Long-term Financing and Sales of Receivables (Credit Quality Of Customer Financing Receivables And Allowance For Credit Losses) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Total Long-term Receivable	$ 63	$ 60
Current Billed Due		1
Past Due Under 90 Days		1
Past Due Over 90 Days	2	1
Municipal leases secured tax exempt
Debt Instrument [Line Items]
Total Long-term Receivable	20	35
Current Billed Due		0
Past Due Under 90 Days		0
Past Due Over 90 Days	0	0
Commercial loans and leases secured
Debt Instrument [Line Items]
Total Long-term Receivable	43	25
Current Billed Due		1
Past Due Under 90 Days		1
Past Due Over 90 Days	$ 2	$ 1