Customer Financing (Financing Receivable Credit Quality Indicators) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 2,563	$ 2,851
A Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	34
BBB Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	1,221	1,316
BB Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	62	67
B Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	54	103
CCC Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	534	512
D Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	556	653
Other Credit Rating [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivables	$ 102	$ 200