Employee Retirement Benefits - Unrecognized Amounts (Details) - Pension Benefits [Member] - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Components of AOCI:
Unrecognized prior service benefit	$ 2	$ 2
Unrecognized losses	41	(60)
Total	43	(58)
Tax effects on components of AOCI [Abstract]
Tax expense (benefit) related to unrecognized prior service benefit (cost)	1	1
Tax expense (benefit) related to unrecognized gain (loss)	7	(24)
Unrecognized amounts included in regulatory assets (liabilities) [Abstract]
Unrecognized prior service benefit	(1)	(1)
Unrecognized losses (gains)	(80)	163
Total	$ (81)	$ 162