Revenue Recognition (Changes In Contract Assets And Contract Liabilities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Revenue Recognition [Abstract]
Contract current assets, Beginning balance	$ 44	$ 40
Contract current assets, Revenue recognized included in opening contract balance	(39)	(49)
Contract current assets, Credits granted, excluding amounts recognized as revenue	30	49
Contract current assets, Reclassified between Current and Noncurrent	5	4
Contract current assets, Reclassified to held for sale	(3)
Contract current assets, Ending balance	37	44
Contract noncurrent assets, Beginning balance	25	37
Contract noncurrent assets, Revenue recognized included in opening contract balance	(12)	(8)
Contract noncurrent assets, Credits granted, excluding amounts recognized as revenue	1
Contract noncurrent assets, Reclassified between Current and NonCurrent	(5)	(4)
Contract noncurrent assets, Reclassified to held for sale	(1)
Contract noncurrent assets, Ending balance	8	25
Contract current liabilities, Beginning balance	49	41
Contract current liabilities, Revenue recognized included in opening contract balance	(81)	(106)
Contract current liabilities, Cash received, excluding amounts recognized as revenue	78	129
Contract current liabilities, Reclassified to held for sale	(5)	(10)
Contract current liabilities, Other		(5)
Contract current liabilities, Ending balance	41	49
Contract noncurrent liabilities, Beginning balance	22	19
Contract noncurrent liabilities, Revenue recognized included in opening contract balance	(17)	(13)
Contract noncurrent liabilities, Cash received, excluding amounts recognized as revenue	16	6
Contract noncurrent liabilities, Reclassified between Current and NonCurrent		10
Contract noncurrent liabilities, Ending balance	$ 21	$ 22