Annual report pursuant to Section 13 and 15(d)

STOCK-BASED COMPENSATION - Additional Information (Detail)

v2.4.0.6
STOCK-BASED COMPENSATION - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2011
OptionPlan
Dec. 31, 2010
Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of active share-based award plan 1    
Total income tax benefit recognized for stock-based compensation expense $ 8.7 $ 7.8 $ 6.9
Excess tax benefits from stock-based compensation plans 1.2 3.5 1.3
Excess tax benefits from stock-based compensation plans (1.2) (3.5) (1.3)
Stock options vesting percentage for each year of completed service 33.00%    
Stock options expiration periods 10 years    
Stock options valuation method description We use the binomial model to calculate the fair value of stock options granted on or after January 1, 2006.    
Stock Options
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total intrinsic value of stock options exercised 9.9 14.7 5.1
Total unrecognized compensation cost 7.7    
Total unrecognized compensation cost, weighted-average period of recognition 1.5    
Stock Options | Maximum
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock awards vesting periods 3 years    
Nonvested Stock
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Total weighted-average fair value on the vesting date 12.1 10.3 6.5
Total weighted-average fair value on the date of grant 11.7 12.1 7.9
Total unrecognized compensation cost $ 17.1    
Total unrecognized compensation cost, weighted-average period of recognition 1.9    
Nonvested Stock | Maximum
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock awards vesting periods 3 years    
Nonvested Stock | Minimum
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock awards vesting periods 1 year