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, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash paid for or (received from):
Interest expense	[1]	$ 82	$ 123	$ 134
Interest and dividend income		(3)	(2)	(1)
Income taxes, net of refunds		25	$ 52	$ 109
Interest Rate Swap Contracts [Member]
Cash paid for or (received from):
Amount received from termination of derivative		$ 12

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