Customer Financing (Allowance For Losses On Financing Receivables) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance - January 1	$ (12)	$ (10)	$ (16)
Write-offs	3	(2)	6
Ending balance - December 31	(9)	(12)	(10)
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	$ (9)	$ (12)	$ (10)