XML 131 R84.htm IDEA: XBRL DOCUMENT v2.4.0.8
Assumptions used in Valuation Performance Awards Granted (Detail) (Performance Based Restricted Stock [Member], USD $)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Assumptions      
Expected volatility   37.00% 51.00%
Risk-free interest rate   0.30% 1.04%
Stock beta   0.913 1.006
Expected life 3 years 3 years 3 years
Minimum [Member]
     
Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items]      
Fair value per share at grant date $ 39.50 $ 54.90 $ 38.94
Assumptions      
Expected volatility 31.00%    
Risk-free interest rate 0.41%    
Stock beta 0.907    
Maximum [Member]
     
Share based Compensation Arrangement by Share based Payment Award, Fair Value Assumptions, Method Used [Line Items]      
Fair value per share at grant date $ 68.01 $ 63.64 $ 64.89
Assumptions      
Expected volatility 32.00%    
Risk-free interest rate 0.62%    
Stock beta 0.908