Convertible Preferred Stock (Tables)
 6 Months Ended
Jun. 30, 2015
Temporary Equity, Other Disclosures [Abstract]  
Schedule of issuances of convertible preferred stock
The following table summarizes the issuances of convertible preferred stock subject to conversion as of the IPO completion:
 
Number of Shares
Authorized
 
Number of Shares
Outstanding
 
Original Issue and
Conversion Price
per Share
Series A convertible preferred stock
2,486,507

 
2,383,745

 
$
0.582

Series B convertible preferred stock
3,649,368

 
3,649,368

 
$
0.84656

Series C convertible preferred stock
5,406,501

 
5,406,501

 
$
1.4798

Series D convertible preferred stock
3,409,250

 
3,409,210

 
$
3.8132

Total convertible preferred stock
14,951,626

 
14,848,824

 
 
Summary of activity for the convertible preferred stock
The following table presents a summary of activity for the convertible preferred stock issued and outstanding for the six months ended June 30, 2015 (in thousands):
 
Convertible Preferred Stock
 
Series A
 
Series B
 
Series C
 
Series D
 
Total Amount
Balance, December 31, 2014
$
1,387

 
$
3,089

 
$
8,000

 
$
13,000

 
$
25,476

Conversion to common stock upon IPO
(1,387
)
 
(3,089
)
 
(8,000
)
 
(13,000
)
 
(25,476
)
Balance, June 30, 2015
$
—

 
$
—

 
$
—

 
$
—

 
$
—