions, ten-year purchased power agreement, and FTRs are subject to regulatory deferral. These derivatives are therefore marked to fair value and are offset with a corresponding regulatory asset or liability.

New_Accounting_Pronouncements

New Accounting Pronouncements	6 Months Ended
	Jun. 30, 2014
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]	'
New Accounting Pronouncements	'
	New Accounting Pronouncements - MGE Energy and MGE.
	a. Obligations Resulting from Joint and Several Liability Arrangements for Which the Total Amount of the Obligation is Fixed at the Reporting Date.
	In February 2013, the FASB issued authoritative guidance within the Codification's Balance Sheet topic that provides guidance on the recognition, measurement, and disclosure of obligations resulting from joint and several liability arrangements for which the total amount of the obligation is fixed at the reporting date. This authoritative guidance became effective January 1, 2014. The authoritative guidance did not have a financial or disclosure impact.
	b. Presentation of an Unrecognized Tax Benefit.
	In July 2013, the FASB issued authoritative guidance within the Codification's Income Statement topic that provides guidance on the presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. The authoritative guidance was issued to eliminate diversity in practice by providing guidance on the presentation of unrecognized tax benefits. This authoritative guidance became effective January 1, 2014. The authoritative guidance will not have a financial statement or disclosure impact, unless MGE Energy or its subsidiaries are in a net operating loss position. MGE Energy or its subsidiaries are currently not in a net operating loss position.
	c. Revenue from Contracts with Customers.
	In May 2014, the FASB issued authoritative guidance within the Codification's Revenue Recognition topic that provides guidance on the recognition, measurement, and disclosure of revenue from contracts with customers. This authoritative guidance will become effective January 1, 2017. MGE Energy and MGE are currently assessing the impact this pronouncement will have on their financial statements.
	d. Transfers and Servicing Assets.
	In June 2014, the FASB issued authoritative guidance within the Codification's Transfers and Servicing topic that provides guidance on the accounting and disclosures for repurchase-to-maturity transactions, securities lending transactions, and repurchase financings. This authoritative guidance will become effective January 1, 2015. MGE Energy and MGE are currently assessing the impact this pronouncement will have on their financial statements.

Segment_Information

Segment Information	6 Months Ended
	Jun. 30, 2014
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 MGE Energy's and MGE's 2013 Annual Report on Form 10-K for additional discussion of each of these segments.
	The following tables show segment information for MGE Energy's operations for the indicated periods:
	(In thousands)MGE Energy		Electric		Gas		Non- Regulated Energy		Transmission Investment		All Others		Consolidation/ Elimination Entries		Consolidated Total
	Three Months Ended June 30, 2014
	Operating revenues	$	96,697	$	31,218	$	850	$	-	$	-	$	-	$	128,765
	Interdepartmental revenues		127		1,892		10,673		-		-		-12,692		-
	Total operating revenues		96,824		33,110		11,523		-		-		-12,692		128,765
	Depreciation and amortization		-6,641		-1,562		-1,855		-		-11		-		-10,069
	Other operating expenses		-76,812		-29,865		-30		-		-240		12,692		-94,255
	Operating income (loss)		13,371		1,683		9,638		-		-251		-		24,441
	Other (deductions) income, net		1,036		-17		-		2,402		127		-		3,548
	Interest (expense) income, net		-2,534		-817		-1,559		-		42		-		-4,868
	Income (loss) before taxes		11,873		849		8,079		2,402		-82		-		23,121
	Income tax (provision) benefit		-4,491		-364		-3,242		-963		26		-		-9,034
	Net income (loss)	$	7,382	$	485	$	4,837	$	1,439	$	-56	$	-	$	14,087
	Three Months Ended June 30, 2013
	Operating revenues	$	96,846	$	30,042	$	1,400	$	-	$	-	$	-	$	128,288
	Interdepartmental revenues		129		2,816		10,691		-		-		-13,636		-
	Total operating revenues		96,975		32,858		12,091		-		-		-13,636		128,288
	Depreciation and amortization		-6,314		-1,435		-1,781		-		-		-		-9,530
	Other operating expenses		-78,051		-29,572		-26		-		-248		13,636		-94,261
	Operating income (loss)		12,610		1,851		10,284		-		-248		-		24,497
	Other (deductions) income, net		485		-185		-		2,309		102		-		2,711
	Interest (expense) income, net		-2,315		-759		-1,605		-		22		-		-4,657
	Income (loss) before taxes		10,780		907		8,679		2,309		-124		-		22,551
	Income tax (provision) benefit		-3,694		-606		-3,483		-927		50		-		-8,660
	Net income (loss)	$	7,086	$	301	$	5,196	$	1,382	$	-74	$	-	$	13,891
	Six Months Ended June 30, 2014
	Operating revenues	$	195,549	$	141,931	$	1,530	$	-	$	-	$	-	$	339,010
	Interdepartmental revenues		245		5,516		21,343		-		-		-27,104		-
	Total operating revenues		195,794		147,447		22,873		-		-		-27,104		339,010
	Depreciation and amortization		-12,978		-3,125		-3,689		-		-23		-		-19,815
	Other operating expenses		-154,713		-122,708		-70		-		-396		27,104		-250,783
	Operating income (loss)		28,103		21,614		19,114		-		-419		-		68,412
	Other (deductions) income, net		2,863		-52		-		4,883		406		-		8,100
	Interest (expense) income, net		-4,739		-1,621		-3,131		-		82		-		-9,409
	Income before taxes		26,227		19,941		15,983		4,883		69		-		67,103
	Income tax provision		-8,844		-8,029		-6,414		-1,961		-51		-		-25,299
	Net income	$	17,383	$	11,912	$	9,569	$	2,922	$	18	$	-	$	41,804
	Six Months Ended June 30, 2013
	Operating revenues	$	190,340	$	102,509	$	2,676	$	-	$	-	$	-	$	295,525
	Interdepartmental revenues		238		7,692		21,264		-		-		-29,194		-
	Total operating revenues		190,578		110,201		23,940		-		-		-29,194		295,525
	Depreciation and amortization		-12,714		-2,860		-3,580		-		-		-		-19,154
	Other operating expenses		-152,976		-90,009		-63		-		-392		29,194		-214,246
	Operating income (loss)		24,888		17,332		20,297		-		-392		-		62,125
	Other (deductions) income, net		1,060		-23		-		4,705		278		-		6,020
	Interest (expense) income, net		-4,719		-1,437		-3,218		-		42		-		-9,332
	Income (loss) before taxes		21,229		15,872		17,079		4,705		-72		-		58,813
	Income tax (provision) benefit		-7,127		-6,595		-6,740		-1,898		22		-		-22,338
	Net income (loss)	$	14,102	$	9,277	$	10,339	$	2,807	$	-50	$	-	$	36,475
	The following tables show segment information for MGE's operations for the indicated periods:
	(In thousands)MGE		Electric		Gas		Non- Regulated Energy		Transmission Investment		Consolidation/ Elimination Entries		Consolidated Total
	Three Months Ended June 30, 2014
	Operating revenues	$	96,702	$	31,223	$	850	$	-	$	-	$	128,775
	Interdepartmental revenues		122		1,887		10,673		-		-12,682		-
	Total operating revenues		96,824		33,110		11,523		-		-12,682		128,775
	Depreciation and amortization		-6,641		-1,562		-1,855		-		-		-10,058
	Other operating expenses*		-81,165		-30,188		-3,272		-		12,682		-101,943
	Operating income*		9,018		1,360		6,396		-		-		16,774
	Other (deductions) income, net*		898		-58		-		1,439		-		2,279
	Interest expense, net		-2,534		-817		-1,559		-		-		-4,910
Net income		7,382		485		4,837		1,439		-		14,143
Less: Net income attributable to
noncontrolling interest, net of tax		-		-		-		-		-6,621		-6,621
Net income attributable to MGE	$	7,382	$	485	$	4,837	$	1,439	$	-6,621	$	7,522
Three Months Ended June 30, 2013
Operating revenues	$	96,846	$	30,042	$	1,400	$	-	$	-	$	128,288
Interdepartmental revenues		129		2,816		10,691		-		-13,636		-
Total operating revenues		96,975		32,858		12,091		-		-13,636		128,288
Depreciation and amortization		-6,314		-1,435		-1,781		-		-		-9,530
Other operating expenses*		-81,579		-30,130		-3,509		-		13,636		-101,582
Operating income*		9,082		1,293		6,801		-		-		17,176
Other (deductions) income, net*		319		-233		-		1,382		-		1,468
Interest expense, net		-2,315		-759		-1,605		-		-		-4,679
Net income		7,086		301		5,196		1,382		-		13,965
Less: Net income attributable to
noncontrolling interest, net of tax		-		-		-		-		-6,860		-6,860
Net income attributable to MGE	$	7,086	$	301	$	5,196	$	1,382	$	-6,860	$	7,105
Six Months Ended June 30, 2014
Operating revenues	$	195,560	$	141,941	$	1,530	$	-	$	-	$	339,031
Interdepartmental revenues		234		5,506		21,343		-		-27,083		-
Total operating revenues		195,794		147,447		22,873		-		-27,083		339,031
Depreciation and amortization		-12,978		-3,125		-3,689		-		-		-19,792
Other operating expenses*		-163,211		-130,638		-6,484		-		27,083		-273,250
Operating income*		19,605		13,684		12,700		-		-		45,989
Other (deductions) income, net*		2,517		-151		-		2,922		-		5,288
Interest expense, net		-4,739		-1,621		-3,131		-		-		-9,491
Net income		17,383		11,912		9,569		2,922		-		41,786
Less: Net income attributable to
noncontrolling interest, net of tax		-		-		-		-		-13,131		-13,131
Net income attributable to MGE	$	17,383	$	11,912	$	9,569	$	2,922	$	-13,131	$	28,655
Six Months Ended June 30, 2013
Operating revenues	$	190,340	$	102,509	$	2,676	$	-	$	-	$	295,525
Interdepartmental revenues		238		7,692		21,264		-		-29,194		-
Total operating revenues		190,578		110,201		23,940		-		-29,194		295,525
Depreciation and amortization		-12,714		-2,860		-3,580		-		-		-19,154
Other operating expenses*		-160,085		-96,598		-6,803		-		29,194		-234,292
Operating income*		17,779		10,743		13,557		-		-		42,079
Other (deductions) income, net*		1,042		-29		-		2,807		-		3,820
Interest expense, net		-4,719		-1,437		-3,218		-		-		-9,374
Net income		14,102		9,277		10,339		2,807		-		36,525
Less: Net income attributable to
noncontrolling interest, net of tax		-		-		-		-		-13,686		-13,686
Net income attributable to MGE	$	14,102	$	9,277	$	10,339	$	2,807	$	-13,686	$	22,839
*Amounts are shown net of the related tax expense, consistent with the presentation on the consolidated MGE Income Statement.
The following table shows segment information for MGE Energy's and MGE's assets and capital expenditures:
		Utility							Consolidated
(In thousands)MGE Energy		Electric		Gas		Assets not Allocated			Nonregulated Energy		Transmission Investment		All Others		Consolidation/ Elimination Entries		Total
Assets:
30-Jun-14	$	915,507	$	247,229	$	31,187		$	286,855	$	66,617	$	438,134	$	-388,566	$	1,596,963
31-Dec-13		899,257		265,694		19,853			288,116		64,504		431,436		-389,800		1,579,060
Capital Expenditures:
Six Months Ended June 30, 2014	$	34,133	$	7,289	$	-		$	850	$	-	$	-	$	-	$	42,272
Year ended Dec. 31, 2013		100,146		15,554		-			3,347		-		-		-		119,047
		Utility							Consolidated
(In thousands)MGE		Electric		Gas		Assets not Allocated			Nonregulated Energy		Transmission Investment		Elimination Entries		Total
Assets:
30-Jun-14	$	915,507	$	247,229	$	31,187		$	286,805	$	66,617	$	-6,756	$	1,540,589
31-Dec-13		899,257		265,694		19,853			288,066		64,504		-6,731		1,530,643
Capital Expenditures:
Six Months Ended June 30, 2014	$	34,133	$	7,289	$	-		$	850	$	-	$	-	$	42,272
Year ended Dec. 31, 2013		100,146		15,554		-			3,347		-		-		119,047

Significant_Accounting_Policie

Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2014
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 guidance. MGE is considered the primary beneficiary of these entities as a result of contractual agreements. As a result, MGE has consolidated MGE Power Elm Road and MGE Power West Campus.
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.
Investments - ATC	'
	MGE Transco has accounted for its investment in ATC under the equity method of accounting.
Share-based Compensation	'
	Under MGE Energy's Performance Unit Plan, 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 set performance period.
	In addition to units granted in 2009 through 2013, on February 21, 2014, 21,991 units were granted based on the MGE Energy closing stock price as of that date. These units are subject to a five-year graded vesting schedule and have been adjusted to reflect the three-for-two stock split declared December 20, 2013. On the grant date, MGE Energy and MGE measure the cost of the employee services received in exchange for a performance unit award based on the current market value of MGE Energy common stock. The fair value of the awards has been subsequently re-measured at June 30, 2014, as required by applicable accounting standards. Changes in fair value have been recognized as compensation cost. Since this amount is re-measured quarterly throughout the vesting period, the compensation cost is subject to variability.
	For nonretirement eligible employees, stock based compensation costs are accrued and recognized using the graded vesting method. Compensation cost for retirement eligible employees or employees that will become retirement eligible during the vesting schedule are recognized on an abridged horizon.
	In December 2013, a Director Incentive Plan was approved for the non-employee members of the Board of Directors. This plan is similar to MGE Energy's Performance Unit Plan for eligible employees described above. Under the plan, a non-employee director can 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 payments, at the end of the set performance period. The units are subject to a three-year graded vesting schedule. In January 2014, unit awards of 4,683 (post-split) were granted to the non-employee Directors. For accounting purposes, the awards will be measured similarly to the employee unit awards.
Chattel Paper Agreement	'
	MGE makes available to qualifying customers a financing program for the purchase and installation of energy-related equipment that will provide more efficient use of utility service at the customer's property. MGE is party to a chattel paper purchase agreement with a financial institution under which it can sell or finance an undivided interest with recourse, in up to $10.0 million of the financing program receivables, until July 31, 2015.
	MGE retains the servicing responsibility for these receivables.
	MGE accounts for servicing rights under the amortization method. Initial determination of the servicing asset fair value is based on the present value of the estimated future cash flows. The discount rate is based on the PSCW authorized weighted cost of capital.
	MGE would be required to perform under its guarantee if a customer defaulted on its loan. The energy-related equipment installed at the customer sites is used to secure the customer loans. The loan balances outstanding at June 30, 2014, approximate the fair value of the energy-related equipment acting as collateral. The length of the MGE guarantee to the financial institution varies from one to ten years depending on the term of the underlying customer loan.
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 and gas revenues. To the extent that these contracts are derivatives, MGE assesses whether or not the normal purchases or normal sales exclusion applies. For contracts to which this exclusion cannot be applied, MGE Energy and MGE recognize such derivatives in the consolidated balance sheets at fair value. The majority of MGE's derivative activities are conducted 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 can 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. 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 rates 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 agreement as well as the netting of collateral. For financial statement purposes, MGE Energy and MGE have netted instruments with the same counterparty under a master netting agreement as well as the netting of collateral.
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 most recent base rate proceedings. Any over/under recovery of the actual costs is determined on an annual basis and will be adjusted 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, less 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 return 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 that order.
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 standard clarifies that fair value should be based on the assumptions market participants would use when pricing the asset or liability including assumptions about risk. The standard 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 prices 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 model-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.
	At June 30, 2014 and December 31, 2013, the carrying amount of cash and cash equivalents approximates fair market value due to the short maturity of those investments and obligations. The estimated fair market value of MGE Energy's and MGE's long-term debt is based on quoted market prices for similar financial instruments at June 30, 2014 and December 31, 2013. Since long-term debt is not traded in an active market, it is classified as Level 2.
	Investments include exchange-traded investment securities valued using quoted prices on active exchanges and are therefore classified as Level 1.
	Derivatives include exchange-traded derivative contracts, over-the-counter transactions, a ten-year purchased power agreement, and FTRs. Most exchange-traded derivative contracts are valued based on unadjusted quoted prices in active markets and are therefore classified 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 classified as Level 3. Transactions done with an over-the-counter party are on inactive markets and are therefore considered unobservable and 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 similar instruments in a closed market with limited data available and are therefore classified as Level 3.
	The ten-year purchased power agreement (see Footnote 9) 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 judgment and estimation. Future energy prices are based on a forward power pricing curve using exchange-traded contracts in the electric futures market, where such exchange-traded contracts exist, and upon calculations based on forward gas prices, where such exchange-traded contracts do not exist. A basis adjustment is applied to the market energy price to reflect the price differential between the market price delivery point and the counterparty 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. If 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 determined 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 assumptions 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.
	This model is prepared by members of MGE's Energy Accounting group. It is reviewed on a quarterly basis by management in Energy Supply and Finance to review the assumptions, inputs, and fair value measurements.
	The following table presents the significant unobservable inputs used in the pricing model.
		Significant Unobservable Inputs	Model Input
		Basis adjustment:
		On peak	96.90%
		Off peak	94.20%
		Counterparty fuel mix:
		Internal generation	50% - 70%
		Purchased power	50% - 30%
	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 of MGE Energy and MGE. The notional investments earn interest based upon the semiannual rate of U.S. Treasury Bills having a 26 week 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.
New Accounting Pronouncements Disclosure	'
	New Accounting Pronouncements - MGE Energy and MGE.
	a. Obligations Resulting from Joint and Several Liability Arrangements for Which the Total Amount of the Obligation is Fixed at the Reporting Date.
	In February 2013, the FASB issued authoritative guidance within the Codification's Balance Sheet topic that provides guidance on the recognition, measurement, and disclosure of obligations resulting from joint and several liability arrangements for which the total amount of the obligation is fixed at the reporting date. This authoritative guidance became effective January 1, 2014. The authoritative guidance did not have a financial or disclosure impact.
	b. Presentation of an Unrecognized Tax Benefit.
	In July 2013, the FASB issued authoritative guidance within the Codification's Income Statement topic that provides guidance on the presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. The authoritative guidance was issued to eliminate diversity in practice by providing guidance on the presentation of unrecognized tax benefits. This authoritative guidance became effective January 1, 2014. The authoritative guidance will not have a financial statement or disclosure impact, unless MGE Energy or its subsidiaries are in a net operating loss position. MGE Energy or its subsidiaries are currently not in a net operating loss position.
	c. Revenue from Contracts with Customers.
	In May 2014, the FASB issued authoritative guidance within the Codification's Revenue Recognition topic that provides guidance on the recognition, measurement, and disclosure of revenue from contracts with customers. This authoritative guidance will become effective January 1, 2017. MGE Energy and MGE are currently assessing the impact this pronouncement will have on their financial statements.
	d. Transfers and Servicing Assets.
	In June 2014, the FASB issued authoritative guidance within the Codification's Transfers and Servicing topic that provides guidance on the accounting and disclosures for repurchase-to-maturity transactions, securities lending transactions, and repurchase financings. This authoritative guidance will become effective January 1, 2015. MGE Energy and MGE are currently assessing the impact this pronouncement will have on their financial statements.

Investment_in_ATC_Tables

Investment in ATC (Tables)	6 Months Ended
	Jun. 30, 2014
Equity Method Investments and Joint Ventures [Abstract]	'
ATC's Summarized Financial Data	'
	For the six months ended June 30, 2014 and 2013, MGE Transco recorded the following:
				Six Months Ended
				June 30,
		(In thousands)		2014		2013
		Equity in earnings from investment in ATC	$	4,883	$	4,705
		Dividends received from ATC		3,835		3,638
		Capital contributions to ATC		1,065		710
	ATC's summarized financial data for the three and six months ended June 30, 2014 and 2013, is as follows:
				Three Months Ended				Six Months Ended
				June 30,				June 30,
		(In thousands)		2014		2013		2014		2013
		Operating revenues	$	159,990	$	152,128	$	323,327	$	303,865
		Operating expenses		-74,405		-69,875		-153,028		-139,645
		Other income (expense), net		322		116		710		-332
		Interest expense, net		-22,242		-21,052		-44,238		-42,096
		Earnings before members' income taxes	$	63,665	$	61,317	$	126,771	$	121,792

Pension_and_Other_Postretireme1

Pension and Other Postretirement Plans (Tables)	6 Months Ended
	Jun. 30, 2014
Compensation and Retirement Disclosure [Abstract]	'
Schedule of Net Periodic Benefit Costs	'
	The following table presents the components of MGE Energy's and MGE's net periodic benefit costs recognized for the three and six months ended June 30, 2014 and 2013. A portion of the net periodic benefit cost is capitalized within the consolidated balance sheets.
				Three Months Ended				Six Months Ended
				June 30,				June 30,
		(In thousands)		2014		2013		2014		2013
		Pension Benefits
		Components of net periodic (benefit) cost:
		Service cost	$	1,589	$	1,911	$	3,073	$	3,840
		Interest cost		3,483		3,157		6,735		6,343
		Expected return on assets		-5,656		-4,733		-10,935		-9,509
		Amortization of:
		Prior service (benefit) cost		53		79		102		158
		Actuarial loss		186		1,997		358		4,012
		Net periodic (benefit) cost	$	-345	$	2,411	$	-667	$	4,844
		Postretirement Benefits
		Components of net periodic (benefit) cost:
		Service cost	$	152	$	591	$	482	$	1,187
		Interest cost		356		962		1,127		1,932
		Expected return on assets		-301		-540		-955		-1,084
		Amortization of:
		Transition obligation		-		1		1		2
		Prior service (benefit) cost		-307		27		-974		55
		Actuarial loss		17		309		57		620
		Net periodic (benefit) cost	$	-83	$	1,350	$	-262	$	2,712

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Chattel Paper Agreement, Fiscal Year Maturity Schedule	'
	Principal payments for the remainder of 2014 and the next four years on the loans are:
		(In thousands)		2014		2015		2016		2017		2018
		Chattel Paper	$	262	$	914	$	834	$	431	$	374
Purchase Contracts, Fiscal Year Maturity Schedule	'
	As of June 30, 2014, the future commitments related to these purchase contracts were as follows:
		(In thousands)		2014		2015		2016		2017		2018
		Natural gas supply(a)	$	17,911	$	16,840	$	-	$	-	$	-
		Purchase power(b)		50,569		49,086		49,757		50,257		51,279
		Other		17,111		-		-		-		-
			$	85,591	$	65,926	$	49,757	$	50,257	$	51,279
	(a) These commitments include market-based pricing. Management expects to recover these costs in future customer rates.
	(b) MGE has several purchase power agreements to help meet future electric supply requirements. Management expects to recover these costs in future customer rates.

Derivative_and_Hedging_Instrum1

Derivative and Hedging Instruments (Tables)	6 Months Ended
	Jun. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Gross Notional Volume of Open Derivatives	'
	The gross notional volume of open derivatives is as follows:
			30-Jun-14		31-Dec-13
		Commodity derivative contracts	431,510 MWh		458,660 MWh
		Commodity derivative contracts	4,382,500 Dth		3,750,000 Dth
		FTRs	4,597 MW		1,984 MW
Fair Value of Derivative Instruments on the Balance Sheet	'
	The following table summarizes the fair value of the derivative instruments on the consolidated balance sheet. 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 agreement as well as the netting of collateral. For financial statement purposes, MGE Energy and MGE have netted instruments with the same counterparty under a master netting agreement as well as the netting of collateral.
			Asset Derivatives				Liability Derivatives
	(In thousands)		Balance Sheet Location		Fair Value		Balance Sheet Location		Fair Value
	30-Jun-14
	Commodity derivative contracts		Other current assets	$	1,970		Derivative liability (current)	$	225
	Commodity derivative contracts		Other deferred charges		101		Derivative liability (long-term)		49
	FTRs		Other current assets		1,139		Derivative liability (current)		-
	Ten-year PPA		N/A		N/A		Derivative liability (current)		6,300
	Ten-year PPA		N/A		N/A		Derivative liability (long-term)		45,490
	31-Dec-13
	Commodity derivative contracts		Other current assets	$	1,356		Derivative liability (current)	$	51
	Commodity derivative contracts		Other deferred charges		167		Derivative liability (long-term)		48
	FTRs		Other current assets		363		Derivative liability (current)		-
	Ten-year PPA		N/A		N/A		Derivative liability (current)		7,750
	Ten-year PPA		N/A		N/A		Derivative liability (long-term)		57,930
Offsetting Assets	'
	The following tables show the effect of netting arrangements for recognized derivative assets and liabilities that are subject to a master netting arrangement or similar arrangement on the balance sheet.
		Offsetting of Derivative Assets
		(In thousands)		Gross amounts		Gross amounts offset in balance sheet		Collateral posted against derivative positions		Net amount presented in balance sheet
		30-Jun-14
		Commodity derivative contracts	$	2,071	$	-274	$	-292	$	1,505
		FTRs		1,139		-		-		1,139
		31-Dec-13
		Commodity derivative contracts	$	1,523	$	-99	$	-175	$	1,249
		FTRs		363		-		-		363
Offsetting Liabilities	'
		Offsetting of Derivative Liabilities
		(In thousands)		Gross amounts		Gross amounts offset in balance sheet		Collateral posted against derivative positions		Net amount presented in balance sheet
		30-Jun-14
		Commodity derivative contracts	$	274	$	-274	$	-	$	-
		Ten-year PPA		51,790		-		-		51,790
		31-Dec-13
		Commodity derivative contracts	$	99	$	-99	$	-	$	-
		Ten-year PPA		65,680		-		-		65,680
Derivative Gains and Losses in Balance Sheet	'
	The following tables summarize the unrealized and realized gains (losses) related to the derivative instruments on the consolidated balance sheet at June 30, 2014 and 2013, and the consolidated income statement for the three and six months ended June 30, 2014 and 2013.
			2014					2013
	(In thousands)		Current and long-term regulatory asset		Other current assets			Current and long-term regulatory asset		Other current assets
	Three Months Ended June 30:
	Balance at April 1,	$	58,213	$	351		$	69,197	$	259
	Change in unrealized gain		-9,817		-			-1,963		-
	Realized gain (loss) reclassified to a deferred
	account		-101		101			-388		388
	Realized gain (loss) reclassified to income
	statement		559		224			-197		11
	Balance at June 30,	$	48,854	$	676		$	66,649	$	658
	Six Months Ended June 30:
	Balance at January 1,	$	63,893	$	411		$	72,329	$	574
	Change in unrealized gain		-23,418		-			-3,660		-
	Realized gain (loss) reclassified to a deferred
	account		1,434		-1,434			-678		678
	Realized gain (loss) reclassified to income
	statement		6,945		1,699			-1,342		-594
	Balance at June 30,	$	48,854	$	676		$	66,649	$	658
Derivative Gains and Losses in Income Statement	'
			Realized losses (gains)
		(In thousands)		Fuel for electric generation/ purchased power		Cost of gas sold
		Three Months Ended June 30, 2014:
		Commodity derivative contracts	$	-1,061	$	-128
		FTRs		-196		-
		Ten-year PPA		602		-
		Three Months Ended June 30, 2013:
		Commodity derivative contracts	$	-538	$	-
		FTRs		-351		-
		Ten-year PPA		1,075		-
		Six Months Ended June 30, 2014:
		Commodity derivative contracts	$	-5,856	$	-1,349
		FTRs		-832		-
		Ten-year PPA		-607		-
		Six Months Ended June 30, 2013:
		Commodity derivative contracts	$	-516	$	608
		FTRs		-509		-
		Ten-year PPA		2,353		-

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2014
Fair Value Disclosures [Abstract]	'
Estimated Fair Market Value of Financial Instruments	'
	The estimated fair market value of MGE Energy's and MGE's financial instruments are as follows:
				30-Jun-14					31-Dec-13
		(In thousands)		Carrying Amount		Fair Value			Carrying Amount		Fair Value
		MGE Energy
		Assets:
		Cash and cash equivalents	$	87,911	$	87,911		$	68,813	$	68,813
		Liabilities:
		Long-term debt*		401,751		444,752			403,793		432,010
		MGE
		Assets:
		Cash and cash equivalents	$	26,284	$	26,284		$	14,808	$	14,808
		Liabilities:
		Long-term debt*		401,751		444,752			403,793		432,010
		*Includes long-term debt due within one year.
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 recurring basis for MGE Energy and MGE.
				Fair Value as of June 30, 2014
		(In thousands)		Total		Level 1		Level 2		Level 3
		MGE Energy
		Assets:
		Exchange-traded investments	$	727	$	727	$	-	$	-
		Total Assets	$	727	$	727	$	-	$	-
		Liabilities:
		Derivatives, net(a)	$	48,854	$	-495	$	-	$	49,349
		Deferred compensation		2,591		-		2,591		-
		Total Liabilities	$	51,445	$	-495	$	2,591	$	49,349
		MGE
		Assets:
		Exchange-traded investments	$	268	$	268	$	-	$	-
		Total Assets	$	268	$	268	$	-	$	-
		Liabilities:
		Derivatives, net(a)	$	48,854	$	-495	$	-	$	49,349
		Deferred compensation		2,591		-		2,591		-
		Total Liabilities	$	51,445	$	-495	$	2,591	$	49,349
				Fair Value as of December 31, 2013
		(In thousands)		Total		Level 1		Level 2		Level 3
		MGE Energy
		Assets:
		Exchange-traded investments	$	792	$	792	$	-	$	-
		Total Assets	$	792	$	792	$	-	$	-
		Liabilities:
		Derivatives, net(a)	$	63,893	$	-735	$	-	$	64,628
		Deferred compensation		2,364		-		2,364		-
		Total Liabilities	$	66,257	$	-735	$	2,364	$	64,628
		MGE
		Assets:
		Exchange-traded investments	$	431	$	431	$	-	$	-
		Total Assets	$	431	$	431	$	-	$	-
		Liabilities:
		Derivatives, net(a)	$	63,893	$	-735	$	-	$	64,628
		Deferred compensation		2,364		-		2,364		-
		Total Liabilities	$	66,257	$	-735	$	2,364	$	64,628
		(a) These amounts are shown gross and exclude $0.3 million and $0.2 million of collateral that was
		posted against derivative positions with counterparties as of June 30, 2014 and
		December 31, 2013, respectively.
Significant Unobservable Inputs	'
	The following table presents the significant unobservable inputs used in the pricing model.
		Significant Unobservable Inputs		Model Input
		Basis adjustment:
		On peak		96.90%
		Off peak		94.20%
		Counterparty fuel mix:
		Internal generation		50% - 70%
		Purchased power		50% - 30%
Changes in Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis	'
	The following table summarizes the changes in Level 3 assets and liabilities measured at fair value on a recurring basis for both MGE Energy and MGE.
			Three Months Ended				Six Months Ended
			June 30,				June 30,
	(In thousands)		2014		2013		2014		2013
	Beginning balance,	$	-58,797	$	-69,598	$	-64,628	$	-72,346
	Realized and unrealized gains (losses):
	Included in regulatory liabilities (assets)		9,448		2,743		15,279		5,490
	Included in other comprehensive income		-		-		-		-
	Included in earnings		651		-44		7,218		-1,351
	Included in current assets		-185		-123		-185		-123
	Purchases		6,828		6,162		13,634		11,724
	Sales		-		-		-60		-2
	Issuances		-		-		-		-
	Settlements		-7,294		-5,996		-20,607		-10,248
	Transfers in and/or out of Level 3		-		-		-		-
	Balance as of June 30,	$	-49,349	$	-66,856	$	-49,349	$	-66,856
	Total gains (losses) included in earnings attributed to
	the change in unrealized gains (losses) related to
	assets and liabilities held at June 30,(b)	$	-	$	-	$	-	$	-
	(b) MGE's exchange-traded derivative contracts, over-the-counter party transactions, ten-year purchased power agreement, and FTRs are subject to regulatory deferral. These derivatives are therefore marked to fair value and are offset 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) included in income for Level 3 assets and liabilities measured at fair value on a recurring basis for both MGE Energy and MGE (b).
				Three Months Ended				Six Months Ended
				June 30,				June 30,
		(In thousands)		2014		2013		2014		2013
		Purchased Power Expense	$	651	$	-44	$	7,218	$	-1,351
	(b) MGE's exchange-traded derivative contracts, over-the-counter party transactions, ten-year purchased power agreement, and FTRs are subject to regulatory deferral. These derivatives are therefore marked to fair value and are offset with a corresponding regulatory asset or liability.

Segment_Information_Tables

Segment Information (Tables)	6 Months Ended
	Jun. 30, 2014
Segment Reporting [Abstract]	'
Segment Information	'
	The following tables show segment information for MGE Energy's operations for the indicated periods:
	(In thousands)MGE Energy		Electric		Gas		Non- Regulated Energy		Transmission Investment		All Others		Consolidation/ Elimination Entries		Consolidated Total
	Three Months Ended June 30, 2014
	Operating revenues	$	96,697	$	31,218	$	850	$	-	$	-	$	-	$	128,765
	Interdepartmental revenues		127		1,892		10,673		-		-		-12,692		-
	Total operating revenues		96,824		33,110		11,523		-		-		-12,692		128,765
	Depreciation and amortization		-6,641		-1,562		-1,855		-		-11		-		-10,069
	Other operating expenses		-76,812		-29,865		-30		-		-240		12,692		-94,255
	Operating income (loss)		13,371		1,683		9,638		-		-251		-		24,441
	Other (deductions) income, net		1,036		-17		-		2,402		127		-		3,548
	Interest (expense) income, net		-2,534		-817		-1,559		-		42		-		-4,868
	Income (loss) before taxes		11,873		849		8,079		2,402		-82		-		23,121
	Income tax (provision) benefit		-4,491		-364		-3,242		-963		26		-		-9,034
	Net income (loss)	$	7,382	$	485	$	4,837	$	1,439	$	-56	$	-	$	14,087
	Three Months Ended June 30, 2013
	Operating revenues	$	96,846	$	30,042	$	1,400	$	-	$	-	$	-	$	128,288
	Interdepartmental revenues		129		2,816		10,691		-		-		-13,636		-
	Total operating revenues		96,975		32,858		12,091		-		-		-13,636		128,288
	Depreciation and amortization		-6,314		-1,435		-1,781		-		-		-		-9,530
	Other operating expenses		-78,051		-29,572		-26		-		-248		13,636		-94,261
	Operating income (loss)		12,610		1,851		10,284		-		-248		-		24,497
	Other (deductions) income, net		485		-185		-		2,309		102		-		2,711
	Interest (expense) income, net		-2,315		-759		-1,605		-		22		-		-4,657
	Income (loss) before taxes		10,780		907		8,679		2,309		-124		-		22,551
	Income tax (provision) benefit		-3,694		-606		-3,483		-927		50		-		-8,660
	Net income (loss)	$	7,086	$	301	$	5,196	$	1,382	$	-74	$	-	$	13,891
	Six Months Ended June 30, 2014
	Operating revenues	$	195,549	$	141,931	$	1,530	$	-	$	-	$	-	$	339,010
	Interdepartmental revenues		245		5,516		21,343		-		-		-27,104		-
	Total operating revenues		195,794		147,447		22,873		-		-		-27,104		339,010
	Depreciation and amortization		-12,978		-3,125		-3,689		-		-23		-		-19,815
	Other operating expenses		-154,713		-122,708		-70		-		-396		27,104		-250,783
	Operating income (loss)		28,103		21,614		19,114		-		-419		-		68,412
	Other (deductions) income, net		2,863		-52		-		4,883		406		-		8,100
	Interest (expense) income, net		-4,739		-1,621		-3,131		-		82		-		-9,409
	Income before taxes		26,227		19,941		15,983		4,883		69		-		67,103
	Income tax provision		-8,844		-8,029		-6,414		-1,961		-51		-		-25,299
	Net income	$	17,383	$	11,912	$	9,569	$	2,922	$	18	$	-	$	41,804
	Six Months Ended June 30, 2013
	Operating revenues	$	190,340	$	102,509	$	2,676	$	-	$	-	$	-	$	295,525
	Interdepartmental revenues		238		7,692		21,264		-		-		-29,194		-
	Total operating revenues		190,578		110,201		23,940		-		-		-29,194		295,525
	Depreciation and amortization		-12,714		-2,860		-3,580		-		-		-		-19,154
	Other operating expenses		-152,976		-90,009		-63		-		-392		29,194		-214,246
	Operating income (loss)		24,888		17,332		20,297		-		-392		-		62,125
	Other (deductions) income, net		1,060		-23		-		4,705		278		-		6,020
	Interest (expense) income, net		-4,719		-1,437		-3,218		-		42		-		-9,332
	Income (loss) before taxes		21,229		15,872		17,079		4,705		-72		-		58,813
	Income tax (provision) benefit		-7,127		-6,595		-6,740		-1,898		22		-		-22,338
	Net income (loss)	$	14,102	$	9,277	$	10,339	$	2,807	$	-50	$	-	$	36,475
	The following tables show segment information for MGE's operations for the indicated periods:
	(In thousands)MGE		Electric		Gas		Non- Regulated Energy		Transmission Investment		Consolidation/ Elimination Entries		Consolidated Total
	Three Months Ended June 30, 2014
	Operating revenues	$	96,702	$	31,223	$	850	$	-	$	-	$	128,775
	Interdepartmental revenues		122		1,887		10,673		-		-12,682		-
	Total operating revenues		96,824		33,110		11,523		-		-12,682		128,775
	Depreciation and amortization		-6,641		-1,562		-1,855		-		-		-10,058
	Other operating expenses*		-81,165		-30,188		-3,272		-		12,682		-101,943
	Operating income*		9,018		1,360		6,396		-		-		16,774
	Other (deductions) income, net*		898		-58		-		1,439		-		2,279
	Interest expense, net		-2,534		-817		-1,559		-		-		-4,910
	Net income		7,382		485		4,837		1,439		-		14,143
	Less: Net income attributable to
noncontrolling interest, net of tax		-		-		-		-		-6,621		-6,621
Net income attributable to MGE	$	7,382	$	485	$	4,837	$	1,439	$	-6,621	$	7,522
Three Months Ended June 30, 2013
Operating revenues	$	96,846	$	30,042	$	1,400	$	-	$	-	$	128,288
Interdepartmental revenues		129		2,816		10,691		-		-13,636		-
Total operating revenues		96,975		32,858		12,091		-		-13,636		128,288
Depreciation and amortization		-6,314		-1,435		-1,781		-		-		-9,530
Other operating expenses*		-81,579		-30,130		-3,509		-		13,636		-101,582
Operating income*		9,082		1,293		6,801		-		-		17,176
Other (deductions) income, net*		319		-233		-		1,382		-		1,468
Interest expense, net		-2,315		-759		-1,605		-		-		-4,679
Net income		7,086		301		5,196		1,382		-		13,965
Less: Net income attributable to
noncontrolling interest, net of tax		-		-		-		-		-6,860		-6,860
Net income attributable to MGE	$	7,086	$	301	$	5,196	$	1,382	$	-6,860	$	7,105
Six Months Ended June 30, 2014
Operating revenues	$	195,560	$	141,941	$	1,530	$	-	$	-	$	339,031
Interdepartmental revenues		234		5,506		21,343		-		-27,083		-
Total operating revenues		195,794		147,447		22,873		-		-27,083		339,031
Depreciation and amortization		-12,978		-3,125		-3,689		-		-		-19,792
Other operating expenses*		-163,211		-130,638		-6,484		-		27,083		-273,250
Operating income*		19,605		13,684		12,700		-		-		45,989
Other (deductions) income, net*		2,517		-151		-		2,922		-		5,288
Interest expense, net		-4,739		-1,621		-3,131		-		-		-9,491
Net income		17,383		11,912		9,569		2,922		-		41,786
Less: Net income attributable to
noncontrolling interest, net of tax		-		-		-		-		-13,131		-13,131
Net income attributable to MGE	$	17,383	$	11,912	$	9,569	$	2,922	$	-13,131	$	28,655
Six Months Ended June 30, 2013
Operating revenues	$	190,340	$	102,509	$	2,676	$	-	$	-	$	295,525
Interdepartmental revenues		238		7,692		21,264		-		-29,194		-
Total operating revenues		190,578		110,201		23,940		-		-29,194		295,525
Depreciation and amortization		-12,714		-2,860		-3,580		-		-		-19,154
Other operating expenses*		-160,085		-96,598		-6,803		-		29,194		-234,292
Operating income*		17,779		10,743		13,557		-		-		42,079
Other (deductions) income, net*		1,042		-29		-		2,807		-		3,820
Interest expense, net		-4,719		-1,437		-3,218		-		-		-9,374
Net income		14,102		9,277		10,339		2,807		-		36,525
Less: Net income attributable to
noncontrolling interest, net of tax		-		-		-		-		-13,686		-13,686
Net income attributable to MGE	$	14,102	$	9,277	$	10,339	$	2,807	$	-13,686	$	22,839
*Amounts are shown net of the related tax expense, consistent with the presentation on the consolidated MGE Income Statement.
The following table shows segment information for MGE Energy's and MGE's assets and capital expenditures:
		Utility							Consolidated
(In thousands)MGE Energy		Electric		Gas		Assets not Allocated			Nonregulated Energy		Transmission Investment		All Others		Consolidation/ Elimination Entries		Total
Assets:
30-Jun-14	$	915,507	$	247,229	$	31,187		$	286,855	$	66,617	$	438,134	$	-388,566	$	1,596,963
31-Dec-13		899,257		265,694		19,853			288,116		64,504		431,436		-389,800		1,579,060
Capital Expenditures:
Six Months Ended June 30, 2014	$	34,133	$	7,289	$	-		$	850	$	-	$	-	$	-	$	42,272
Year ended Dec. 31, 2013		100,146		15,554		-			3,347		-		-		-		119,047
		Utility							Consolidated
(In thousands)MGE		Electric		Gas		Assets not Allocated			Nonregulated Energy		Transmission Investment		Elimination Entries		Total
Assets:
30-Jun-14	$	915,507	$	247,229	$	31,187		$	286,805	$	66,617	$	-6,756	$	1,540,589
31-Dec-13		899,257		265,694		19,853			288,066		64,504		-6,731		1,530,643
Capital Expenditures:
Six Months Ended June 30, 2014	$	34,133	$	7,289	$	-		$	850	$	-	$	-	$	42,272
Year ended Dec. 31, 2013		100,146		15,554		-			3,347		-		-		119,047

Equity_and_Financing_Arrangeme1

Equity and Financing Arrangements (Details) (USD $)	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Common Stock [Abstract]	'	'
Common stock issued during period	0	0
Dilutive Shares Calculation [Abstract]	'	'
Dilutive securities	$0	'

Investment_in_ATC_Details1

Investment in ATC (Details-1) (USD $)	6 Months Ended					0 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jul. 31, 2014
			MGE Transco [Member]	MGE Transco [Member]	MGE Transco [Member]	MGE Transco [Member]
			ATC [Member]	ATC [Member]	ATC [Member]	ATC [Member]
						Subsequent Event [Member]
Schedule Of Equity Method Investments [Line Items]	'	'	'	'	'	'
Equity earnings from investment	$4,883,000	$4,705,000	$4,883,000	$4,705,000	'	'
Dividend income from investment	3,835,000	3,638,000	3,835,000	3,638,000	'	'
Capital contributions to investment	1,225,000	950,000	1,065,000	710,000	'	400,000
Equity method investment	'	'	$66,600,000	'	$64,500,000	'

Investment_in_ATC_Details2

Investment in ATC (Details-2) (ATC [Member], USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
ATC [Member]	'	'	'	'
Schedule Of Equity Method Investments [Line Items]	'	'	'	'
Operating revenues	$159,990	$152,128	$323,327	$303,865
Operating expenses	-74,405	-69,875	-153,028	-139,645
Other income (expense), net	322	116	710	-332
Interest expense, net	-22,242	-21,052	-44,238	-42,096
Earnings before members' income taxes	$63,665	$61,317	$126,771	$121,792

Columbia_Environmental_Project1

Columbia Environmental Project Construction (Details) (USD $)

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

MGE [Member]

MGE [Member]

MGE [Member]

MGE [Member]

MGE [Member]

MGE [Member]

MGE [Member]

MGE [Member]

MGE [Member]

MGE [Member]

MGE [Member]

MGE [Member]

MGE [Member]

Columbia Units [Member]

Columbia Units [Member]

Columbia Units [Member]

Columbia Environmental Project [Member]

Columbia Environmental Project [Member]

Columbia Environmental Project [Member]

Columbia Environmental Project [Member]

Columbia Environmental Project [Member]

Columbia Environmental Project [Member]

Columbia Environmental Project, Unit 1 [Member]

Columbia Environmental Project, Unit 2 [Member]

WPL [Member]

WPSC [Member]

MGE [Member]

PSCW [Member]

PSCW [Member]

Jointly Owned Utility Plant Interests [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Jointly owned utility plant, ownership interest

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

46.20%

31.80%

22.00%

Property, plant, and equipment, total

$1,112,755,000

$1,018,809,000

$1,111,845,000

'

$1,111,845,000

'

$1,017,877,000

'

'

'

'

'

'

'

$82,200,000

'

'

'

Property, plant, and equipment, portion related to capital expenditures

'

'

'

'

'

'

'

'

'

'

'

'

'

'

76,900,000

'

'

'

Property, plant, and equipment, portion related to AFUDC

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5,300,000

'

'

'

Construction work in progress, portion related to capital expenditures

'

'

'

'

'

'

'

'

'

'

'

'

'

50,600,000

'

'

'

'

Construction work in progress, portion related to AFUDC

'

'

'

'

'

'

'

'

'

'

'

'

'

4,400,000

'

'

'

'

Contractual commitments

'

'

'

'

'

'

'

8,100,000

'

8,100,000

'

'

'

'

'

'

'

'

AFUDC - equity funds

'

'

$1,101,000

$730,000

$3,051,000

$1,326,000

'

$1,000,000

$600,000

$2,900,000

$1,100,000

'

'

'

'

'

'

'

Authorized AFUDC Rate

'

'

'

'

'

'

'

'

'

'

'

100.00%

50.00%

'

'

'

'

'

Authorized MGE rate of return

'

'

'

'

'

'

'

'

'

'

'

'

50.00%

'

'

'

'

'

Taxes_Details

Taxes (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Tax Disclosure [Line Items]	'	'	'	'
Effective income tax rate	39.10%	38.40%	37.70%	38.00%
MGE [Member]	'	'	'	'
Income Tax Disclosure [Line Items]	'	'	'	'
Effective income tax rate	39.10%	38.40%	37.70%	38.00%

Pension_and_Other_Postretireme2

Pension and Other Postretirement Plans (Details) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Pension Benefits [Member]	'	'	'	'
Components of net periodic (benefit) cost:	'	'	'	'
Service cost	$1,589	$1,911	$3,073	$3,840
Interest cost	3,483	3,157	6,735	6,343
Expected return on assets	-5,656	-4,733	-10,935	-9,509
Amortization of:	'	'	'	'
Prior service (benefit) cost	53	79	102	158
Actuarial loss	186	1,997	358	4,012
Net periodic (benefit) cost	-345	2,411	-667	4,844
Postretirement Benefits [Member]	'	'	'	'
Components of net periodic (benefit) cost:	'	'	'	'
Service cost	152	591	482	1,187
Interest cost	356	962	1,127	1,932
Expected return on assets	-301	-540	-955	-1,084
Amortization of:	'	'	'	'
Transition obligation	0	1	1	2
Prior service (benefit) cost	-307	27	-974	55
Actuarial loss	17	309	57	620
Net periodic (benefit) cost	($83)	$1,350	($262)	$2,712

Share_Based_Compensation_Detai

Share Based Compensation (Details) (Performance Units [Member], USD $)	6 Months Ended			0 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended
In Millions, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jan. 31, 2014	Feb. 21, 2014	Jun. 30, 2014	Jan. 31, 2014	Jun. 30, 2014
				Performance Unit Plan [Member]	Performance Unit Plan [Member]	Director Incentive Agreement [Member]	Director Incentive Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'
Awards granted during period (in units)	'	'	'	21,991	'	4,683	'
Award vesting period	'	'	'	'	'5 years	'	'3 years
Compensation expense	$1.10	$1	'	'	'	'	'
Cash payments distributed related to awards previously granted and now payable	'	'	1.2	'	'	'	'
Awards forfeited during period	0	0	'	'	'	'	'
Outstanding awards vested during period	$3.90	'	'	'	'	'	'

Commitments_and_Contingencies_1

Commitments and Contingencies (Details-1) (USD $)	6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 17, 2014
	Columbia Units [Member]	EPA [Member]
Public Utilities, General Disclosures [Line Items]	'	'
National average reduction of greenhouse gas emissions by the year 2030, percentage	'	30.00%
Columbia Commitments [Abstract]	'	'
Accrual for future environmental mitigation projects	$0.60	'
Envrionmental civil penalty expense	$0.20	'

Commitments_and_Contingencies_2

Commitments and Contingencies (Details-2) (Chattel Paper Agreement [Member], USD $)	6 Months Ended
	Jun. 30, 2014
Guarantor Obligations [Line Items]	'
Guarantor obligation, maximum financing receivable	10,000,000
Guarantor obligation, current carrying value	4,300,000
Servicing asset recognized	200,000
Guarantor Obligation, Fiscal Year Maturity [Abstract]	'
Guarantor obligation, 2014	262,000
Guarantor obligation, 2015	914,000
Guarantor obligation, 2016	834,000
Guarantor obligation, 2017	431,000
Guarantor obligation, 2018	374,000
Minimum [Member]	'
Guarantor Obligations [Line Items]	'
Guarantee to financial institution, term	'1 year
Maximum [Member]	'
Guarantor Obligations [Line Items]	'
Guarantee to financial institution, term	'10 years

Commitments_and_Contingencies_3

Commitments and Contingencies (Details-3) (USD $)	Jun. 30, 2014
In Thousands, unless otherwise specified
Operating expense purchase contracts [Abstract]	'
Purchase obligation, 2014	$85,591
Purchase obligation, 2015	65,926
Purchase obligation, 2016	49,757
Purchase obligation, 2017	50,257
Purchase obligation, 2018	51,279
Natual Gas, Supply [Member]	'
Operating expense purchase contracts [Abstract]	'
Purchase obligation, 2014	17,911	[1]
Purchase obligation, 2015	16,840	[1]
Purchase obligation, 2016	0	[1]
Purchase obligation, 2017	0	[1]
Purchase obligation, 2018	0	[1]
Purchase Power [Member]	'
Operating expense purchase contracts [Abstract]	'
Purchase obligation, 2014	50,569	[2]
Purchase obligation, 2015	49,086	[2]
Purchase obligation, 2016	49,757	[2]
Purchase obligation, 2017	50,257	[2]
Purchase obligation, 2018	51,279	[2]
Other [Member]	'
Operating expense purchase contracts [Abstract]	'
Purchase obligation, 2014	17,111
Purchase obligation, 2015	0
Purchase obligation, 2016	0
Purchase obligation, 2017	0
Purchase obligation, 2018	$0
[1]	These commitments include market-based pricing. Management expects to recover these costs in future customer rates.
[2]	MGE has several purchase power agreements to help meet future electric supply requirements. Management expects to recover these costs in future customer rates.

Derivative_and_Hedging_Instrum2

Derivative and Hedging Instruments (Details-1) (USD $)

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2012

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

In Thousands, unless otherwise specified

Other Current Assets [Member]

Other Current Assets [Member]

Other Current Assets [Member]

Other Current Assets [Member]

Other Current Assets [Member]

Other Current Assets [Member]

Commodity Contracts And Financial Transimission Rights [Member]

Commodity Contracts And Financial Transimission Rights [Member]

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Energy Related Commodity Contract [Member]

Financial Transmission Rights [Member]

Financial Transmission Rights [Member]

Financial Transmission Rights [Member]

Financial Transmission Rights [Member]

Financial Transmission Rights [Member]

Financial Transmission Rights [Member]

Ten-year PPA [Member]

Ten-year PPA [Member]

Ten-year PPA [Member]

Ten-year PPA [Member]

Ten-year PPA [Member]

Ten-year PPA [Member]

MWh

MWh

Other Current Assets [Member]

Other Current Assets [Member]

Other Deferred Charges [Member]

Other Deferred Charges [Member]

Derivative Liability (Current) [Member]

Derivative Liability (Current) [Member]

Derivative Liability (Long-term) [Member]

Derivative Liability (Long-term) [Member]

Cash Flow Hedging [Member]

MW

MW

Other Current Assets [Member]

Other Current Assets [Member]

Derivative Liability (Current) [Member]

Derivative Liability (Current) [Member]

Derivative Liability (Current) [Member]

Derivative Liability (Current) [Member]

Derivative Liability (Long-term) [Member]

Derivative Liability (Long-term) [Member]

Dth

Dth

Derivatives Fair Value [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum term of derivative hedging contract

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'4 years

'

'

'

'

'

'

'

'

'

'

'

'

Gross Notional Volume of Open Derivatives

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Notional amount, energy measure (in MWh)

'

'

'

'

'

'

'

'

431,510

458,660

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Notional amount, decatherm measure (in Dth)

'

'

'

'

'

'

'

'

4,382,500

3,750,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Notional amount, power measure (in MW)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4,597

1,984

'

'

'

'

'

'

'

'

'

'

Derivative fair values [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Derivative fair value, net

$676

$351

$411

$658

$259

$574

$2,900

$1,800

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

($51,800)

($65,700)

'

'

'

'

Derivative Asset, Fair Value, Gross Asset

'

'

'

'

'

'

'

'

2,071

1,523

1,970

1,356

101

167

'

'

'

'

'

1,139

363

1,139

363

'

'

'

'

'

'

'

'

Derivative Liability, Fair Value, Gross Liability

'

'

'

'

'

'

'

'

$274

$99

'

'

'

'

$225

$51

$49

$48

'

'

'

'

'

$0

$0

$51,790

$65,680

$6,300

$7,750

$45,490

$57,930

Derivative_and_Hedging_Instrum3

Derivative and Hedging Instruments (Details-2) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Offsetting Assets [Line Items]	'	'
Collateral posted against derivative positions	($300)	($200)
Commodity Derivative Contracts [Member]	'	'
Offsetting Assets [Line Items]	'	'
Gross amounts	2,071	1,523
Gross amounts offset in balance sheet	-274	-99
Collateral posted against derivative positions	-292	-175
Net amount presented in balance sheet	1,505	1,249
Financial Transmission Rights [Member]	'	'
Offsetting Assets [Line Items]	'	'
Gross amounts	1,139	363
Gross amounts offset in balance sheet	0	0
Collateral posted against derivative positions	0	0
Net amount presented in balance sheet	$1,139	$363

Derivative_and_Hedging_Instrum4

Derivative and Hedging Instruments (Details-3) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Commodity Derivative Contracts [Member]	'	'
Offsetting Liabilities [Line Items]	'	'
Gross amounts	$274	$99
Gross amounts offset in balance sheet	-274	-99
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	51,790	65,680
Gross amounts offset in balance sheet	0	0
Collateral posted against derivative positions	0	0
Net amount presented in balance sheet	$51,790	$65,680

Derivative_and_Hedging_Instrum5

Derivative and Hedging Instruments (Details-4) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Regulatory Asset [Member]	'	'	'	'
Change In Derivative Fair Value [Roll Forward]	'	'	'	'
Beginning balance,	$58,213	$69,197	$63,893	$72,329
Change in unrealized gain	-9,817	-1,963	-23,418	-3,660
Realized gain (loss) reclassified to a deferred account	-101	-388	1,434	-678
Realized gain (loss) reclassified to income statement	559	-197	6,945	-1,342
Ending balance,	48,854	66,649	48,854	66,649
Other Current Assets [Member]	'	'	'	'
Change In Derivative Fair Value [Roll Forward]	'	'	'	'
Beginning balance,	351	259	411	574
Change in unrealized gain	0	0	0	0
Realized gain (loss) reclassified to a deferred account	101	388	-1,434	678
Realized gain (loss) reclassified to income statement	224	11	1,699	-594
Ending balance,	$676	$658	$676	$658

Derivative_and_Hedging_Instrum6

Derivative and Hedging Instruments (Details-5) (USD $)

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

counterparty

counterparty

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Commodity Derivative Contracts [Member]

Financial Transmission Rights [Member]

Financial Transmission Rights [Member]

Financial Transmission Rights [Member]

Financial Transmission Rights [Member]

Financial Transmission Rights [Member]

Financial Transmission Rights [Member]

Financial Transmission Rights [Member]

Financial Transmission Rights [Member]

Purchased Power Agreement [Member]

Purchased Power Agreement [Member]

Purchased Power Agreement [Member]

Purchased Power Agreement [Member]

Purchased Power Agreement [Member]

Purchased Power Agreement [Member]

Purchased Power Agreement [Member]

Purchased Power Agreement [Member]

Purchased Power Agreement [Member]

Fuel For Electric Generation Purchased Power [Member]

Fuel For Electric Generation Purchased Power [Member]

Fuel For Electric Generation Purchased Power [Member]

Fuel For Electric Generation Purchased Power [Member]

Cost Of Gas Sold Expense [Member]

Cost Of Gas Sold Expense [Member]

Cost Of Gas Sold Expense [Member]

Cost Of Gas Sold Expense [Member]

Fuel For Electric Generation Purchased Power [Member]

Fuel For Electric Generation Purchased Power [Member]

Fuel For Electric Generation Purchased Power [Member]

Fuel For Electric Generation Purchased Power [Member]

Cost Of Gas Sold Expense [Member]

Cost Of Gas Sold Expense [Member]

Cost Of Gas Sold Expense [Member]

Cost Of Gas Sold Expense [Member]

Fuel For Electric Generation Purchased Power [Member]

Fuel For Electric Generation Purchased Power [Member]

Fuel For Electric Generation Purchased Power [Member]

Fuel For Electric Generation Purchased Power [Member]

Cost Of Gas Sold Expense [Member]

Cost Of Gas Sold Expense [Member]

Cost Of Gas Sold Expense [Member]

Cost Of Gas Sold Expense [Member]

Realized losses (gains) on income statement [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Realized losses (gains) on income statement

'

'

($1,061,000)

($538,000)

($5,856,000)

($516,000)

($128,000)

$0

($1,349,000)

$608,000

($196,000)

($351,000)

($832,000)

($509,000)

$0

$0

$0

$0

'

$602,000

$1,075,000

($607,000)

$2,353,000

$0

$0

$0

$0

Derivative collateral required to be posted for ten-year PPA [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Minimum collateral that may be required to be posted

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

20,000,000

'

'

'

'

'

'

'

'

Maximum collateral that may be required to be posted

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

40,000,000

'

'

'

'

'

'

'

'

Collateral posted

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$0

'

'

'

'

'

'

'

'

Counterparties in net liability position or default [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Counterparties in net liability position

0

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of counterparties in default

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Rate_Matters_Details

Rate Matters (Details) (PSCW [Member], USD $)	6 Months Ended		12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended		6 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014	Dec. 31, 2013	Dec. 31, 2015	Jun. 30, 2014	Dec. 31, 2013	Dec. 31, 2015
	Legal Entity Type of Counterparty [Domain]	MGE [Member]	MGE [Member]	Columbia Environmental Project [Member]	Columbia Environmental Project [Member]	Electric [Member]	Electric [Member]	Electric [Member]	Gas [Member]	Gas [Member]	Gas [Member]
				MGE [Member]	MGE [Member]	MGE [Member]	MGE [Member]	Proposed Future Rate Matters [Member]	MGE [Member]	MGE [Member]	Proposed Future Rate Matters [Member]
								MGE [Member]			MGE [Member]
Rate Proceedings [Abstract]	'	'	'	'	'	'	'	'	'	'	'
Proposed rate increase (decrease), percentage	'	'	'	'	'	'	'	2.80%	'	'	-2.30%
Authorized rate increase (decrease), percentage	'	'	'	'	'	0.00%	3.80%	'	0.00%	1.00%	'
Authorized rate increase (decrease), amount	'	'	'	'	'	$0	$14.90	'	$0	$1.60	'
Authorized AFUDC Rate	'	'	'	100.00%	50.00%	'	'	'	'	'	'
Return of electric fuel credit, total	'	6.2	'	'	'	'	'	'	'	'	'
Authorized return on equity, percentage	'	10.30%	10.30%	'	'	'	'	'	'	'	'
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%	'	'	'	'	'	'	'	'	'	'
Return of electric fuel credit, current period	'	$3.20	'	'	'	'	'	'	'	'	'

Fair_Value_of_Financial_Instru2

Fair Value of Financial Instruments (Details-1) (USD $)	Jun. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Carrying Amount [Member]	'		'
Assets:	'		'
Cash and cash equivalents	$87,911		$68,813
Liabilities:	'		'
Long-term debt	401,751	[1]	403,793	[1]
Fair Value [Member]	'		'
Assets:	'		'
Cash and cash equivalents	87,911		68,813
Liabilities:	'		'
Long-term debt	444,752	[1]	432,010	[1]
MGE [Member] | Carrying Amount [Member]	'		'
Assets:	'		'
Cash and cash equivalents	26,284		14,808
Liabilities:	'		'
Long-term debt	401,751	[1]	403,793	[1]
MGE [Member] | Fair Value [Member]	'		'
Assets:	'		'
Cash and cash equivalents	26,284		14,808
Liabilities:	'		'
Long-term debt	$444,752	[1]	$432,010	[1]
[1]	*Includes long-term debt due within one year.

Fair_Value_of_Financial_Instru3

Fair Value of Financial Instruments (Details-2) (USD $)	Jun. 30, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Liabilities:	'		'
Derivative asset, collateral offset	$300		$200
Recurring [Member]	'		'
Assets:	'		'
Total Assets	727		792
Liabilities:	'		'
Derivatives, net	48,854	[1]	63,893	[1]
Deferred compensation	2,591		2,364
Total liabilities	51,445		66,257
Recurring [Member] | Exchange Traded [Member]	'		'
Assets:	'		'
Available-for-sale securities	727		792
Recurring [Member] | Level 1 [Member]	'		'
Assets:	'		'
Total Assets	727		792
Liabilities:	'		'
Derivatives, net	-495	[1]	-735	[1]
Deferred compensation	0		0
Total liabilities	-495		-735
Recurring [Member] | Level 1 [Member] | Exchange Traded [Member]	'		'
Assets:	'		'
Available-for-sale securities	727		792
Recurring [Member] | Level 2 [Member]	'		'
Assets:	'		'
Total Assets	0		0
Liabilities:	'		'
Derivatives, net	0	[1]	0	[1]
Deferred compensation	2,591		2,364
Total liabilities	2,591		2,364
Recurring [Member] | Level 2 [Member] | Exchange Traded [Member]	'		'
Assets:	'		'
Available-for-sale securities	0		0
Recurring [Member] | Level 3 [Member]	'		'
Assets:	'		'
Total Assets	0		0
Liabilities:	'		'
Derivatives, net	49,349	[1]	64,628	[1]
Deferred compensation	0		0
Total liabilities	49,349		64,628
Recurring [Member] | Level 3 [Member] | Exchange Traded [Member]	'		'
Assets:	'		'
Available-for-sale securities	0		0
MGE [Member]	'		'
Liabilities:	'		'
Derivative asset, collateral offset	300		200
MGE [Member] | Recurring [Member]	'		'
Assets:	'		'
Total Assets	268		431
Liabilities:	'		'
Derivatives, net	48,854	[1]	63,893	[1]
Deferred compensation	2,591		2,364
Total liabilities	51,445		66,257
MGE [Member] | Recurring [Member] | Exchange Traded [Member]	'		'
Assets:	'		'
Available-for-sale securities	268		431
MGE [Member] | Recurring [Member] | Level 1 [Member]	'		'
Assets:	'		'
Total Assets	268		431
Liabilities:	'		'
Derivatives, net	-495	[1]	-735	[1]
Deferred compensation	0		0
Total liabilities	-495		-735
MGE [Member] | Recurring [Member] | Level 1 [Member] | Exchange Traded [Member]	'		'
Assets:	'		'
Available-for-sale securities	268		431
MGE [Member] | Recurring [Member] | Level 2 [Member]	'		'
Assets:	'		'
Total Assets	0		0
Liabilities:	'		'
Derivatives, net	0	[1]	0	[1]
Deferred compensation	2,591		2,364
Total liabilities	2,591		2,364
MGE [Member] | Recurring [Member] | Level 2 [Member] | Exchange Traded [Member]	'		'
Assets:	'		'
Available-for-sale securities	0		0
MGE [Member] | Recurring [Member] | Level 3 [Member]	'		'
Assets:	'		'
Total Assets	0		0
Liabilities:	'		'
Derivatives, net	49,349	[1]	64,628	[1]
Deferred compensation	0		0
Total liabilities	49,349		64,628
MGE [Member] | Recurring [Member] | Level 3 [Member] | Exchange Traded [Member]	'		'
Assets:	'		'
Available-for-sale securities	$0		$0
[1]	These amounts are shown gross and exclude $0.3 million and $0.2 million of collateral that was posted against derivative positions with counterparties as of June 30, 2014 and December 31, 2013, respectively.

Fair_Value_of_Financial_Instru4

Fair Value of Financial Instruments (Details-3)	6 Months Ended
	Jun. 30, 2014
Fair Value Inputs Assets Quantitative Information [Line Items]	'
Basis adjustment - on peak	96.90%
Basis adjustment - off peak	94.20%
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 [Abstract]	'
Internal generation	50.00%
Purchased power	50.00%
Maximum [Member]	'
Counterparty fuel mix [Abstract]	'
Internal generation	70.00%
Purchased power	30.00%

Fair_Value_of_Financial_Instru5

Fair Value of Financial Instruments (Details-4) (USD $)	3 Months Ended				6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'		'		'		'
Beginning balance,	($58,797)		($69,598)		($64,628)		($72,346)
Realized and unrealized gains (losses):	'		'		'		'
Included in regulatory liabilities (assets)	9,448		2,743		15,279		5,490
Included in other comprehensive income	0		0		0		0
Included in earnings	651		-44		7,218		-1,351
Included in current assets	-185		-123		-185		-123
Purchases	6,828		6,162		13,634		11,724
Sales	0		0		-60		-2
Issuances	0		0		0		0
Settlements	-7,294		-5,996		-20,607		-10,248
Transfers in and/or out of level 3	0		0		0		0
Ending balance,	-49,349		-66,856		-49,349		-66,856
Total gains (losses) included in earnings attributed to the change in unrealized gains (losses) related to assets and liabilities	0	[1]	0	[1]	0	[1]	0	[1]
Purchased Power Expense [Member]	'		'		'		'
Realized and unrealized gains (losses):	'		'		'		'
Included in earnings	$651	[1]	($44)	[1]	$7,218	[1]	($1,351)	[1]
[1]	MGE's exchange-traded derivative contracts, over-the-counter party transactions, ten-year purchased power agreement, and FTRs are subject to regulatory deferral. These derivatives are therefore marked to fair value and are offset with a corresponding regulatory asset or liability.

Segment_Information_Details

Segment Information (Details) (USD $)	3 Months Ended				6 Months Ended				12 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013		Dec. 31, 2013
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	$128,765		$128,288		$339,010		$295,525		'
Depreciation and amortization	-10,069		-9,530		-19,815		-19,154		'
Other operating expenses	-94,255		-94,261		-250,783		-214,246		'
Operating Income	24,441		24,497		68,412		62,125		'
Other income (deductions), net	3,548		2,711		8,100		6,020		'
Interest (expense) income, net	-4,868		-4,657		-9,409		-9,332		'
Income before income taxes	23,121		22,551		67,103		58,813		'
Income tax (provision) benefit	-9,034		-8,660		-25,299		-22,338		'
Net Income (Loss)	14,087		13,891		41,804		36,475		'
Segment Reporting Assets And Capital Expenditures [Abstract]	'		'		'		'		'
Assets	1,596,963		'		1,596,963		'		1,579,060
Capital expenditures	'		'		42,272		63,137		119,047
Electric [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	96,697		96,846		195,549		190,340		'
Gas [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	31,218		30,042		141,931		102,509		'
Non Regulated Energy [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	850		1,400		1,530		2,676		'
Transmission Investment [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	0		0		0		0		'
All Others [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	0		0		0		0		'
Operating Segments [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	128,765		128,288		339,010		295,525		'
Operating Segments [Member] | Electric [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	96,824		96,975		195,794		190,578		'
Depreciation and amortization	-6,641		-6,314		-12,978		-12,714		'
Other operating expenses	-76,812		-78,051		-154,713		-152,976		'
Operating Income	13,371		12,610		28,103		24,888		'
Other income (deductions), net	1,036		485		2,863		1,060		'
Interest (expense) income, net	-2,534		-2,315		-4,739		-4,719		'
Income before income taxes	11,873		10,780		26,227		21,229		'
Income tax (provision) benefit	-4,491		-3,694		-8,844		-7,127		'
Net Income (Loss)	7,382		7,086		17,383		14,102		'
Segment Reporting Assets And Capital Expenditures [Abstract]	'		'		'		'		'
Assets	915,507		'		915,507		'		899,257
Capital expenditures	'		'		34,133		'		100,146
Operating Segments [Member] | Gas [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	33,110		32,858		147,447		110,201		'
Depreciation and amortization	-1,562		-1,435		-3,125		-2,860		'
Other operating expenses	-29,865		-29,572		-122,708		-90,009		'
Operating Income	1,683		1,851		21,614		17,332		'
Other income (deductions), net	-17		-185		-52		-23		'
Interest (expense) income, net	-817		-759		-1,621		-1,437		'
Income before income taxes	849		907		19,941		15,872		'
Income tax (provision) benefit	-364		-606		-8,029		-6,595		'
Net Income (Loss)	485		301		11,912		9,277		'
Segment Reporting Assets And Capital Expenditures [Abstract]	'		'		'		'		'
Assets	247,229		'		247,229		'		265,694
Capital expenditures	'		'		7,289		'		15,554
Operating Segments [Member] | Non Regulated Energy [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	11,523		12,091		22,873		23,940		'
Depreciation and amortization	-1,855		-1,781		-3,689		-3,580		'
Other operating expenses	-30		-26		-70		-63		'
Operating Income	9,638		10,284		19,114		20,297		'
Other income (deductions), net	0		0		0		0		'
Interest (expense) income, net	-1,559		-1,605		-3,131		-3,218		'
Income before income taxes	8,079		8,679		15,983		17,079		'
Income tax (provision) benefit	-3,242		-3,483		-6,414		-6,740		'
Net Income (Loss)	4,837		5,196		9,569		10,339		'
Segment Reporting Assets And Capital Expenditures [Abstract]	'		'		'		'		'
Assets	286,855		'		286,855		'		288,116
Capital expenditures	'		'		850		'		3,347
Operating Segments [Member] | Transmission Investment [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	0		0		0		0		'
Depreciation and amortization	0		0		0		0		'
Other operating expenses	0		0		0		0		'
Operating Income	0		0		0		0		'
Other income (deductions), net	2,402		2,309		4,883		4,705		'
Interest (expense) income, net	0		0		0		0		'
Income before income taxes	2,402		2,309		4,883		4,705		'
Income tax (provision) benefit	-963		-927		-1,961		-1,898		'
Net Income (Loss)	1,439		1,382		2,922		2,807		'
Segment Reporting Assets And Capital Expenditures [Abstract]	'		'		'		'		'
Assets	66,617		'		66,617		'		64,504
Capital expenditures	'		'		0		'		0
Operating Segments [Member] | All Others [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	0		0		0		0		'
Depreciation and amortization	-11		0		-23		0		'
Other operating expenses	-240		-248		-396		-392		'
Operating Income	-251		-248		-419		-392		'
Other income (deductions), net	127		102		406		278		'
Interest (expense) income, net	42		22		82		42		'
Income before income taxes	-82		-124		69		-72		'
Income tax (provision) benefit	26		50		-51		22		'
Net Income (Loss)	-56		-74		18		-50		'
Segment Reporting Assets And Capital Expenditures [Abstract]	'		'		'		'		'
Assets	438,134		'		438,134		'		431,436
Capital expenditures	'		'		0		'		0
Operating Segments [Member] | Assets Not Allocated [Member]	'		'		'		'		'
Segment Reporting Assets And Capital Expenditures [Abstract]	'		'		'		'		'
Assets	31,187		'		31,187		'		19,853
Capital expenditures	'		'		0		'		0
Consolidation Elimination Entries [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	-12,692		-13,636		-27,104		-29,194		'
Depreciation and amortization	0		0		0		0		'
Other operating expenses	12,692		13,636		27,104		29,194		'
Operating Income	0		0		0		0		'
Other income (deductions), net	0		0		0		0		'
Interest (expense) income, net	0		0		0		0		'
Income before income taxes	0		0		0		0		'
Income tax (provision) benefit	0		0		0		0		'
Net Income (Loss)	0		0		0		0		'
Segment Reporting Assets And Capital Expenditures [Abstract]	'		'		'		'		'
Assets	-388,566		'		-388,566		'		-389,800
Capital expenditures	'		'		0		'		0
Consolidation Elimination Entries [Member] | Electric [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	127		129		245		238		'
Consolidation Elimination Entries [Member] | Gas [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	1,892		2,816		5,516		7,692		'
Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	10,673		10,691		21,343		21,264		'
Consolidation Elimination Entries [Member] | Transmission Investment [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	0		0		0		0		'
Consolidation Elimination Entries [Member] | All Others [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	0		0		0		0		'
MGE [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	128,775		128,288		339,031		295,525		'
Depreciation and amortization	-10,058		-9,530		-19,792		-19,154		'
Other operating expenses	-101,943	[1]	-101,582	[1]	-273,250	[1]	-234,292	[1]	'
Operating Income	16,774	[1]	17,176	[1]	45,989	[1]	42,079	[1]	'
Other income (deductions), net	2,279	[1]	1,468	[1]	5,288	[1]	3,820	[1]	'
Interest (expense) income, net	-4,910		-4,679		-9,491		-9,374		'
Income tax (provision) benefit	-7,918		-7,569		-22,842		-20,439		'
Net Income Including Noncontrolling Interest	14,143		13,965		41,786		36,525		'
Less Net Income Attributable to Noncontrolling Interest, net of tax	-6,621		-6,860		-13,131		-13,686		'
Net Income (Loss)	7,522		7,105		28,655		22,839		'
Segment Reporting Assets And Capital Expenditures [Abstract]	'		'		'		'		'
Assets	1,540,589		'		1,540,589		'		1,530,643
Capital expenditures	'		'		42,272		63,137		119,047
MGE [Member] | Electric [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	96,702		96,846		195,560		190,340		'
MGE [Member] | Gas [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	31,223		30,042		141,941		102,509		'
MGE [Member] | Non Regulated Energy [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	850		1,400		1,530		2,676		'
MGE [Member] | Transmission Investment [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	0		0		0		0		'
MGE [Member] | Operating Segments [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	128,775		128,288		339,031		295,525		'
MGE [Member] | Operating Segments [Member] | Electric [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	96,824		96,975		195,794		190,578		'
Depreciation and amortization	-6,641		-6,314		-12,978		-12,714		'
Other operating expenses	-81,165	[1]	-81,579	[1]	-163,211	[1]	-160,085	[1]	'
Operating Income	9,018	[1]	9,082	[1]	19,605	[1]	17,779	[1]	'
Other income (deductions), net	898	[1]	319	[1]	2,517	[1]	1,042	[1]	'
Interest (expense) income, net	-2,534		-2,315		-4,739		-4,719		'
Net Income Including Noncontrolling Interest	7,382		7,086		17,383		14,102		'
Less Net Income Attributable to Noncontrolling Interest, net of tax	0		0		0		0		'
Net Income (Loss)	7,382		7,086		17,383		14,102		'
Segment Reporting Assets And Capital Expenditures [Abstract]	'		'		'		'		'
Assets	915,507		'		915,507		'		899,257
Capital expenditures	'		'		34,133		'		100,146
MGE [Member] | Operating Segments [Member] | Gas [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	33,110		32,858		147,447		110,201		'
Depreciation and amortization	-1,562		-1,435		-3,125		-2,860		'
Other operating expenses	-30,188	[1]	-30,130	[1]	-130,638	[1]	-96,598	[1]	'
Operating Income	1,360	[1]	1,293	[1]	13,684	[1]	10,743	[1]	'
Other income (deductions), net	-58	[1]	-233	[1]	-151	[1]	-29	[1]	'
Interest (expense) income, net	-817		-759		-1,621		-1,437		'
Net Income Including Noncontrolling Interest	485		301		11,912		9,277		'
Less Net Income Attributable to Noncontrolling Interest, net of tax	0		0		0		0		'
Net Income (Loss)	485		301		11,912		9,277		'
Segment Reporting Assets And Capital Expenditures [Abstract]	'		'		'		'		'
Assets	247,229		'		247,229		'		265,694
Capital expenditures	'		'		7,289		'		15,554
MGE [Member] | Operating Segments [Member] | Non Regulated Energy [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	11,523		12,091		22,873		23,940		'
Depreciation and amortization	-1,855		-1,781		-3,689		-3,580		'
Other operating expenses	-3,272	[1]	-3,509	[1]	-6,484	[1]	-6,803	[1]	'
Operating Income	6,396	[1]	6,801	[1]	12,700	[1]	13,557	[1]	'
Other income (deductions), net	0	[1]	0	[1]	0	[1]	0	[1]	'
Interest (expense) income, net	-1,559		-1,605		-3,131		-3,218		'
Net Income Including Noncontrolling Interest	4,837		5,196		9,569		10,339		'
Less Net Income Attributable to Noncontrolling Interest, net of tax	0		0		0		0		'
Net Income (Loss)	4,837		5,196		9,569		10,339		'
Segment Reporting Assets And Capital Expenditures [Abstract]	'		'		'		'		'
Assets	286,805		'		286,805		'		288,066
Capital expenditures	'		'		850		'		3,347
MGE [Member] | Operating Segments [Member] | Transmission Investment [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	0		0		0		0		'
Depreciation and amortization	0		0		0		0		'
Other operating expenses	0	[1]	0	[1]	0	[1]	0	[1]	'
Operating Income	0	[1]	0	[1]	0	[1]	0	[1]	'
Other income (deductions), net	1,439	[1]	1,382	[1]	2,922	[1]	2,807	[1]	'
Interest (expense) income, net	0		0		0		0		'
Net Income Including Noncontrolling Interest	1,439		1,382		2,922		2,807		'
Less Net Income Attributable to Noncontrolling Interest, net of tax	0		0		0		0		'
Net Income (Loss)	1,439		1,382		2,922		2,807		'
Segment Reporting Assets And Capital Expenditures [Abstract]	'		'		'		'		'
Assets	66,617		'		66,617		'		64,504
Capital expenditures	'		'		0		'		0
MGE [Member] | Operating Segments [Member] | Assets Not Allocated [Member]	'		'		'		'		'
Segment Reporting Assets And Capital Expenditures [Abstract]	'		'		'		'		'
Assets	31,187		'		31,187		'		19,853
Capital expenditures	'		'		0		'		0
MGE [Member] | Consolidation Elimination Entries [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	-12,682		-13,636		-27,083		-29,194		'
Depreciation and amortization	0		0		0		0		'
Other operating expenses	12,682	[1]	13,636	[1]	27,083	[1]	29,194	[1]	'
Operating Income	0	[1]	0	[1]	0	[1]	0	[1]	'
Other income (deductions), net	0	[1]	0	[1]	0	[1]	0	[1]	'
Interest (expense) income, net	0		0		0		0		'
Net Income Including Noncontrolling Interest	0		0		0		0		'
Less Net Income Attributable to Noncontrolling Interest, net of tax	-6,621		-6,860		-13,131		-13,686		'
Net Income (Loss)	-6,621		-6,860		-13,131		-13,686		'
Segment Reporting Assets And Capital Expenditures [Abstract]	'		'		'		'		'
Assets	-6,756		'		-6,756		'		-6,731
Capital expenditures	'		'		0		'		0
MGE [Member] | Consolidation Elimination Entries [Member] | Electric [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	122		129		234		238		'
MGE [Member] | Consolidation Elimination Entries [Member] | Gas [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	1,887		2,816		5,506		7,692		'
MGE [Member] | Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	10,673		10,691		21,343		21,264		'
MGE [Member] | Consolidation Elimination Entries [Member] | Transmission Investment [Member]	'		'		'		'		'
Segment Reporting Information [Line Items]	'		'		'		'		'
Operating revenues	$0		$0		$0		$0		'
[1]	*Amounts are shown net of the related tax expense, consistent with the presentation on the consolidated MGE Income Statement.