The minimum common equity ratio required to avoid dividend payment restirctions to the parent company.

No definition available.

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Namespace Prefix:	mgee_
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Aggregate dividends paid during the period for each share of common stock outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

+ Details

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Balance Type:	na
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- Definition

Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The distributions of earnings to an entity that is affiliated with the reporting entity by means of direct or indirect ownership.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585

+ Details

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Balance Type:	credit
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=mgee_MgeMember
Namespace Prefix:
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- Details

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Common Equity (Details)	3 Months Ended								12 Months Ended
Common Equity (Details)	Dec. 31, 2019 $ / shares	Sep. 30, 2019 $ / shares	Jun. 30, 2019 $ / shares	Mar. 31, 2019 $ / shares	Dec. 31, 2018 $ / shares	Sep. 30, 2018 $ / shares	Jun. 30, 2018 $ / shares	Mar. 31, 2018 $ / shares	Dec. 31, 2019 USD ($) $ / shares	Dec. 31, 2018 USD ($) $ / shares	Dec. 31, 2017 USD ($) $ / shares
Class of Stock [Line Items]
Common stock dividends declared									$ 47,842,000	$ 45,762,000	$ 43,682,000
Common stock dividends declared (in dollars per share) \| $ / shares	$ 0.353	$ 0.353	$ 0.338	$ 0.338	$ 0.338	$ 0.338	$ 0.323	$ 0.323	$ 1.38	$ 1.32	$ 1.26
MGE [Member]
Class of Stock [Line Items]
Cash dividends paid to parent by MGE									$ 0	$ 0	$ 45,000,000
MGE [Member] \| Minimum [Member]
Class of Stock [Line Items]
Dividend restrictions, common equity ratio									0.55