XML 26 R18.htm IDEA: XBRL DOCUMENT v3.19.3
Marketable Securities (Tables)
9 Months Ended
Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]  
Fair value of marketable securities, by type
The following table summarizes the fair value of our marketable securities, by level within the fair value hierarchy, as of each period end:
September 30, 2019December 31, 2018
Level 1Level 2TotalLevel 1Level 2Total
U.S. Treasury notes and bonds$—  $—  $—  $5,034,955  $—  $5,034,955  
Corporate bonds—  —  —  —  2,504,551  2,504,551  
Commercial paper—  2,265,8392,265,839  —  —  —  
Short-term cash investments—  —  —  —  751,173  751,173  
Total fair value of marketable securities$—  $2,265,839  $2,265,839  $5,034,955  $3,255,724  $8,290,679