Annual report pursuant to Section 13 and 15(d)

Incentive Compensation Plan - Additional Information (Detail)

v2.4.0.6
Incentive Compensation Plan - Additional Information (Detail)
12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Compensation Plan [Line Items]      
Percentage of RSUs affected by performance 100.00% 100.00% 100.00%
Expected vesting date Dec. 15, 2014 Dec. 15, 2013  
Minimum
     
Compensation Plan [Line Items]      
Expected volatility 33.00%    
Expected dividend yield 0.00%    
Correlation of movement of total shareholder return maximum range (67.00%)    
Maximum
     
Compensation Plan [Line Items]      
Expected volatility 74.00%    
Expected dividend yield 2.50%    
Correlation of movement of total shareholder return maximum range 94.00%    
LIBOR
     
Compensation Plan [Line Items]      
Risk-free interest rate, minimum 0.15%    
Risk-free interest rate, maximum 0.72%    
Earnings Per Share Targets
     
Compensation Plan [Line Items]      
Restricted stock units earning per share, minimum 0.00%    
Restricted stock units earning per share, maximum 100.00%    
Earnings Per Share Targets | Current year
     
Compensation Plan [Line Items]      
Percentage of RSUs affected by performance 70.00%    
Total Shareholder Return
     
Compensation Plan [Line Items]      
Restricted stock units earning per share, minimum 0.00%    
Restricted stock units earning per share, maximum 150.00%    
Total Shareholder Return | Current year
     
Compensation Plan [Line Items]      
Percentage of RSUs affected by performance 10.00%    
Total Shareholder Return | 2013
     
Compensation Plan [Line Items]      
Percentage of RSUs affected by performance 10.00%    
Total Shareholder Return | 2014
     
Compensation Plan [Line Items]      
Percentage of RSUs affected by performance 10.00%