Revenue from Contracts with Customers

6 Months Ended

Jun. 30, 2020

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 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 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, 2020						June 30, 2019
	Electric		Natural Gas		Total		Electric		Natural Gas		Total
Montana	$	70.6	$	17.5	$	88.1	$	62.9	$	18.8	$	81.7
South Dakota	14.6		4.7		19.3		13.4		5.6		19.0
Nebraska	—		3.5		3.5		—		4.2		4.2
Residential	85.2		25.7		110.9		76.3		28.6		104.9
Montana	77.4		8.2		85.6		82.9		9.5		92.4
South Dakota	23.2		2.9		26.1		21.7		3.6		25.3
Nebraska	—		1.5		1.5		—		2.1		2.1
Commercial	100.6		12.6		113.2		104.6		15.2		119.8
Industrial	9.2		0.1		9.3		10.2		0.1		10.3
Lighting, Governmental, Irrigation, and Interdepartmental	9.2		0.3		9.5		7.8		0.2		8.0
Total Customer Revenues	204.2		38.7		242.9		198.9		44.1		243.0
Other Tariff and Contract Based Revenues	14.3		8.6		22.9		15.0		8.7		23.7
Total Revenue from Contracts with Customers	218.5		47.3		265.8		213.9		52.8		266.7
Regulatory amortization	(0.6)		4.1		3.5		5.8		(1.7)		4.1
Total Revenues	$	217.9	$	51.4	$	269.3	$	219.7	$	51.1	$	270.8

	Six Months Ended
	June 30, 2020						June 30, 2019
	Electric		Natural Gas		Total		Electric		Natural Gas		Total
Montana	$	159.2	$	55.8	$	215.0	$	157.0	$	64.4	$	221.4
South Dakota	33.5		15.0		48.5		31.4		18.7		50.1
Nebraska	—		11.2		11.2		—		13.8		13.8
Residential	192.7		82.0		274.7		188.4		96.9		285.3
Montana	163.4		27.4		190.8		169.6		32.5		202.1
South Dakota	49.7		10.2		59.9		44.9		12.8		57.7
Nebraska	—		5.5		5.5		—		7.4		7.4
Commercial	213.1		43.1		256.2		214.5		52.7		267.2
Industrial	18.0		0.4		18.4		21.8		0.6		22.4
Lighting, Governmental, Irrigation, and Interdepartmental	14.5		0.6		15.1		12.9		0.7		13.6
Total Customer Revenues	438.3		126.1		564.4		437.6		150.9		588.5
Other Tariff and Contract Based Revenues	29.2		18.3		47.5		31.2		18.9		50.1
Total Revenue from Contracts with Customers	467.5		144.4		611.9		468.8		169.8		638.6
Regulatory amortization	(5.0)		(2.3)		(7.3)		23.9		(7.6)		16.3
Total Revenues	$	462.5	$	142.1	$	604.6	$	492.7	$	162.2	$	654.9