v2.4.0.6
Stock-Based Compensation (Details) (USD $)
12 Months Ended
Dec. 31, 2012
plan
Dec. 31, 2011
Dec. 31, 2010
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]      
Number of share-based compensation plans covering employees, officers and directors 5    
Number of share-based compensation plans for executive officers 1    
Number of share-based compensation plans for directors 2    
Stock-Based Compensation      
Unrecognized compensation cost related to nonvested awards $ 18,200,000    
Unrecognized compensation cost related to nonvested awards assumed in the NHP acquisition 100,000    
Weighted average period over which cost is recognized (in years) 2 years 8 months 12 days    
Fair value assumptions of stock options using Black-Scholes option pricing model      
Expiration period of stock options (in years) 10 years    
Employee Benefit Plan      
Maximum 401(K) plan contribution by employer as a percent of employee's salary 3.50%    
Aggregate employer 401(K) plan contribution during the period 768,000 267,000 200,000
Minimum
     
Stock-Based Compensation      
Vesting period (in years) 2 years    
Maximum
     
Stock-Based Compensation      
Vesting period (in years) 3 years    
Executive Deferred Stock Compensation Plan
     
Stock-Based Compensation      
Number of shares reserved for issuance 500,000    
Number of shares available for future issuance 500,000    
Nonemployee Directors' Deferred Stock Compensation Plan
     
Stock-Based Compensation      
Number of shares reserved for issuance 500,000    
Number of shares available for future issuance 432,070    
Stock Options
     
Stock-Based Compensation      
Compensation cost 4,400,000 4,200,000 3,100,000
Unrecognized compensation cost related to nonvested awards 1,600,000    
Weighted average period over which cost is recognized (in years) 1 year 2 months 12 days    
Proceeds from options exercised 21,500,000 2,500,000 10,900,000
Fair value assumptions of stock options using Black-Scholes option pricing model      
Risk-free interest rate, maximum (as a percent) 1.39% 2.78% 3.45%
Risk-free interest rate, minimum (as a percent) 0.68% 1.22% 2.00%
Dividend yield (as a percent) 6.75% 6.75% 6.75%
Volatility factors of the expected market price for our common stock, maximum (as a percent) 42.90% 44.30% 44.60%
Volatility factors of the expected market price for our common stock, minimum (as a percent) 35.90% 35.70% 37.10%
Stock Option, Shares      
Outstanding at the beginning of the period (in shares) 2,047,005,000    
Granted (in shares) 459,015,000    
Options exercised (in shares) (596,021,000)    
Outstanding at the end of the period (in shares) 1,909,999,000 2,047,005,000  
Exercisable at the end of the period (in shares) 1,488,579,000    
Stock Option, Weighted Average Exercise Price      
Outstanding at the beginning of the period (in dollars per share) $ 42.10    
Options granted (in shares) $ 55.58    
Options exercised (in dollars per share) $ 36.14    
Outstanding at the end of the period (in dollars per share) $ 47.20 $ 42.10  
Exercisable at the end of the period (in dollars per share) $ 44.96    
Stock Option, Weighted Average Remaining Contractual Life (years)      
Outstanding at the end of the period (in years) 6 years 10 months 24 days    
Exercisable at the end of the period (in years) 6 years 3 months 18 days    
Stock Option, Intrinsic Value      
Outstanding at the end of the period 33,469,000    
Exercisable at the end of the period 29,410,000    
Nonvested Stock Options, Shares      
Nonvested stock options at the beginning of the period (in shares) 361,040,000    
Granted (in shares) 459,015,000    
Vested (in shares) (398,629,000)    
Nonvested stock options at the end of the period (in shares) 421,426,000 361,040,000  
Nonvested Stock Options, Weighted Average Grant Date Fair Value      
Nonvested stock options at the beginning of the period (in dollars per share) $ 10.76    
Granted (in dollars per share) $ 10.54    
Vested (in dollars per share) $ 10.40    
Nonvested stock options at the end of the period (in dollars per share) $ 10.86 $ 10.76  
Stock Options | Minimum
     
Fair value assumptions of stock options using Black-Scholes option pricing model      
Weighted average expected life of options, maximum (in years) 4 years 3 months 4 years 3 months 4 years 3 months
Stock Option, Range of Exercise Prices      
Range of exercise price, low end of range (in dollars per share) $ 11.86 $ 11.45  
Exercise price range, options granted (in dollars per share) $ 55.13    
Exercise price range, options assumed from NHP (in dollars per share) $ 0.00    
Exercise price range, options excercised (in dollars per share) $ 11.45    
Exercise price range, options excercisable (in dollars per share) $ 11.86    
Stock Options | Maximum
     
Fair value assumptions of stock options using Black-Scholes option pricing model      
Weighted average expected life of options, maximum (in years) 7 years 7 years 7 years
Stock Option, Range of Exercise Prices      
Range of exercise price, high end of range (in dollars per share) $ 57.19 $ 57.19  
Exercise price range, options granted (in dollars per share) $ 55.69    
Exercise price range, options assumed from NHP (in dollars per share) $ 0.00    
Exercise price range, options excercised (in dollars per share) $ 57.19    
Exercise price range, options excercisable (in dollars per share) $ 57.19    
Restricted Stock
     
Nonvested Restricted Stock and Restricted Stock Units, Shares      
Nonvested at the beginning of the period (in shares) 592,198,000    
Granted (in shares) 276,484,000    
Vested (in shares) (271,224,000)    
Forfeited (in shares) (5,574,000)    
Nonvested at the end of the period (in shares) 591,884,000    
Nonvested Restricted Stock and Restricted Stock Units, Weighted Average Grant Date Fair Value      
Nonvested at the beginning of the period (in dollars per share) $ 50.09    
Granted (in dollars per share) $ 55.61    
Vested (in dollars per share) $ 50.12    
Forfeited (in dollars per share) $ 49.36    
Nonvested at the end of the period (in dollars per share) $ 52.66    
Restricted Stock Units
     
Nonvested Restricted Stock and Restricted Stock Units, Shares      
Nonvested at the beginning of the period (in shares) 33,289,000    
Granted (in shares) 4,112,000    
Vested (in shares) (30,576,000)    
Nonvested at the end of the period (in shares) 6,825,000    
Nonvested Restricted Stock and Restricted Stock Units, Weighted Average Grant Date Fair Value      
Nonvested at the beginning of the period (in dollars per share) $ 50.04    
Granted (in dollars per share) $ 55.13    
Vested (in dollars per share) $ 50.65    
Nonvested at the end of the period (in dollars per share) $ 50.34    
Restricted Stock Units | Minimum
     
Stock-Based Compensation      
Vesting period (in years) 2 years    
Restricted Stock Units | Maximum
     
Stock-Based Compensation      
Vesting period (in years) 5 years    
Restricted Stock Units | General and administrative expenses
     
Stock-Based Compensation      
Compensation cost $ 16,400,000 $ 15,100,000 $ 11,000,000
Employee and Director Stock Purchase Plan
     
Stock-Based Compensation      
Number of shares reserved for issuance 2,500,000    
Number of shares available for future issuance 2,446,155    
Number of shares purchased 53,845    
Employee and Director Stock Purchase Plan | Minimum
     
Stock-Based Compensation      
Purchase price of common stock shares with respect to the employee tax-favored portion of the plan (as a percent) 90.00%    
Purchase price of common stock shares with respect to the additional employee and director portion of the plan (as a percent) 95.00%    
2012 Incentive Plan
     
Stock-Based Compensation      
Number of shares reserved for future issuance 8,836,614    
2012 Incentive Plan | Stock Options
     
Stock-Based Compensation      
Number of shares reserved for issuance 1,835,325    
2012 Incentive Plan | Restricted Stock or Restricted Stock Units
     
Stock-Based Compensation      
Number of shares reserved for issuance 595,480    
2012 Incentive Plan | Shares under 2006 Incentive Plan
     
Stock-Based Compensation      
Number of shares reserved for issuance 1,336,614    
2012 Incentive Plan | New Shares
     
Stock-Based Compensation      
Number of shares reserved for issuance 7,500,000