Supplemental Cash Flow Information (Schedule Of Supplemental Information Relating To The Unaudited Condensed Consolidated Statements Of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Cash paid for or (received from):
Interest expense	$ 16	$ 19
Interest and dividend income	(1)	(1)
Income taxes, net of refunds	$ 2	1
Interest rate swap agreement termination fee		11
Interest rate swap contracts
Cash paid for or (received from):
Amount received from termination of derivative		$ 11	$ 12