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Fair value measurements (Tables)
3 Months Ended
Mar. 31, 2017
Fair Value Disclosures [Abstract]  
Summary of Cash Equivalents and Marketable Securities Measured at Fair Value on a Recurring Basis
The following tables summarize the cash equivalents and marketable securities measured at fair value on a recurring basis as of March 31, 2017 and December 31, 2016:
 
Level 1
 
Level 2
 
Level 3
 
Balance as of
March 31, 2017
Cash equivalents
$
11,115,898

 
$

 
$

 
$
11,115,898

Marketable securities:
 
 
 
 
 
 
 
Corporate debt securities

 
3,102,128

 

 
3,102,128

Commercial paper

 
4,594,668

 

 
4,594,668

U.S. government agency securities

 
24,046,290

 

 
24,046,290

 
$
11,115,898

 
$
31,743,086

 
$

 
$
42,858,984



 
Level 1
 
Level 2
 
Level 3
 
Balance as of December 31, 2016
Cash equivalents
$
11,681,074

 
$

 
$

 
$
11,681,074

Marketable securities:
 
 
 
 
 
 
 
Corporate debt securities

 
1,518,240

 

 
1,518,240

Commercial paper

 
6,081,202

 

 
6,081,202

U.S. government agency securities

 
31,059,491

 

 
31,059,491

 
$
11,681,074

 
$
38,658,933

 
$

 
$
50,340,007