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]
Unregulated Operating Revenue		$ 1	$ 1	$ 1
Regulated and Unregulated Operating Revenue		1,177	1,201	1,105
Depreciation and amortization		170	158	147
Interest charges and financing costs		50	42	40
Total income tax expense		40	35	30
Net income		136	125	108
Electric, affiliates		204	202	189
Natural gas		157	198	182
Regulated Electric
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues	[1]	1,019	1,002	922
Depreciation and amortization		142	131	120
Interest charges and financing costs		45	38	36
Total income tax expense		38	29	27
Net income		126	105	98
Regulated Natural Gas
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues		158	198	183
Depreciation and amortization		28	27	27
Interest charges and financing costs		5	4	4
Total income tax expense		2	6	2
Net income		9	17	7
All Other
Segment Reporting Information [Line Items]
Total income tax expense		0	0	1
Net income		1	3	3
Total revenues
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue	[1]	1,178	1,201	1,106
Total revenues | Regulated Natural Gas
Segment Reporting Information [Line Items]
Natural gas		157	198	182
Total revenues | All Other
Segment Reporting Information [Line Items]
Unregulated Operating Revenue		1	1	1
Intersegment Eliminations
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue		(1)	0	(1)
Intersegment Eliminations | Regulated Natural Gas
Segment Reporting Information [Line Items]
Natural gas		$ 1	$ 0	$ 1

[1] Operating revenues include $204 million, $202 million and $189 million of affiliate electric revenue for the years ended Dec. 31, 2023, 2022 and 2021, respectively. See Note 12 for further information.