Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation - Additional Information (Detail)

v2.4.0.6
Share-Based Compensation - Additional Information (Detail) (USD $)
In Millions, except Share data, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Sep. 30, 2012
Sep. 30, 2011
Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense $ 8.4 $ 6.1 $ 20.8 $ 17.2  
Unrecognized compensation cost on nonvested stock awards 58.5   58.5    
Unrecognized compensation cost on nonvested stock awards, weighted-average period of recognition     1 year 7 months 6 days    
Outstanding market and performance condition SARs 387,100   387,100   717,600
Outstanding and exercisable market condition SARs 5,781,000 [1]   5,781,000 [1]    
Weighted-average grant date fair value of granted           
Total intrinsic value of awards exercised for options and SARs 2.3 36.8 96.6 100.9  
Total vesting date fair value of stock units 1.1 1.6 24.1 19.5  
Excess tax benefit $ 26.5   $ 26.5   $ 20.6
Market Condition Awards
         
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Outstanding market and performance condition SARs 1,500,000   1,500,000   1,500,000
Outstanding and exercisable market condition SARs 1,500,000   1,500,000    
Market and Performance Condition Awards [Member]
         
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Outstanding market and performance condition SARs 900,000   900,000   900,000
SARs
         
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Weighted-average grant date fair value of granted $ 16.54 $ 17.40 $ 15.35 $ 19.63  
[1] Includes 1.5 million market condition SARs.