XML 69 R45.htm IDEA: XBRL DOCUMENT v3.19.1
Cash, Cash Equivalents and Short-Term Investments - Schedule of Contractual Maturities of Short-term Investments (Details) - USD ($)
Dec. 31, 2018
Dec. 31, 2017
Investments Debt And Equity Securities [Abstract]    
Due within one year $ 20,168,981  
Total $ 20,168,981 $ 21,287,064