Long-Term Customer Financing And Sales Of Receivables (Credit Quality Of Customer Financing Receivables And Allowance For Credit Losses) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Total Long-term Receivable	$ 132	$ 177
Current Billed Due	1	1
Past Due Under 90 Days	2	2
Past Due Over 90 Days	2	0
Municipal Leases Secured Tax Exempt [Member]
Debt Instrument [Line Items]
Total Long-term Receivable	9	14
Current Billed Due	0	0
Past Due Under 90 Days	0	0
Past Due Over 90 Days	0	0
Commercial Loans And Leases Secured [Member]
Debt Instrument [Line Items]
Total Long-term Receivable	82	61
Current Billed Due	1	1
Past Due Under 90 Days	2	2
Past Due Over 90 Days	2	0
Commercial Loans Unsecured [Member]
Debt Instrument [Line Items]
Total Long-term Receivable	41	102
Current Billed Due	0	0
Past Due Under 90 Days	0	0
Past Due Over 90 Days	$ 0	$ 0