Supplementary Financial Statement Information (Schedule Of Interest Income And Interest Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure Text Block Supplement [Abstract]
Interest expense	$ 734	$ 758	$ 695
Interest income	198	186	175
Capitalized interest costs	$ 30	$ 25	$ 28