Segment Information (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2023		Sep. 30, 2022		Sep. 30, 2023		Sep. 30, 2022
Segment Reporting Information [Line Items]
Net income		$ 31		$ 40		$ 102		$ 102
Other		1		0		1		0
Regulated and Unregulated Operating Revenue		279	[1]	294	[1]	870		900
Affiliate Revenue		50		51
Natural gas		15		20		116		133
Total revenues
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue	[2]					871		900
Intersegment Eliminations
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue						(1)		0
Regulated Electric
Segment Reporting Information [Line Items]
Net income		32		42		95		89
Regulated Electric | Total revenues
Segment Reporting Information [Line Items]
Regulated Operating Revenue, Electric		263	[1]	274	[1]	753	[2]	767	[2]
Regulated Natural Gas
Segment Reporting Information [Line Items]
Net income		(3)		(3)		5		11
Revenues Including Intersegment Revenues		15		20		117		133
Regulated Natural Gas | Total revenues
Segment Reporting Information [Line Items]
Natural gas						116		133
Regulated Natural Gas | Intersegment Eliminations
Segment Reporting Information [Line Items]
Natural gas						1		0
All Other
Segment Reporting Information [Line Items]
Net income		2		1		2		2
All Other | Total revenues
Segment Reporting Information [Line Items]
Other		$ 1		$ 0		$ 1		$ 0

[1] Total revenues include $50 million and $51 million of affiliate electric revenue for the three months ended Sept. 30, 2023 and 2022, respectively.

[2] Total revenues include $151 million and $150 million of affiliate electric revenue for the nine months ended Sept. 30, 2023 and 2022, respectively.