Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2022

Property, Plant and Equipment [Abstract]

Major classifications of property, plant and equipment

The following table presents the major classifications of our property, plant and equipment (in thousands):

	December 31,
	2022		2021(1)
	(in thousands)
Electric Plant	$	5,205,788	$	4,848,349
Natural Gas Plant	1,371,045		1,252,229
Plant acquisition adjustment(2)	686,328		686,328
Common and Other Plant	268,970		235,746
Construction work in process	311,652		294,617
Total property, plant and equipment	7,843,783		7,317,269
Less accumulated depreciation	(1,880,265)		(1,787,550)
Less accumulated amortization	(306,038)		(282,487)
Net property, plant and equipment	$	5,657,480	$	5,247,232

Schedule of jointly owned utility plants

Information relating to our ownership interest in these facilities is as follows (in thousands):

	Big Stone (SD)			Neal #4 (IA)			Coyote (ND)			Colstrip Unit 4 (MT)
December 31, 2022
Ownership percentages	23.4		%	8.7		%	10.0		%	30.0		%
Plant in service	$	155,567		$	63,032		$	51,796		$	326,584
Accumulated depreciation	42,884			35,847			38,955			121,830
December 31, 2021
Ownership percentages	23.4		%	8.7		%	10.0		%	30.0		%
Plant in service	$	154,375		$	62,865		$	51,652		$	324,433
Accumulated depreciation	42,102			34,629			38,453			113,805