Customer Financing (Financing Receivable Credit Quality Indicators) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Carrying value of financing receivables	$ 1,487	$ 1,855
BBB Credit Rating [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Carrying value of financing receivables	612	883
BB Credit Rating [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Carrying value of financing receivables	349	430
B Credit Rating [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Carrying value of financing receivables	128	135
CCC Credit Rating [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Carrying value of financing receivables	$ 398	$ 407