Segments and Related Information (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Operating revenue, Regulated Natural Gas		$ 1,860	$ 1,355	$ 1,024
Unregulated Operating Revenue		53	47	43
Regulated and Unregulated Operating Revenue		5,708	4,815	4,183
Depreciation and amortization		848	744	655
Interest charges and financing costs		260	234	224
Total income tax expense		37	33	45
Net income (loss)		727	660	588
Intercompany Revenue		5	5	5
Regulated Electric
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues		3,796	3,414	3,117
Depreciation and amortization		650	566	497
Interest charges and financing costs		200	179	173
Total income tax expense		(11)	(16)	13
Net income (loss)		550	495	460
Regulated Natural Gas
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues		1,860	1,355	1,024
Depreciation and amortization		190	171	152
Interest charges and financing costs		59	53	50
Total income tax expense		49	45	29
Net income (loss)		180	168	126
All Other
Segment Reporting Information [Line Items]
Depreciation and amortization		8	7	6
Interest charges and financing costs		1	2	1
Total income tax expense		(1)	4	3
Net income (loss)		(3)	(3)	2
Total revenues
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue	[1]	5,709	4,816	4,184
Total revenues | Regulated Electric
Segment Reporting Information [Line Items]
Electric		3,795	3,413	3,116
Total revenues | All Other
Segment Reporting Information [Line Items]
Unregulated Operating Revenue	[1]	53	47	43
Intersegment Eliminations
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue		(1)	(1)	(1)
Intersegment Eliminations | Regulated Electric
Segment Reporting Information [Line Items]
Electric		$ 1	$ 1	$ 1

[1] Operating revenues include $5 million of other affiliate revenue for the years ended Dec. 31, 2022, 2021 and 2020, respectively. See Note 13 for further information.