Registration of securities issued in business combination transactions

STOCK-BASED COMPENSATION PLAN (Details 2)

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STOCK-BASED COMPENSATION PLAN (Details 2) (USD $)
In Millions, except Share data, unless otherwise specified
 9 Months Ended 12 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Nonvested shares
          
Weighted Average Grant-Date Fair Value          
Total unrecognized compensation cost related to nonvested share-based compensation arrangements granted under the Stock Incentive Plan $ 21   $ 16    
Weighted-average period over which cost is expected to be recognized 1 year 2 months 12 days   10 months 24 days    
Value of share awards vested $ 21 $ 23 $ 23 $ 18 $ 12
Equity Awards
          
Nonvested shares          
Nonvested at the beginning of the period (in shares) 2,287,000 3,126,000 3,126,000    
Granted (in shares) 934,000   675,000    
Vested (in shares) (1,395,000)   (1,500,000)    
Forfeited (in shares) (27,000)   (14,000)    
Nonvested at the end of the period (in shares) 1,799,000   2,287,000    
Weighted Average Grant-Date Fair Value          
Nonvested at the beginning of the period (in dollars per share) $ 9.92 $ 6.95 $ 6.95    
Granted (in dollars per share) $ 13.41   $ 17.55    
Vested (in dollars per share) $ 7.07   $ 7.20    
Forfeited (in dollars per share) $ 15.26   $ 4.98    
Nonvested at the end of the period (in dollars per share) $ 13.86   $ 9.92    
Liability Awards
          
Nonvested shares          
Nonvested at the beginning of the period (in shares) 1,100,000 1,642,000 1,642,000    
Granted (in shares) 383,000   311,000    
Vested (in shares) (760,000)   (729,000)    
Forfeited (in shares) (63,000)   (124,000)    
Nonvested at the end of the period (in shares) 660,000   1,100,000    
Weighted Average Grant-Date Fair Value          
Nonvested at the beginning of the period (in dollars per share) $ 9.42 $ 6.05 $ 6.05    
Granted (in dollars per share) $ 13.41   $ 17.59    
Vested (in dollars per share) $ 6.53   $ 5.55    
Forfeited (in dollars per share) $ 15.32   $ 7.99    
Nonvested at the end of the period (in dollars per share) $ 14.51   $ 9.42    
Restricted stock units
          
Nonvested shares          
Vested (in shares) (72,161)   (115,045)    
Weighted Average Grant-Date Fair Value          
The number of restricted stock units vested at the balance sheet date (in shares) 516,338   444,177    
Vested restricted stock units reflected (in shares)     176,327