Fair Value of Financial Instruments Financial Assets and Liabilities Recognized at Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Assets:
Cash equivalents	$ 0	$ 0
Debt securities:
Domestic government	19	18
Corporate credit	7	7
Money market funds measured at NAV (2)	7	6
Non-qualified benefit plan trust: (2)
Money market funds	1	2
Debt securities—domestic government	3	3
Assets from price risk management activities: (1) (3)
Electricity	32	22
Natural gas	15	11
Total	10	9
Assets, Fair Value Disclosure	87	72
Liabilities from price risk management activities: (1) (3)
Electricity	68	73
Natural gas	132	166
Total	200	239
Fair Value, Inputs, Level 1 [Member]
Assets:
Cash equivalents	0	0
Debt securities:
Domestic government	10	9
Corporate credit	0	0
Non-qualified benefit plan trust: (2)
Money market funds	1	2
Debt securities—domestic government	3	3
Assets from price risk management activities: (1) (3)
Electricity	0	0
Natural gas	0	0
Total	14	14
Liabilities from price risk management activities: (1) (3)
Electricity	0	0
Natural gas	0	0
Total	0	0
Fair Value, Inputs, Level 2 [Member]
Assets:
Cash equivalents	0	0
Debt securities:
Domestic government	9	9
Corporate credit	7	7
Non-qualified benefit plan trust: (2)
Money market funds	0	0
Debt securities—domestic government	0	0
Assets from price risk management activities: (1) (3)
Electricity	22	8
Natural gas	15	11
Total	53	35
Liabilities from price risk management activities: (1) (3)
Electricity	36	30
Natural gas	109	150
Total	145	180
Fair Value, Inputs, Level 3 [Member]
Assets:
Cash equivalents	0	0
Debt securities:
Domestic government	0	0
Corporate credit	0	0
Non-qualified benefit plan trust: (2)
Money market funds	0	0
Debt securities—domestic government	0	0
Assets from price risk management activities: (1) (3)
Electricity	10	14
Natural gas	0	0
Total	10	14
Liabilities from price risk management activities: (1) (3)
Electricity	32	43
Natural gas	23	16
Total	$ 55	$ 59