Quarterly report pursuant to Section 13 or 15(d)

Stock-based Compensation - Purchase Plan (Details)

v3.7.0.1
Stock-based Compensation - Purchase Plan (Details) - Purchase plan
$ in Millions
6 Months Ended
Jun. 30, 2017
USD ($)
item
shares
Jun. 30, 2016
Additional disclosures    
Award offering period 24 months  
Number of purchase periods per award offering period | item 4  
Award purchase period 6 months  
Purchase price expressed as a percentage of fair market value of common stock on the purchase date 85.00%  
Purchase price expressed as a percentage of fair market value of common stock on the first day of the offering period 85.00%  
Total incremental fair value for the Purchase Plan reset | $ $ 1.0  
Shares reserved for future issuance | shares 2,324,942  
Weighted-average assumptions relating to Purchase Plan    
Risk-free interest rate (as a percent) 0.50% 0.70%
Expected term (in years) 1 year 6 months 1 year 9 months 18 days
Dividend yield (as a percent) 0.00% 0.00%
Expected volatility (as a percent) 63.10% 61.50%