Customer Financing (Financing Receivable Credit Quality Indicators) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	$ 1,855	$ 2,386
BBB Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	883	1,170
BB Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	430	627
B Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	135	177
CCC Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	$ 407	$ 412