Supplemental Cash Flow Information (Schedule Of Supplemental Information Relating To The Unaudited Condensed Consolidated Statements Of Cash Flows) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash paid for or (received from):
Interest expense	[1]	$ 81	$ 82	$ 122
Interest and dividend income		(1)	(3)	(2)
Income taxes, net of refunds		$ 4	$ 25	$ 52

[1] For the year ended December 31, 2019, excludes $12 million received in connection with our terminated interest rate swap.