v3.10.0.1
Stockholders' Equity (Details) - USD ($)
$ in Thousands
 9 Months Ended
May 22, 2018
Sep. 30, 2018
Sep. 30, 2017
Jan. 01, 2018
Dec. 31, 2017
Jan. 01, 2017
Stockholders' Equity            
Proceeds from issuance of common stock, net of offering costs   $ 330,862 $ 189,917      
Authorized shares of capital stock (in shares)   205,000,000        
Authorized shares of common stock (in shares)   200,000,000     200,000,000  
Authorized shares of preferred stock (in shares)   5,000,000     5,000,000  
Shares of common stock reserved for future issuance            
Outstanding stock options (in shares)   4,097,480        
Possible future issuance under 2014 Equity Incentive Plan (in shares)   6,139,677        
Outstanding restricted stock units (in shares)   1,217,161        
Available for future issuance under employee stock purchase plan (in shares)   977,517        
Total shares of common stock reserved for future issuance (in shares)   12,431,835        
Equity Incentive Plan 2014 | Stock options            
Shares of common stock reserved for future issuance            
Possible future issuance under 2014 Equity Incentive Plan (in shares)       2,625,292   2,357,579
Common Stock            
Stockholders' Equity            
Shares issued (in shares) 3,833,334 3,833,334        
Proceeds from issuance of common stock, net of offering costs $ 330,800          
Common Stock | Underwriters' over-allotment option            
Stockholders' Equity            
Shares issued (in shares) 500,000