Revenue from Contracts with Customers Disaggegation of Revenue

12 Months Ended

Dec. 31, 2024

Revenue from Contract with Customer [Abstract]

Revenue from Contract with Customer [Text Block]

(19) Revenue from Contracts with Customers

    Accounting Policy

Our revenues are primarily from tariff based sales. We provide gas and/or electricity to customers under these tariffs without a defined contractual term (at-will). As the revenue from these arrangements is equivalent to the electricity or gas supplied and billed in that period (including estimated billings), there will not be a shift in the timing or pattern of revenue recognition for such sales. We have also completed the evaluation of our other revenue streams, including those tied to longer term contractual commitments. These revenue streams have performance obligations that are satisfied at a point in time, and do not have a shift in the timing or pattern of revenue recognition.

Customers are billed monthly on a cycle basis. To match revenues with associated expenses, we accrue unbilled revenues for electric and natural gas services delivered to customers, but not yet billed at month-end.

Nature of Goods and Services

We currently provide retail electric and natural gas services to three primary customer classes. Our largest customer class consists of residential customers, which include single private dwellings and individual apartments. Our commercial customers consist primarily of main street businesses, and our industrial customers consist primarily of manufacturing and processing businesses that turn raw materials into products.

Electric Segment - Our regulated electric utility business primarily provides generation, transmission, and distribution services to our customers in our Montana and South Dakota jurisdictions. We recognize revenue when electricity is delivered to the customer. Payments on our tariff based sales are generally due in 20-30 days after the billing date.

Natural Gas Segment - Our regulated natural gas utility business primarily provides production, storage, transmission, and distribution services to our customers in our Montana, South Dakota, and Nebraska jurisdictions. We recognize revenue when natural gas is delivered to the customer. Payments on our tariff based sales are generally due in 20-30 days after the billing date.

Disaggregation of Revenue

The following tables disaggregate our revenue for the twelve months ended by major source and customer class (in millions):

December 31, 2024	Electric		Natural Gas		Total
Montana	398.8		110.2		509.0
South Dakota	70.0		26.9		96.9
Nebraska	—		21.2		21.2
Residential	468.8		158.3		627.1
Montana	409.0		59.9		468.9
South Dakota	111.8		18.1		129.9
Nebraska	—		11.4		11.4
Commercial	520.8		89.4		610.2
Industrial	46.6		1.0		47.6
Lighting, governmental, irrigation, and interdepartmental	32.8		1.4		34.2
Total Retail Revenues	1,069.0		250.1		1,319.1
Regulatory Amortization	24.9		19.0		43.9
Transmission	97.1		—		97.1
Wholesale and other	9.7		44.1		53.8
Total Revenues	$	1,200.7	$	313.2	$	1,513.9

December 31, 2023	Electric		Natural Gas		Total
Montana	408.3		136.1		544.4
South Dakota	67.9		36.6		104.5
Nebraska	—		35.5		35.5
Residential	476.2		208.2		684.4
Montana	431.4		73.7		505.1
South Dakota	103.2		25.9		129.1
Nebraska	—		22.1		22.1
Commercial	534.6		121.7		656.3
Industrial	46.0		1.4		47.4
Lighting, governmental, irrigation, and interdepartmental	32.7		1.7		34.4
Total Retail Revenues	1,089.5		333.0		1,422.5
Regulatory Amortization	(105.6)		(25.0)		(130.6)
Transmission	78.4		—		78.4
Wholesale and other	6.5		45.3		51.8
Total Revenues(1)	$	1,068.8	$	353.3	$	1,422.1

December 31, 2022	Electric		Natural Gas		Total
Montana	357.4		152.3		509.7
South Dakota	69.8		39.2		109.0
Nebraska	—		35.8		35.8
Residential	427.2		227.3		654.5
Montana	368.6		79.3		447.9
South Dakota	108.2		28.5		136.7
Nebraska	—		22.1		22.1
Commercial	476.8		129.9		606.7
Industrial	39.8		1.5		41.3
Lighting, governmental, irrigation, and interdepartmental	31.0		1.9		32.9
Total Retail Revenues	974.8		360.6		1,335.4
Regulatory Amortization	46.4		(28.1)		18.3
Transmission	77.8		—		77.8
Wholesale and other	7.6		38.7		46.3
Total Revenues(1)	$	1,106.6	$	371.2	$	1,477.8