Revenue from Contracts with Customers Disaggegation of Revenue

12 Months Ended

Dec. 31, 2022

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, 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 Customer Revenues	974.8		360.6		1,335.4
Other Tariff and Contract Based Revenues	85.7		38.3		124.0
Total Revenue from Contracts with Customers	1,060.5		398.9		1,459.4
Regulatory amortization	46.1		(27.7)		18.4
Total Revenues	$	1,106.6	$	371.2	$	1,477.8

December 31, 2021	Electric		Natural Gas		Total
Montana	334.6		126.0		460.6
South Dakota	65.4		26.6		92.0
Nebraska	—		21.0		21.0
Residential	400.0		173.6		573.6
Montana	356.7		64.7		421.4
South Dakota	102.5		19.1		121.6
Nebraska	—		11.4		11.4
Commercial	459.2		95.2		554.4
Industrial	37.9		1.1		39.0
Lighting, Governmental, Irrigation, and Interdepartmental	32.1		1.4		33.5
Total Customer Revenues	929.2		271.3		1,200.5
Other Tariff and Contract Based Revenues	89.5		36.8		126.3
Total Revenue from Contracts with Customers	1,018.7		308.1		1,326.8
Regulatory amortization	33.5		12.0		45.5
Total Revenues	$	1,052.2	$	320.1	$	1,372.3

December 31, 2020	Electric		Natural Gas		Total
Montana	320.8		103.5		424.3
South Dakota	66.6		21.5		88.1
Nebraska	—		16.9		16.9
Residential	387.4		141.9		529.3
Montana	338.3		51.3		389.6
South Dakota	101.1		14.3		115.4
Nebraska	—		8.1		8.1
Commercial	439.4		73.7		513.1
Industrial	36.8		0.9		37.7
Lighting, Governmental, Irrigation, and Interdepartmental	31.8		0.9		32.7
Total Customer Revenues	895.4		217.4		1,112.8
Other Tariff and Contract Based Revenues	58.5		35.5		94.0
Total Revenue from Contracts with Customers	953.9		252.9		1,206.8
Regulatory amortization	(13.1)		5.0		(8.1)
Total Revenues	$	940.8	$	257.9	$	1,198.7