Customer Financing (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Customer Financing [Line Items]
Financing Receivable, Individually Evaluated for Impairment	$ 57	$ 55
Impaired Financing Receivable, Recorded Investment	$ 46	$ 44
B Credit Rating [Member]
Customer Financing [Line Items]
Percentage of Credit Default Rates Applied to Customers	17.60%
BB Credit Rating [Member]
Customer Financing [Line Items]
Percentage of Credit Default Rates Applied to Customers	8.50%
BBB Credit Rating [Member]
Customer Financing [Line Items]
Percentage of Credit Default Rates Applied to Customers	1.10%