Fair Value Measurements of Financial Instruments - Schedule of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financial assets - available-for-sales securities
Total financial assets - available-for-sales securities	$ 25,457	$ 21,920
Money Market Funds
Financial assets - available-for-sales securities
Total financial assets - available-for-sales securities	2,544	2,027
Commercial Paper
Financial assets - available-for-sales securities
Total financial assets - available-for-sales securities	1,749	6,962
Corporate Bonds
Financial assets - available-for-sales securities
Total financial assets - available-for-sales securities	21,164	12,931
Fair Value Measurements Recurring
Financial assets - available-for-sales securities
Total financial assets - available-for-sales securities	25,457	21,920
Fair Value Measurements Recurring | Money Market Funds
Financial assets - available-for-sales securities
Total financial assets - available-for-sales securities	2,544	2,027
Fair Value Measurements Recurring | Commercial Paper
Financial assets - available-for-sales securities
Total financial assets - available-for-sales securities	1,749	6,962
Fair Value Measurements Recurring | Corporate Bonds
Financial assets - available-for-sales securities
Total financial assets - available-for-sales securities	21,164	12,931
Fair Value Measurements Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets - available-for-sales securities
Total financial assets - available-for-sales securities	2,544	2,027
Fair Value Measurements Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Money Market Funds
Financial assets - available-for-sales securities
Total financial assets - available-for-sales securities	2,544	2,027
Fair Value Measurements Recurring | Significant Other Observable Inputs (Level 2)
Financial assets - available-for-sales securities
Total financial assets - available-for-sales securities	22,913	19,893
Fair Value Measurements Recurring | Significant Other Observable Inputs (Level 2) | Commercial Paper
Financial assets - available-for-sales securities
Total financial assets - available-for-sales securities	1,749	6,962
Fair Value Measurements Recurring | Significant Other Observable Inputs (Level 2) | Corporate Bonds
Financial assets - available-for-sales securities
Total financial assets - available-for-sales securities	$ 21,164	$ 12,931