Retirement Benefits Unamortized Prior Service Credit Rollforward (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Amortization of:
Prior service credit	$ 1	$ 1	$ 10
Tax expense (benefit) related to above items	0	0	(2)
Change in unamortized benefit plan costs	1	1	8
Pension Benefits
Amortization of:
Prior service credit	0	0	9
Tax expense (benefit) related to above items	0	0	(2)
Change in unamortized benefit plan costs	0	0	7
Medical and Life Benefits
Amortization of:
Prior service credit	1	1	1
Tax expense (benefit) related to above items	0	0	0
Change in unamortized benefit plan costs	$ 1	$ 1	$ 1