Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Research and development	$ 921	$ 448
Other	649	699
Insurance	229	217
VAT receivables	1	26
Total	$ 1,800	$ 1,390