Customer Financing (Financing Receivable Credit Quality Indicators) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Carrying value of financing receivables	$ 2,006	$ 1,905
B B B Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Carrying value of financing receivables	990	$ 1,055
B B Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Carrying value of financing receivables	555
B Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Carrying value of financing receivables	272	$ 633
C C C Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Carrying value of financing receivables	100	131
Other Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Carrying value of financing receivables	$ 89	$ 86