Quarterly report pursuant to Section 13 or 15(d)

Supplemental Balance Sheet Information (Accounts Receivable) (Details)

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Supplemental Balance Sheet Information (Accounts Receivable) (Details) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2012
Dec. 31, 2011
Supplemental Balance Sheet Information [Abstract]    
Accounts receivable $ 963 $ 921
Allowance for doubtful accounts (1) (2)
Total accounts receivable, net $ 962 $ 919 [1]
[1] Amounts as of December 31, 2011 were derived from the December 31, 2011 audited financial statements.