Rate Matters	12 Months Ended
Dec. 31, 2011
Rate Matters Disclosure [Abstract]
Rate Matters	17. Rate Matters - MGE Energy and MGE. a. Rate Proceedings. On December 15, 2011, under a limited reopener of MGE's last rate order, the PSCW authorized MGE to increase 2012 rates for retail electric customers by 4.3% or $15.7 million and to increase gas rates by 0.3% or $0.6 million. The change in retail electric rates was driven by MGE's electric fuel and purchased power costs, increased transmission costs, an update to the Elm Road Units' costs, and an increase for energy efficiency programs. The PSCW also approved deferral of CSAPR costs. On January 12, 2011, the PSCW authorized MGE to increase 2011 rates for retail electric customers by 2.3% or $8.0 million and to increase gas rates by 1.0% or $1.9 million. The increase in retail electric rates is driven by costs for MGE's share of the Elm Road Units. Pursuant to the provisions of this rate order, the fuel rules bandwidth effective January 1, 2011, will be plus or minus 2%. Authorized return on common stock equity was set at 10.3% based on a 58.1% utility common equity. On December 22, 2009, the PSCW authorized MGE to increase 2010 rates for retail electric customers by 3.3% or $11.9 million, while gas rates decreased 0.74% or $1.5 million. The increase in retail electric rates was driven by costs for MGE's share of the Elm Road Units and transmission reliability enhancements. Pursuant to the provisions of this rate order, the fuel rules bandwidth effective January 1, 2010, was plus or minus 2%. Authorized return on common stock equity was set at 10.4% based on a 55.3% utility common equity. On December 18, 2008, under a limited reopener, the PSCW authorized MGE to decrease 2009 rates for retail electric customers by 0.74% or $2.7 million, while gas rates remained unchanged from 2008. The decrease in retail electric rates was driven by a decrease in fuel and purchased power costs, decrease in costs associated with the Elm Road Units and a decrease in ATC transmission costs. The PSCW also approved deferred accounting for incremental pension and other postretirement benefit costs above the levels included in rates. b. Fuel Rules. The PSCW approved new fuel rules that became effective January 1, 2011. The new rules require the PSCW and Wisconsin utilities to automatically defer electric fuel-related costs that fall outside a symmetrical cost tolerance band. Any over/under recovery of the deferred costs is determined on an annual basis and will be adjusted in future billings to electric retail customers. Under fuel rules, MGE would defer costs, less any excess revenues, if its actual electric fuel costs exceed 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 are less than 98% of the electric fuel costs allowed in that order. As of December 31, 2011, MGE did not defer any electric fuel-related costs. In 2010, a refund of $0.3 million of over collected 2009 fuel costs was refunded on customers' April 2010 bills. In May 2009, the PSCW authorized an interim fuel credit as a result of decreased actual electric fuel costs. The order was subject to refund with interest at 10.8%. The interim fuel credit resulted in $4.6 million reduction in customer revenues. In 2008, MGE recorded a $5.5 million fuel reduction to other electric revenues to account for a fuel refund. In March 2009, the PSCW completed their audit of the 2008 electric fuel costs and issued a final order, which applied this refund to customers' accounts in March 2009.

Rate Matters

12 Months Ended

Dec. 31, 2011

17. Rate Matters - MGE Energy and MGE.

a. Rate Proceedings.

On December 15, 2011, under a limited reopener of MGE's last rate order, the PSCW authorized MGE to increase 2012 rates for retail electric customers by 4.3% or $15.7 million and to increase gas rates by 0.3% or $0.6 million. The change in retail electric rates was driven by MGE's electric fuel and purchased power costs, increased transmission costs, an update to the Elm Road Units' costs, and an increase for energy efficiency programs. The PSCW also approved deferral of CSAPR costs.

On January 12, 2011, the PSCW authorized MGE to increase 2011 rates for retail electric customers by 2.3% or $8.0 million and to increase gas rates by 1.0% or $1.9 million. The increase in retail electric rates is driven by costs for MGE's share of the Elm Road Units. Pursuant to the provisions of this rate order, the fuel rules bandwidth effective January 1, 2011, will be plus or minus 2%. Authorized return on common stock equity was set at 10.3% based on a 58.1% utility common equity.

On December 22, 2009, the PSCW authorized MGE to increase 2010 rates for retail electric customers by 3.3% or $11.9 million, while gas rates decreased 0.74% or $1.5 million. The increase in retail electric rates was driven by costs for MGE's share of the Elm Road Units and transmission reliability enhancements. Pursuant to the provisions of this rate order, the fuel rules bandwidth effective January 1, 2010, was plus or minus 2%. Authorized return on common stock equity was set at 10.4% based on a 55.3% utility common equity.

On December 18, 2008, under a limited reopener, the PSCW authorized MGE to decrease 2009 rates for retail electric customers by 0.74% or $2.7 million, while gas rates remained unchanged from 2008. The decrease in retail electric rates was driven by a decrease in fuel and purchased power costs, decrease in costs associated with the Elm Road Units and a decrease in ATC transmission costs. The PSCW also approved deferred accounting for incremental pension and other postretirement benefit costs above the levels included in rates.

b. Fuel Rules.

The PSCW approved new fuel rules that became effective January 1, 2011. The new rules require the PSCW and Wisconsin utilities to automatically defer electric fuel-related costs that fall outside a symmetrical cost tolerance band. Any over/under recovery of the deferred costs is determined on an annual basis and will be adjusted in future billings to electric retail customers. Under fuel rules, MGE would defer costs, less any excess revenues, if its actual electric fuel costs exceed 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 are less than 98% of the electric fuel costs allowed in that order.

As of December 31, 2011, MGE did not defer any electric fuel-related costs. In 2010, a refund of $0.3 million of over collected 2009 fuel costs was refunded on customers' April 2010 bills. In May 2009, the PSCW authorized an interim fuel credit as a result of decreased actual electric fuel costs. The order was subject to refund with interest at 10.8%. The interim fuel credit resulted in $4.6 million reduction in customer revenues. In 2008, MGE recorded a $5.5 million fuel reduction to other electric revenues to account for a fuel refund. In March 2009, the PSCW completed their audit of the 2008 electric fuel costs and issued a final order, which applied this refund to customers' accounts in March 2009.