Customer Financing (Credit Risk Profile By Internally Assigned Ratings) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total carrying value of financing receivables	$ 2,597	$ 2,851
A Credit Rating [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total carrying value of financing receivables	34
BBB Credit Rating [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total carrying value of financing receivables	1,239	1,316
BB Credit Rating [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total carrying value of financing receivables	61	67
B Credit Rating [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total carrying value of financing receivables	58	103
CCC Credit Rating [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total carrying value of financing receivables	523	512
D Credit Rating [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total carrying value of financing receivables	587	653
Other Credit Rating [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total carrying value of financing receivables	$ 95	$ 200