v2.4.0.6
Valuation Accounts Valuation Accounts (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Allowance for doubtful accounts [Roll Forward]      
Balance at beginning of period $ 54 $ 42 $ 32
Additions charged to costs and expenses 7 17 10
Other additions 0 0 0
Deductions 0 5 0
Balance at end of period $ 61 $ 54 $ 42