Customer Financing (Financing Receivable Credit Quality Indicators) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Carrying value of financing receivables	$ 2,162	$ 2,289
BBB Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Carrying value of financing receivables	1,200	1,324
BB Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Carrying value of financing receivables	508	538
B Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Carrying value of financing receivables	405	383
CCC Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Carrying value of financing receivables	$ 49	$ 44