Valuation And Qualifying Accounts And Reserves (Schedule Of Valuation And Qualifying Accounts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Balance at Beginning of Year	$ 73	$ 72	$ 70
Additions	44	3	16
Deductions	(26)	(6)	(16)
Other	(7)	4	2
Balance at End of Year		73	$ 72
Allowance for Doubtful Accounts Receivable	$ 84	$ 73