Segment Information (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2022		Jun. 30, 2021		Jun. 30, 2022		Jun. 30, 2021
Segment Reporting Information [Line Items]
Net income	$ 118		$ 112		$ 245		$ 241
Natural gas	167		80		601		284
Other	11		9		21		18
Regulated and Unregulated Operating Revenue	1,502		1,315		3,200		2,667
Affiliate Revenue	133		131		262		246
Total revenues
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue	1,503	[1],[2]	1,316	[1],[2]	3,201	[3],[4]	2,669	[3],[4]
Intersegment Eliminations
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue	(1)		(1)		(1)		(2)
Regulated Electric
Segment Reporting Information [Line Items]
Net income	113		112		211		219
Revenues Including Intersegment Revenues	1,324		1,227		2,578		2,366
Regulated Electric | Total revenues
Segment Reporting Information [Line Items]
Regulated Operating Revenue, Electric	1,324	[1]	1,226	[1]	2,578	[3]	2,365	[3]
Regulated Electric | Intersegment Eliminations
Segment Reporting Information [Line Items]
Regulated Operating Revenue, Electric	0		1		0		1
Regulated Natural Gas
Segment Reporting Information [Line Items]
Net income	4		(1)		33		19
Revenues Including Intersegment Revenues	168		80		602		285
Regulated Natural Gas | Total revenues
Segment Reporting Information [Line Items]
Natural gas	167	[2]	80	[2]	601	[4]	284	[4]
Regulated Natural Gas | Intersegment Eliminations
Segment Reporting Information [Line Items]
Natural gas	1		0		1		1
All Other
Segment Reporting Information [Line Items]
Net income	1		1		1		3
All Other | Total revenues
Segment Reporting Information [Line Items]
Other	$ 11		$ 9		$ 21		$ 18

[1] Operating revenues include $133 million and $131 million of affiliate electric revenue for the three months ended June 30, 2022 and 2021.

[2] Operating revenues include an immaterial amount of affiliate gas revenue for the three months ended June 30, 2022 and 2021.

[3] Operating revenues include $262 million and $246 million of affiliate electric revenue for the six months ended June 30, 2022 and 2021.

[4] Operating revenues include an immaterial amount of affiliate gas revenue for the six months ended June 30, 2022 and 2021.