Registration of securities issued in business combination transactions

Accounts Receivable (Activity in the Allowance for Doubtful Accounts) (Details)

v2.4.0.8
Accounts Receivable (Activity in the Allowance for Doubtful Accounts) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Allowance for Doubtful Accounts Receivable [Roll Forward]      
Balance beginning of year $ 74 $ 79 $ 66
Additions charged to expense 81 75 68
Deductions write-offs (72) (80) (55)
Balance end of year $ 83 $ 74 $ 79