XML 155 R59.htm IDEA: XBRL DOCUMENT v2.4.0.8
Share-Based Compensation - Performance Share Units - Additional Information (Detail) (USD $)
In Millions, except Share data, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2013
Jun. 30, 2012
Jun. 30, 2013
Jun. 30, 2012
Jun. 30, 2011
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Share-based compensation (income) expense $ 7.1 $ 7.4 $ 11.1 $ 14.8  
Performance Share Unit Awards
         
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Granted, Shares     485,000    
Equity instruments other than options, payout range, minimum     242,500   117,500
Equity instruments other than options, payout range, maximum     485,000 233,000  
Equity instruments other than options, percentage of expected payout         50.00%
Share-based compensation (income) expense 0.7 0.5 1.1 1.0  
Unrecognized share-based compensation cost $ 5.0   $ 5.0    
Unrecognized compensation expense, weighted-average period of recognition     2 years 2 months 12 days