Revenue from Contracts with Customers

3 Months Ended

Mar. 31, 2019

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 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 by major source and customer class (in millions):

	Three Months Ended
	March 31, 2019							March 31, 2018
	Electric		Natural Gas			Total		Electric			Natural Gas			Total
Montana	$	94.1	$	45.6		$	139.7	$	87.2		$	40.9		$	128.1
South Dakota	18.0		13.1			31.1		18.7			11.4			30.1
Nebraska	—		9.6			9.6		—			11.4			11.4
Residential	112.1		68.3			180.4		105.9			63.7			169.6
Montana	86.7		23.0			109.7		83.6			20.6			104.2
South Dakota	23.2		9.2			32.4		24.0			7.9			31.9
Nebraska	—		5.3			5.3		—			6.1			6.1
Commercial	109.9		37.5			147.4		107.6			34.6			142.2
Industrial	11.6		0.5			12.1		10.8			0.5			11.3
Lighting, Governmental, Irrigation, and Interdepartmental	5.1		0.5			5.6		5.0			0.5			5.5
Total Customer Revenues	238.7		106.8			345.5		229.3			99.3			328.6
Other Tariff and Contract Based Revenues	16.2		10.2			26.4		17.8			10.3			28.1
Total Revenue from Contracts with Customers	254.9		117.0			371.9		247.1			109.6			356.7
Regulatory amortization	18.1		(5.8		)	12.3		(8.8		)	(6.4		)	(15.2		)
Total Revenues	$	273.0	$	111.2		$	384.2	$	238.3		$	103.2		$	341.5