v2.4.0.6
Share Based Compensation (Details) (USD $)
In Millions, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2011
Y
Dec. 31, 2010
Y
Dec. 31, 2009
Y
Share-Based Compensation      
Aggregate tax benefit (reversal) related to share-based compensation     $ 6
Restricted Stock Units, Unrecognized Compensation Cost      
Period of recognition of total unrecognized compensation related to non-vested stock options, low end of range (in years) 2    
Fair Value Assumptions      
Expected option term (in years) 5.39 5.43 5.14
Expected dividend yield (as a percent) 1.29% 1.36% 1.47%
Expected volatility (as a percent) 45.45% 44.34% 43.35%
Risk-free interest rate (as a percent) 2.48% 2.56% 2.31%
Options      
Outstanding at beginning of period (in shares) 5,242,831    
Granted (in shares) 1,016,025    
Exercised (in shares) (682,560)    
Forfeited or expired (in shares) (161,649)    
Outstanding at end of period (in shares) 5,414,647 5,242,831  
Exercisable at end of period (in shares) 3,699,962    
Weighted-Average Exercise Price      
Outstanding balance at beginning of period (in dollars per share) $ 57.34    
Granted (in dollars per share) $ 71.2    
Exercised (in dollars per share) $ 33.76    
Forfeited or expired (in dollars per share) $ 72.82    
Outstanding balance at end of period (in dollars per share) $ 62.45 $ 57.34  
Exercisable balance at end of period (in dollars per share) $ 60.91    
Weighted-Average Remaining Contractual Term      
Outstanding at end of period (in years) 5.85    
Exercisable at end of period (in years) 4.56    
Aggregate Intrinsic Value      
Outstanding at end of period (in dollars) 30    
Exercisable at end of period (in dollars) 29    
Weighted-average grant date fair value (in dollars per share) $ 27.99 $ 23.70 $ 18.68
Total intrinsic value of options exercised (in dollars) 24 4 2
Stock option awards
     
Share-Based Compensation      
Share-based compensation expense 24 22 16
Restricted Stock Units, Unrecognized Compensation Cost      
Total unrecognized compensation related to non-vested awards (in dollars) 25    
Period of recognition of total unrecognized compensation related to non-vested stock options (in years) 2    
Restricted stock units
     
Share-Based Compensation      
Share-based compensation expense 25 38 1
Restricted Stock Units, Unrecognized Compensation Cost      
Total unrecognized compensation related to non-vested awards (in dollars) 43    
Period of recognition of total unrecognized compensation related to non-vested stock options, low end of range (in years) 2    
Restricted Stock Units      
Restricted stock units outstanding at beginning of period (in shares) 1,134,753    
Granted (in shares) 454,523    
Vested/issued (in shares) (214,006)    
Forfeited/cancelled (in shares) (189,415)    
Restricted stock units outstanding at end of period (in shares) 1,185,855 1,134,753  
Weighted-Average Grant-Date Fair Value      
Restricted stock units outstanding at beginning of period (in dollars per share) $ 67.15    
Granted (in dollars per share) $ 70.36 $ 58.67 $ 50.63
Vested/issued (in dollars per share) $ 93.42    
Forfeited/cancelled (in dollars per share) $ 79.82    
Restricted stock units outstanding at end of period (in dollars per share) $ 61.62 $ 67.15  
Restricted Stock Units, Additional Activity Information      
Unvested corresponding dividends accrued (in shares) 17,491    
Common shares issued, net of common shares withheld to cover taxes 214,006    
Common shares issued, net of common shares withheld to cover taxes, weighted-average fair value (in dollars per share) $ 70.12    
Payment/issuance deferred during period, vested restricted stock units and earned dividends (in shares) 851    
Deferred common share units including common shares representing accrued corresponding dividends, as of period end 27,790    
Shares cancelled related to performance-based restricted stock unit awards (in shares) 187,323    
Total fair value of restricted stock units vested (in dollars) $ 19    
2009 Equity Incentive Plan and Equity Incentive Plan | Stock option awards
     
Share-Based Compensation      
Expiration period of award (in years) P10Y    
Vesting period (in years) 3 years    
2009 Equity Incentive Plan and Equity Incentive Plan | Performance-based restricted stock units
     
Share-Based Compensation      
Vesting period (in years) 3 years    
Performance period (in years) 3 years    
2009 Equity Incentive Plan and Equity Incentive Plan | Performance-based restricted stock units | Maximum
     
Share-Based Compensation      
Percentage of award vested if performance target is achieved 200.00%    
2009 Equity Incentive Plan and Equity Incentive Plan | Performance-based restricted stock units | Minimum
     
Share-Based Compensation      
Percentage of award vested if performance target is achieved 50.00%    
2009 Equity Incentive Plan and Equity Incentive Plan | Time-vested restricted stock units
     
Share-Based Compensation      
Minimum vesting period (in years) P3Y    
Maximum vesting period (in years) P5Y    
Percentage of units vested 100%    
2009 EIP
     
Common Shares Reserved for Share-Based Awards      
Common shares reserved for grant of stock options, stock awards and other awards 10,000,000    
Common shares available for future grants 7,210,309    
2007 Directors' Plan
     
Common Shares Reserved for Share-Based Awards      
Common shares reserved for grant of stock options, stock awards and other awards 600,000    
Common shares available for future grants 412,184    
2007 Directors' Plan | Stock option awards
     
Share-Based Compensation      
Expiration period of award (in years) P10Y