Retirement Plans (Projected Benefit Obligation, Fair Values Of Plan Assets And Amounts Recognized In The Balance Sheet) (Details) - USD ($) $ in Millions	4 Months Ended	8 Months Ended	12 Months Ended
	Apr. 30, 2021	Dec. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Amounts recognized in the consolidated balance sheet
Pension and other postretirement benefits - current			$ (38)	$ (39)
Pension and other postretirement benefits - noncurrent			(697)	(1,044)
Pension [Member]
Change in projected benefit obligation (PBO)
PBO at beginning of the period			2,510	3,477
Service cost	$ 32	$ 53	51	69
Interest cost	31	69	129	106
Actuarial gain	(328)	(30)	(44)	(867)
Benefits paid			(204)	(75)
Settlements			0	(200)
PBO at end of the period		3,477	2,442	2,510	$ 3,477
Change in plan assets
Fair value of plan assets at beginning of the period			2,033	2,655
Actual return on plan assets			305	(523)
Employer contribution			134	176	42
Settlements				(200)
Benefits paid			(204)	(75)
Fair value of plan assets at end of the period		2,655	2,268	2,033	2,655
Funded status			(174)	(477)
Amounts recognized in the consolidated balance sheet
Pension and other postretirement benefits - noncurrent			(174)	(477)
OPEB [Member]
Change in projected benefit obligation (PBO)
PBO at beginning of the period			606	897
Service cost	7	11	8	13
Interest cost	9	18	31	31
Plan amendments			(45)	(41)
Plan participants' contributions			11	10
Actuarial gain	$ (99)	(37)	3	(248)
Benefits paid			(53)	(56)
PBO at end of the period		897	561	606	897
Change in plan assets
Fair value of plan assets at beginning of the period
Plan participants' contributions			11	10
Employer contribution			42	46
Benefits paid			(53)	(56)
Fair value of plan assets at end of the period
Funded status			(561)	(606)
Amounts recognized in the consolidated balance sheet
Pension and other postretirement benefits - current			(38)	(39)
Pension and other postretirement benefits - noncurrent			(523)	(567)
Accumulated other comprehensive gain		$ (75)	$ (125)	$ (102)	$ (75)