Segments and Related Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024		Dec. 31, 2023		Dec. 31, 2022
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues	$ 1,131		$ 1,177		$ 1,200
Unregulated Operating Revenue	1		1		1
Regulated and Unregulated Operating Revenue	1,131		1,177		1,201
Depreciation and amortization	186		170		158
Interest charges and financing costs	61		50		42
Total income tax expense	40		40		35
Net income	134		136		125
Electric, affiliates	216		204		202
Natural gas	135		157		198
Cost of natural gas sold and transported	55		80		116
Operating and maintenance expenses	230		239		223
Other income (expense), net	3		2		(2)
Regulated Electric
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues	995		1,019
Regulated Natural Gas
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues	136		158
All Other
Segment Reporting Information [Line Items]
Net income	4		1		3
Total revenues
Segment Reporting Information [Line Items]
Depreciation and amortization	186		170		158
Interest charges and financing costs	61		50		42
Total income tax expense	39		40		35
Net income	130		135		122
Regulated Operating Revenue	1,130	[1]	1,176	[2]	1,200	[3]
Electric Fuel and Purchased Power	397		422		463
Cost of natural gas sold and transported	55		80		116
Operating and maintenance expenses	229		238		225
Other income (expense), net	34		42	[4]	39
Total revenues | Regulated Electric
Segment Reporting Information [Line Items]
Operating revenue, Regulated Electric	995	[1]	1,019	[2]	1,002	[3]
Depreciation and amortization	156		142		131
Interest charges and financing costs	54		45		38
Total income tax expense	37		38		29
Net income	121		126		105
Electric Fuel and Purchased Power	397		422		463
Cost of natural gas sold and transported	0		0		0
Operating and maintenance expenses	201		210		202
Other income (expense), net	29		36	[4]	34
Total revenues | Regulated Natural Gas
Segment Reporting Information [Line Items]
Depreciation and amortization	30		28		27
Interest charges and financing costs	7		5		4
Total income tax expense	2		2		6
Net income	9		9		17
Natural gas	135	[1]	157	[2]	198	[3]
Electric Fuel and Purchased Power	0		0		0
Cost of natural gas sold and transported	55		80		116
Operating and maintenance expenses	28		28		23
Other income (expense), net	5		6	[4]	5
Total revenues | All Other
Segment Reporting Information [Line Items]
Unregulated Operating Revenue	1		1		$ 1
Intersegment Eliminations
Segment Reporting Information [Line Items]
Regulated Operating Revenue	1		1
Intersegment Eliminations | Regulated Electric
Segment Reporting Information [Line Items]
Operating revenue, Regulated Electric	0		0
Intersegment Eliminations | Regulated Natural Gas
Segment Reporting Information [Line Items]
Natural gas	$ 1		$ 1

[1] Operating revenues include $216 million of affiliate electric revenue. See Note 12 for further information.

[2] Operating revenues include $204 million of affiliate electric revenue. See Note 12 for further information.

[3] Operating revenues include $202 million of affiliate electric revenue. See Note 12 for further information.

[4] Other segment expenses, net, for 2023 additionally includes workforce reduction expenses.