Other Postretirement Employee Benefit Plans (Funded Status Of The Domestic Plans) (Details) - Other postretirement benefits - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Change in benefit obligation:
Benefit obligation at beginning of year	$ (139)	$ (142)
Service cost	0	0	$ 1
Interest cost	(4)	(5)
Actuarial gain (loss)	(15)	(4)
Retiree contributions	(2)	(2)
Benefits paid	12	14
Benefit obligation at end of year	(148)	(139)	$ (142)
Change in plan assets:
Fair value of plan assets	0	0
Funded status	$ (148)	$ (139)