v2.4.0.6
Stock Compensation Plans (Details 2) (USD $)
In Thousands, except Per Share data, unless otherwise specified
 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Employee Stock Option
      
Employee Stock Options and Stock Awards      
Continuous years of service before options begin to vest (in years) 2 years    
Minimum continuous years of service before options are completely vested (in years) P4Y    
Maximum contractual term (in years) P10Y    
Stock Options      
Outstanding at beginning of period (in shares) 13,919 15,937 19,666
Options issued in connection with the Hewitt acquisition (in shares)   4,545  
Granted (in shares) 80 143 1,551
Exercised (in shares) (4,546) (6,197) (4,475)
Forfeited and expired (in shares) (337) (509) (805)
Outstanding at end of period (in shares) 9,116 13,919 15,937
Exercisable at end of period (in shares) 7,833 11,293 9,884
Shares available for grant (in shares) 24,508 22,777 8,257
Weighted-Average Exercise Price      
Outstanding at beginning of period (in dollars per share) $ 32 $ 33 $ 31
Granted (in dollars per share) $ 53 $ 38 $ 38
Options issued in connection with the Hewitt acquisition (in dollars per share)   $ 22  
Exercised (in dollars per share) $ 32 $ 27 $ 27
Forfeited and expired (in dollars per share) $ 36 $ 35 $ 38
Outstanding at end of period (in dollars per share) $ 32 $ 32 $ 33
Exercisable at end of period (in dollars per share) $ 30 $ 30 $ 31
Leadership Performance Plan ("LPP") cycle
      
Weighted Average assumptions, weighted average expected life and estimated fair value of options      
Weighted average volatility (as a percent)     35.50%
Expected dividend yield (as a percent)     1.30%
Risk-free rate (as a percent)     1.50%
Weighted average expected life (in years)     4.40
Weighted average estimated fair value per share (in dollars per share)     $ 12.19
Stock Options      
Granted (in shares)     1,000
Weighted-Average Exercise Price      
Granted (in dollars per share)     $ 39
Leadership Performance Plan ("LPP") cycle | Employee Stock Option
      
Employee Stock Options and Stock Awards      
Vesting period (in years) 3 years    
Maximum contractual term (in years) P6Y    
Special Stock Plan
      
Weighted Average assumptions, weighted average expected life and estimated fair value of options      
Weighted average volatility (as a percent)     34.10%
Expected dividend yield (as a percent)     1.50%
Risk-free rate (as a percent)     2.00%
Weighted average expected life (in years)     5.60
Weighted average estimated fair value per share (in dollars per share)     $ 11.82
All Other Option Plans
      
Weighted Average assumptions, weighted average expected life and estimated fair value of options      
Weighted average volatility (as a percent) 26.10% 28.50% 32.00%
Expected dividend yield (as a percent) 1.30% 1.60% 1.50%
Risk-free rate (as a percent) 2.20% 3.00% 2.60%
Weighted average expected life (in years) 5.5 6.10 6.50
Weighted average estimated fair value per share (in dollars per share) $ 10.92 $ 10.37 $ 12.34
Incentive compensation plans | Employee Stock Option
      
Weighted Average assumptions, weighted average expected life and estimated fair value of options      
Granted (in dollars per share) $ 53 $ 38 $ 37
Stock Options      
Granted (in shares) 80 143 550
Hewitt Associates, Inc (Hewitt)
      
Stock Options      
Outstanding at end of period (in shares) 1,200    
Shares available for grant (in shares)   4,500