Property Plant and Equipment Property Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Public Utility Property, Plant, and Equipment

Major classes of property, plant and equipment

(Millions of Dollars)	Dec. 31, 2023		Dec. 31, 2022
Property, plant and equipment, net
Electric plant	$	16,698	$	15,771
Natural gas plant	6,321		5,949
Common and other property	1,472		1,415
Plant to be retired (a)	1,203		1,305
CWIP	1,310		877
Total property, plant and equipment	27,004		25,317
Less accumulated depreciation	(5,969)		(5,665)
Property, plant and equipment, net	$	21,035	$	19,652

Schedule of Jointly Owned Utility Plants

Joint Ownership of Generation, Transmission and Gas Facilities

Jointly owned assets as of Dec. 31, 2023:

(Millions of Dollars, Except Percent Owned)	Plant in Service		Accumulated Depreciation		Percent Owned
Electric generation:
Hayden Unit 1	$	157	$	108	76	%
Hayden Unit 2	151		87		37
Hayden common facilities	44		31		53
Craig Units 1 and 2	82		55		10
Craig common facilities	39		25		7
Comanche Unit 3	916		191		67
Comanche common facilities	29		4		77
Electric transmission:
Transmission and other facilities	189		75		Various
Gas transmission:
Rifle, CO to Avon, CO	28		9		60
Gas transmission compressor	8		2		50
Total (a)	$	1,643	$	587