Customer Financing (Allowance For Losses On Financing Receivables) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance - January 1	$ (16)	$ (21)	$ (49)
Write-offs	6	5	28
Ending balance - December 31	(10)	(16)	(21)
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Collectively evaluated for impairment	$ (10)	$ (16)	$ (21)