Valuation And Qualifying Accounts And Reserves (Schedule Of Valuation And Qualifying Accounts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Balance at Beginning of Year	$ 110	$ 84	$ 73
Additions	47	26	44
Deductions	(66)	(19)	(26)
Other	$ 9	19	(7)
Balance at End of Year		$ 110	$ 84