Customer Financing (Financing Receivable Credit Quality Indicators) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	$ 1,876	$ 1,905
BBB Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Percentage Of Credit Default Rates Applied To Customers	2.00%
Total financing receivables	$ 973	$ 1,055
BB Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Percentage Of Credit Default Rates Applied To Customers	10.00%
Total financing receivables	$ 536
B Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Percentage Of Credit Default Rates Applied To Customers	16.00%
Total financing receivables	$ 258	$ 633
CCC Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	23	131
Other Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Total financing receivables	$ 86	$ 86