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Shared-Based Payments - Schedule of Fair Value Option Award Estimated on the Date of Grant Using the Black-Scholes Option-Pricing Model (Detail)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected dividend yield   0.00% 0.00%
Expected volatility   51.00% 62.00%
Risk-free interest rate   1.18% 1.35%
Expected term 7 years 7 years 7 years
Expected forfeiture rate   5.57% 5.58%
Minimum [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected dividend yield 0.00%    
Expected volatility 53.00%    
Risk-free interest rate 1.24%    
Expected forfeiture rate 5.06%    
Maximum [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected volatility 67.00%    
Risk-free interest rate 2.19%    
Expected forfeiture rate 5.57%