Rate Matters	3 Months Ended
Mar. 31, 2015
Regulated Operations [Abstract]
Rate Matters	Rate Matters - MGE Energy and MGE. a. Rate Proceedings. On December 23, 2014, the PSCW authorized MGE to increase 2015 rates for retail electric customers by 3.8% or $15.4 million and to decrease gas rates by 2.0% or $3.8 million. The increase in retail electric rates cover costs associated with the construction of emission-reduction equipment at Columbia, improvements and reliability of the state's electric transmission system, fuel and purchased power related to coal delivery costs, partially offset by lower cost as a result of market conditions for pension and post-retirement benefit costs. The authorized return on common stock equity is 10.2%. The PSCW approved changes to customer rates and rate design for gas service. Gas rate design consists of a fixed monthly customer charge and a variable charge tied to actual usage, in addition to the separate charge for natural gas commodity costs (PGA). The change shifted more of the rate recovery to the monthly charge, reflecting the related fixed costs of providing gas services, and reduced the variable usage-based charge. Thus, gas net income is expected to be more evenly distributed during the year and less sensitive to weather. A similar, but much smaller rate design shift was also approved for electric rates. On July 26, 2013, the PSCW authorized MGE to freeze electric and natural gas rates at 2013 levels for 2014. The order authorized 100% AFUDC on the Columbia scrubber construction project and deferral of increased costs related to ATC and MISO network upgrade fees. As part of the rate freeze plan authorized by the PSCW, effective January 1, 2014, approximately $6.3 million associated with a 2012 fuel rule surplus credit was required to be refunded to customers and was amortized in 2014. The fuel credit accrued interest at MGE's weighted cost of capital. The authorized return on equity remained 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 March 31, 2015, MGE has deferred $2.4 million (to be returned to customers in a future period) of 2015 electric fuel-related savings that are outside the range authorized by the PSCW. As part of the rate freeze plan authorized by the PSCW for 2014, $1.6 million of the approximately $6.3 million associated with the 2012 fuel rule credit was amortized against purchased power expense during the three months ended March 31, 2014. c. Purchased Gas Adjustment Clause. MGE's natural gas rates are subject to a fuel adjustment clause designed to recover or refund the difference between the actual cost of purchased gas and the amount included in rates. Differences between the amounts billed to customers and the actual costs recoverable are deferred and recovered or refunded in future periods by means of prospective monthly adjustments to rates. At March 31, 2015 and December 31, 2014, MGE had over collected $6.7 million and $1.2 million, respectively, which was recorded in other current liabilities on the consolidated balance sheets.

Rate Matters

3 Months Ended

Mar. 31, 2015

Rate Matters - MGE Energy and MGE.

a. Rate Proceedings.

On December 23, 2014, the PSCW authorized MGE to increase 2015 rates for retail electric customers by 3.8% or $15.4 million and to decrease gas rates by 2.0% or $3.8 million. The increase in retail electric rates cover costs associated with the construction of emission-reduction equipment at Columbia, improvements and reliability of the state's electric transmission system, fuel and purchased power related to coal delivery costs, partially offset by lower cost as a result of market conditions for pension and post-retirement benefit costs. The authorized return on common stock equity is 10.2%.

The PSCW approved changes to customer rates and rate design for gas service. Gas rate design consists of a fixed monthly customer charge and a variable charge tied to actual usage, in addition to the separate charge for natural gas commodity costs (PGA). The change shifted more of the rate recovery to the monthly charge, reflecting the related fixed costs of providing gas services, and reduced the variable usage-based charge. Thus, gas net income is expected to be more evenly distributed during the year and less sensitive to weather. A similar, but much smaller rate design shift was also approved for electric rates.

On July 26, 2013, the PSCW authorized MGE to freeze electric and natural gas rates at 2013 levels for 2014. The order authorized 100% AFUDC on the Columbia scrubber construction project and deferral of increased costs related to ATC and MISO network upgrade fees. As part of the rate freeze plan authorized by the PSCW, effective January 1, 2014, approximately $6.3 million associated with a 2012 fuel rule surplus credit was required to be refunded to customers and was amortized in 2014. The fuel credit accrued interest at MGE's weighted cost of capital. The authorized return on equity remained 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 March 31, 2015, MGE has deferred $2.4 million (to be returned to customers in a future period) of 2015 electric fuel-related savings that are outside the range authorized by the PSCW. As part of the rate freeze plan authorized by the PSCW for 2014, $1.6 million of the approximately $6.3 million associated with the 2012 fuel rule credit was amortized against purchased power expense during the three months ended March 31, 2014.

c. Purchased Gas Adjustment Clause.

MGE's natural gas rates are subject to a fuel adjustment clause designed to recover or refund the difference between the actual cost of purchased gas and the amount included in rates. Differences between the amounts billed to customers and the actual costs recoverable are deferred and recovered or refunded in future periods by means of prospective monthly adjustments to rates. At March 31, 2015 and December 31, 2014, MGE had over collected $6.7 million and $1.2 million, respectively, which was recorded in other current liabilities on the consolidated balance sheets.