Revenue

6 Months Ended

Jun. 30, 2018

Revenue from Contract with Customer [Abstract]

Revenue from Contract with Customer

Revenue - MGE Energy and MGE.

Revenues disaggregated by revenue source were as follows:

		Three Months Ended				Six Months Ended
(In thousands)		June 30,				June 30,
Electric revenues		2018		2017		2018		2017
Residential	$	32,217	$	31,634	$	65,476	$	64,987
Commercial(a)		50,174		54,721		97,626		104,885
Industrial		4,630		4,516		7,525		8,731
Other-retail/municipal		8,527		9,661		16,814		18,682
Total retail		95,548		100,532		187,441		197,285
Sales to the market		2,795		1,050		4,829		2,022
Other revenues		454		562		924		991
Adjustments to revenues		270		162		264		332
Total electric revenues		99,067		102,306		193,458		200,630
Gas revenues
Residential		15,620		15,140		52,171		49,043
Commercial/Industrial(a)		8,206		7,842		33,158		30,890
Total retail		23,826		22,982		85,329		79,933
Gas transportation		1,053		991		2,189		2,341
Other revenues		101		108		227		233
Total gas revenues		24,980		24,081		87,745		82,507
Non-regulated energy revenues		215		76		691		149
Total Operating Revenue(a)	$	124,262	$	126,463		281,894	$	283,286

(a)In 2017, MGE had less than $0.1 million of revenues related to CNG vehicle fuel servicing.No revenue was recognized for fuel servicing by MGE Energy in 2017.

Performance Obligations

A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account. A contract's transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. The majority of MGE Energy's and MGE's contracts have a single performance obligation.

Retail Revenue (Residential, Commercial, Industrial, and Other Retail/Municipal)

Retail revenue of electric and gas utility service represent MGE's core business activities. Tariffs are approved by the PSCW through a rate order and provide MGE's customers with the standard terms and conditions, including pricing terms. The performance obligation to deliver electricity or gas is satisfied over time as the customer simultaneously receives and consumes the commodities provided by MGE. MGE recognizes revenues as the commodity is delivered to customers. Meters are read on a systematic basis throughout the month based on established meter-reading schedules and the customer is subsequently billed for their services. At the end of the month, MGE accrues an estimate for the unbilled amount of commodities delivered to customers. The unbilled revenue estimate is based on daily system demand volumes, weather factors, estimated line losses, estimated customer usage by class, and applicable customer rates.

Utility Cost Recovery Mechanisms

MGE's tariff rates include a provision for fuel cost recovery. The PSCW allows Wisconsin utilities to defer electric fuel-related costs, less excess revenues, that fall outside a symmetrical cost tolerance band. Any over/under recovery of the actual costs in a given year is determined in the following year and is then reflected in future billings to electric retail customers. Over-collection of fuel-related costs that are outside the approved range will be recognized as a reduction of revenue. Prior to adoption of the new revenue recognition guidance, effective January 1, 2018, over-collected fuel-related costs were reflected in "Purchased power" expense. Under-collection of these costs will continue to be recognized in "Purchased power" expense in the consolidated statements of income of MGE Energy and MGE. The cumulative effects of these deferred amounts will be recorded in "Regulatory assets" or "Regulatory liabilities" on the consolidated balance sheets of MGE Energy and MGE until they are reflected in future billings to customers. See Footnote 10.b. for further information.

MGE received a PSCW order in January 2018 to defer the over-collection of income tax expense collected in customer rates as a result of the Tax Cuts and Jobs Act (the Tax Act) reduction in the income tax rate to 21 percent. See Footnote 5 for further information.

MGE has other cost recovery mechanisms, any over-collection of the difference between actual costs incurred and the amount of costs collected from customers is recorded as a reduction of revenue in the period incurred.

Sales to the Market

Sales to the market include energy charges, capacity or demand charges, and ancillary charges represented by wholesale sales of electricity made to third parties who are not ultimate users of the electricity. Most of these sales are spot market transactions on the markets operated by MISO. Each transaction is considered a performance obligation and revenue is recognized in the period in which energy charges, capacity or demand charges, and ancillary services are sold into MISO. MGE reports on a net basis, transactions on the MISO markets in which it buys and sells power within the same hour to meet electric energy delivery requirements.

Transportation of Gas

MGE has contracts under which MGE provides gas transportation services to customers whom have elected to purchase gas from a third party and have the gas delivered via pipelines within MGE's service territory. Revenue is recognized as service is rendered or gas is delivered to customers. Tariffs are approved by the PSCW through a rate order and provide gas transportation customers with the standard terms and conditions, including pricing terms.