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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)
6 Months Ended
Jun. 30, 2014
Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected dividend yield 0.00% 0.00%
Expected volatility 67.00% 58.00%
Risk-free interest rate   1.80%
Expected term 6 years 3 months 7 years
Expected forfeiture rate 5.00% 5.00%
Minimum [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Risk-free interest rate 2.09%  
Maximum [Member]
   
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Risk-free interest rate 2.32%