Revenue Recognition (Summary Of Changes In Contract Liabilities) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Revenue Recognition [Abstract]
Contract current liabilities, Beginning balance	$ 34	$ 33
Contract current liabilities, Revenue recognized included in opening contract balance	(11)	(8)
Contract current liabilities, Credits granted, excluding amounts recognized as revenue	12	8
Contract current liabilities, Reclassified between current and noncurrent	(1)
Contract current liabilities, Ending balance	34	33
Contract noncurrent liabilities, Beginning balance	14	17
Contract noncurrent liabilities, Revenue recognized included in opening contract balance	(5)	(5)
Contract noncurrent liabilities, Credits granted, excluding amounts recognized as revenue	3	3
Contract noncurrent liabilities, Reclassified between current and noncurrent	1
Contract noncurrent liabilities, Ending balance	$ 13	$ 15