Quarterly report pursuant to Section 13 or 15(d)

Share-Based Compensation - Additional Information (Detail)

v2.4.0.8
Share-Based Compensation - Additional Information (Detail) (USD $)
In Millions, except Per Share data, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Sep. 30, 2013
Sep. 30, 2012
Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation expense $ 6.6 $ 8.4 $ 21.9 $ 20.8  
Unrecognized compensation cost on non-vested stock awards 30.3   30.3    
Unrecognized compensation cost on non-vested stock awards, weighted-average period of recognition     1 year 1 month 6 days    
Total intrinsic value of awards exercised for options and SARs 0.1 2.3 0.3 96.6  
Total vesting date fair value of stock units 0.4 1.1 7.2 24.1  
Unrealized excess tax benefits $ 29.1   $ 29.1   $ 25.9
SARs [Member]
         
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Weighted-average grant date fair value of SARs granted $ 0.00 $ 16.54 $ 11.85 $ 15.35