Revenue Recognition (Summary Of Changes In Contract Liabilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Revenue Recognition [Abstract]
Contract current liabilities, Beginning balance	$ 28	$ 27
Contract current liabilities, Revenue recognized included in opening contract balance	(37)	(30)
Contract current liabilities, Credits granted, excluding amounts recognized as revenue	37	26
Contract current liabilities, Reclassified between current and concurrent	5	5
Contract current liabilities, Ending balance	33	28
Contract noncurrent liabilities, Beginning balance	17	11
Contract noncurrent liabilities, Revenue recognized included in opening contract balance	(14)	(11)
Contract noncurrent liabilities, Credits granted, excluding amounts recognized as revenue	18	22
Contract noncurrent liabilities, Reclassified between current and noncurrent	(5)	(5)
Contract noncurrent liabilities, Ending balance	$ 16	$ 17