Revenue from Contracts with Customers

6 Months Ended

Jun. 30, 2021

Revenue from Contract with Customer [Abstract]

Revenue from Contract with Customer [Text Block]

Revenue from Contracts with Customers

Nature of Goods and Services

We provide retail electric and natural gas services to three primary customer classes. Our residential customers 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 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 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 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 20-30 days after the billing date.

Disaggregation of Revenue

The following tables disaggregate our revenue by major source and customer class (in millions):

	Three Months Ended
	June 30, 2021						June 30, 2020
	Electric		Natural Gas		Total		Electric		Natural Gas		Total
Montana	$	69.9	$	25.5	$	95.4	$	70.6	$	17.5	$	88.1
South Dakota	14.4		6.4		20.8		14.6		4.7		19.3
Nebraska	—		3.9		3.9		—		3.5		3.5
Residential	84.3		35.8		120.1		85.2		25.7		110.9
Montana	84.6		13.0		97.6		77.4		8.2		85.6
South Dakota	24.1		4.3		28.4		23.2		2.9		26.1
Nebraska	—		1.8		1.8		—		1.5		1.5
Commercial	108.7		19.1		127.8		100.6		12.6		113.2
Industrial	9.2		0.2		9.4		9.2		0.1		9.3
Lighting, Governmental, Irrigation, and Interdepartmental	9.1		0.4		9.5		9.2		0.3		9.5
Total Customer Revenues	211.3		55.5		266.8		204.2		38.7		242.9
Other Tariff and Contract Based Revenues	25.4		9.1		34.5		14.3		8.6		22.9
Total Revenue from Contracts with Customers	236.7		64.6		301.3		218.5		47.3		265.8
Regulatory amortization and other	4.7		(7.8)		(3.1)		(0.6)		4.1		3.5
Total Revenues	$	241.4	$	56.8	$	298.2	$	217.9	$	51.4	$	269.3

	Six Months Ended
	June 30, 2021						June 30, 2020
	Electric		Natural Gas		Total		Electric		Natural Gas		Total
Montana	$	165.9	$	72.5	$	238.4	$	159.2	$	55.8	$	215.0
South Dakota	32.2		16.5		48.7		33.5		15.0		48.5
Nebraska	—		12.1		12.1		—		11.2		11.2
Residential	198.1		101.1		299.2		192.7		82.0		274.7
Montana	171.4		36.8		208.2		163.4		27.4		190.8
South Dakota	48.2		10.8		59.0		49.7		10.2		59.9
Nebraska	—		6.2		6.2		—		5.5		5.5
Commercial	219.6		53.8		273.4		213.1		43.1		256.2
Industrial	18.9		0.7		19.6		18.0		0.4		18.4
Lighting, Governmental, Irrigation, and Interdepartmental	13.7		0.9		14.6		14.5		0.6		15.1
Total Customer Revenues	450.3		156.5		606.8		438.3		126.1		564.4
Other Tariff and Contract Based Revenues	42.3		18.8		61.1		29.2		18.3		47.5
Total Revenue from Contracts with Customers	492.6		175.3		667.9		467.5		144.4		611.9
Regulatory amortization and other	18.9		12.2		31.1		(5.0)		(2.3)		(7.3)
Total Revenues	$	511.5	$	187.5	$	699.0	$	462.5	$	142.1	$	604.6