Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2024

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,
	2024		2023
	(in thousands)
Electric Plant	$	6,034,159	$	5,462,229
Natural Gas Plant	1,615,228		1,506,943
Plant acquisition adjustment(1)	686,328		686,328
Common and Other Plant	277,623		267,132
Construction work in process	164,767		377,241
Total property, plant and equipment	8,778,105		8,299,873
Less accumulated depreciation	(2,019,142)		(1,930,688)
Less accumulated amortization	(360,688)		(329,384)
Net property, plant and equipment	$	6,398,275	$	6,039,801

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, 2024
Ownership percentages	23.4		%	8.7		%	10.0		%	30.0		%
Plant in service	$	157,572		$	65,426		$	52,430		$	330,888
Accumulated depreciation	49,573			39,025			39,887			137,153
December 31, 2023
Ownership percentages	23.4		%	8.7		%	10.0		%	30.0		%
Plant in service	$	156,696		$	64,132		$	52,630		$	323,793
Accumulated depreciation	44,525			37,178			39,393			127,381