Fair Value of Financial Assets and Liabilities - Impact of Derivative Activities on Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments designated as fair value hedges	$ 0	$ 0	$ 0	$ 0
Financial Impact of Qualifying Fair Value Hedges on Earnings [Abstract]
Derivative instruments designated as fair value hedges	0	0	0	0
Other Derivative Instruments | Natural Gas Commodity
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax (gains) losses reclassified into income during the period from regulatory assets and (liabilities)	0	0	(1)	(1)
Other Derivative Instruments | Electric Commodity Contract
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax fair value gains (losses) recognized during the period in regulatory (assets) and liabilities	$ 1	$ 3	$ 1	$ 3