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Stock-Based Compensation - Schedule of Fair Value Option Award Estimated on the Date of Grant Using the Black-Scholes Option-Pricing Model (Detail)
3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected dividend yield 0.00% 0.00%
Expected volatility   50.90%
Risk-free interest rate   1.20%
Expected term   7 years
Expected forfeiture rate 5.00% 5.00%
Minimum [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected volatility 66.70%  
Risk-free interest rate 2.10%  
Expected term 6 years  
Maximum [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected volatility 66.90%  
Risk-free interest rate 2.30%  
Expected term 6 years 3 months