v2.4.0.6
Schedule of Valuation and Qualifying Accounts Disclosure (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Allowance for Doubtful Accounts [Member]
      
Movement in Valuation Allowances and Reserves [Roll Forward]      
Balance at Beginning of Year $ 2 $ 14 $ 42
Charged to Expense 7 (12) 2
Deductions 0 [1] 0 [1] (30) [1]
Charged to Other Accounts 4 0 0
Balance at End of Year 13 2 14
Deferred Tax Asset Valuation Allowance [Member]
      
Movement in Valuation Allowances and Reserves [Roll Forward]      
Balance at Beginning of Year 2,386 2,572 2,685
Charged to Expense (50) (186) (113)
Deductions 0 [1] 0 [1] 0 [1]
Charged to Other Accounts 0 0 0
Balance at End of Year $ 2,336 $ 2,386 $ 2,572
[1] Represents write-offs of accounts considered to be uncollectible and previously reserved.