XML 31 R19.htm IDEA: XBRL DOCUMENT v3.5.0.2
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - STOCK OPTIONS AND EMPLOYEE STOCK PURCHASE PLAN (Details)
9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Stock options    
Stock-Based Compensation    
Vesting period of awards 4 years  
Assumptions used to estimate fair value of awards    
Dividend yield (as a percent) 0.00% 0.00%
Expected volatility range, minimum (as a percent) 88.80% 87.40%
Expected volatility range, maximum (as a percent) 89.00% 88.40%
Risk-free interest rate range, minimum (as a percent) 1.21% 1.68%
Risk-free interest rate range, maximum (as a percent) 1.38% 1.71%
Expected term 5 years 6 months 5 years 6 months
Employee Stock Purchase Plan    
Assumptions used to estimate fair value of awards    
Dividend yield (as a percent) 0.00% 0.00%
Expected volatility range, minimum (as a percent) 64.10% 65.40%
Expected volatility range, maximum (as a percent) 68.40% 139.20%
Risk-free interest rate range, minimum (as a percent) 0.28% 0.11%
Risk-free interest rate range, maximum (as a percent) 0.45% 0.28%
Employee Stock Purchase Plan | Minimum    
Assumptions used to estimate fair value of awards    
Expected term 6 months 6 months
Employee Stock Purchase Plan | Maximum    
Assumptions used to estimate fair value of awards    
Expected term 12 months 12 months
Service-based restricted stock awards    
Stock-Based Compensation    
Vesting period of awards 4 years