XML 85 R38.htm IDEA: XBRL DOCUMENT v3.19.3
Fair Value of Financial Instruments - (Details) - USD ($)
Sep. 30, 2019
Dec. 31, 2018
Dec. 31, 2017
Fair value of the Company's financial assets      
Assets transferred from level 1 to level 2 $ 0 $ 0 $ 0
Assets transferred from level 2 to level 1 $ 0 0 0
Carrying Amount      
Fair value of the Company's financial assets      
Money market funds (cash equivalents)   5,000,000 1,000,000
Fair Value      
Fair value of the Company's financial assets      
Money market funds (cash equivalents)   5,000,000 1,000,000
Fair Value | Quoted Prices in Active Markets (Level 1)      
Fair value of the Company's financial assets      
Money market funds (cash equivalents)   $ 5,000,000 $ 1,000,000