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]
Unregulated Operating Revenue		$ 1	$ 1	$ 0
Regulated and Unregulated Operating Revenue		1,201	1,105	974
Depreciation and amortization		158	147	156
Interest charges and financing costs		42	40	38
Total income tax expense (benefit)		35	30	(7)
Net income		125	108	107
Electric, affiliates		202	189	168
Natural gas		198	182	119
Regulated Electric
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues		1,002	922	856
Depreciation and amortization		131	120	108
Interest charges and financing costs		38	36	34
Total income tax expense (benefit)		29	27	12
Net income		105	98	98
Regulated Natural Gas
Segment Reporting Information [Line Items]
Revenues Including Intersegment Revenues		198	183	119
Depreciation and amortization		27	27	48
Interest charges and financing costs		4	4	4
Total income tax expense (benefit)		6	2	(20)
Net income		17	7	7
All Other
Segment Reporting Information [Line Items]
Total income tax expense (benefit)		0	1	1
Net income		3	3	2
Total revenues
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue	[1]	1,201	1,106	975
Total revenues | Regulated Electric
Segment Reporting Information [Line Items]
Operating revenue, Regulated Electric	[1]	1,002	922	855
Total revenues | Regulated Natural Gas
Segment Reporting Information [Line Items]
Natural gas		198	182	119
Total revenues | All Other
Segment Reporting Information [Line Items]
Unregulated Operating Revenue		1	1	0
Intersegment Eliminations
Segment Reporting Information [Line Items]
Regulated and Unregulated Operating Revenue		0	(1)	(1)
Intersegment Eliminations | Regulated Electric
Segment Reporting Information [Line Items]
Operating revenue, Regulated Electric		0	0	1
Intersegment Eliminations | Regulated Natural Gas
Segment Reporting Information [Line Items]
Natural gas		$ 0	$ 1	$ 0

[1] Operating revenues include $202 million, $189 million and $168 million of affiliate electric revenue for the years ended Dec. 31, 2022, 2021 and 2020, respectively. See Note 12 for further information.