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
0 Months Ended 3 Months Ended 6 Months Ended
Jun. 30, 2014
Jun. 30, 2014
Jun. 30, 2013
Jun. 30, 2014
Jun. 30, 2013
Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]            
Share-based compensation expense   $ 12.4 $ 7.4 $ 23.4 $ 15.3  
Unrecognized compensation cost on non-vested stock awards 74.7 74.7   74.7    
Unrecognized compensation cost on non-vested stock awards, weighted-average period of recognition 1 year 8 months 12 days          
Weighted-average grant date fair value of SARs granted   $ 25.99 $ 12.68 $ 26.02 $ 11.85  
Total intrinsic value of awards exercised for options and SARs   20.1 0 35.0 0.3  
Total vesting date fair value of stock units   0.3 2.5 8.5 6.8  
Unrealized excess tax benefits $ 18.2 $ 18.2   $ 18.2   $ 15.4