Investment And Other Income (Components Of Investment And Other Income) (Details) - USD ($) $ in Millions	3 Months Ended		4 Months Ended	5 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Apr. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Successor [Member]
Interest and dividend income	$ 1			$ 1
Pension and OPEB benefit (costs)	(36)			(40)
All other, net	(2)
Investment and other income (loss), net	$ (37)			$ (39)
Predecessor [Member]
Interest and dividend income					$ 4
Pension and OPEB benefit (costs)		$ (16)	$ 2		(35)
All other, net		2	(1)		2
Investment and other income (loss), net		$ (14)	$ 1		$ (29)