Stockholders' Equity (Additional Information) (Details) (USD $)
0 Months Ended 9 Months Ended
Jul. 10, 2014
Sep. 30, 2014
Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Proceeds from issuance of common stock, net of issuance costs $ 23,400,000 $ 23,439,000 $ 19,973,000
Aggregate intrinsic value of options exercised   2,700,000 44,000
Stock Options
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Compensation costs not yet recognized   13,400,000  
Period for recognizing costs   3 years 1 month 6 days  
IPO | Common Stock
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock issued (in shares) 4,200,000    
Gross proceeds from stock offering $ 25,200,000