Segments and Related Information (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Operating revenue, Regulated Natural Gas		$ 1,734	$ 1,860	$ 1,355
Unregulated Operating Revenue		54	53	47
Regulated and Unregulated Operating Revenue		5,519	5,708	4,815
Depreciation and amortization		924	848	744
Interest charges and financing costs		292	260	234
Total income tax expense		29	37	33
Net income (loss)		695	727	660
Intercompany Revenue		5	5	5
Regulated Electric
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues		3,732	3,796	3,414
Depreciation and amortization		692	650	566
Interest charges and financing costs		224	200	179
Total income tax expense		(2)	(11)	(16)
Net income (loss)		529	550	495
Regulated Natural Gas
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues		1,734	1,860	1,355
Depreciation and amortization		224	190	171
Interest charges and financing costs		67	59	53
Total income tax expense		37	49	45
Net income (loss)		149	180	168
All Other
Segment Reporting Information [Line Items]
Depreciation and amortization		8	8	7
Interest charges and financing costs		1	1	2
Total income tax expense		(6)	(1)	4
Net income (loss)		17	(3)	(3)
Total revenues
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue	[1]	5,520	5,709	4,816
Total revenues | Regulated Electric
Segment Reporting Information [Line Items]
Electric		3,731	3,795	3,413
Total revenues | All Other
Segment Reporting Information [Line Items]
Unregulated Operating Revenue	[1]	54	53	47
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, 2023, 2022 and 2021, respectively. See Note 13 for further information.