|
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 |