Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2019
(Provision) Benefit for Income Taxes	$ (12)	$ (32)
Loss Before Income Taxes	(465)	(210)
Goodwill, Impairment Loss	229	0	$ 0
Asset Write-Downs and Other	49	18
Restructuring and Transformation Charges	$ 20	$ 25
Forecast
Uncertain tax positions, estimated for next twelve months				$ 16

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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