MGE Energy Inc Comprehensive Income (Details) (MGE Energy [Member], USD $) In Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
MGE Energy [Member]
Other Comprehensive Income [Line Items]
Net Income	$ 12,723	$ 11,552	$ 30,506	$ 25,812
Unrealized gain (loss) on available-for-sale securities, net of tax	9	(88)	81	(80)
Reclassification of realized gain on available-for-sale securities, net of tax	(15)	0	(15)	0
Total comprehensive income	12,717	11,464	30,572	25,732
Other Comprehensive Income Taxes
Unrealized gain (loss) on available-for-sale securities, taxes	6	(59)	54	(54)
Reclassification of realized gain on available-for-sale securities, taxes	$ (10)	$ 0	$ (10)	$ 0

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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+ Details

- Definition

This element represents Other Comprehensive Income or Loss, Net of Tax, for the period. Includes deferred gains or losses on qualifying hedges, unrealized holding gains or losses on available-for-sale securities, minimum pension liability, and cumulative translation adjustment. While for technical reasons this element has no balance attribute, the default assumption is a credit balance consistent with its label.

+ References

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+ Details

- Definition

Reclassification adjustment for unrealized gains or losses realized upon the sale of securities, after tax.

+ References

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+ Details

- Definition

Tax effect on the reclassification adjustment for gains or losses realized upon the sale of securities during the period.

+ References+ Details

- Definition

Appreciation or loss in value (before reclassification adjustment) of the total of unsold securities during the period being reported on, net of tax. Reclassification adjustments include: (1) the unrealized holding gain (loss), net of tax, at the date of the transfer for a debt security from the held-to-maturity category transferred into the available-for-sale category. Also includes the unrealized gain (loss) at the date of transfer for a debt security from the available-for-sale category transferred into the held-to-maturity category; (2) the unrealized gains (losses) realized upon the sale of securities, after tax; and (3) the unrealized gains (losses) realized upon the write-down of securities, after tax.

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+ Details

- Definition

Tax effect on gross appreciation or the gross loss in value of the total of unsold securities during the period being reported on.

+ References+ Details