Fair Value Measurements - Fair Value of Liabilities Measured on a Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Fair value of liabilities measured on a recurring basis
Total fair value	$ 4,086	$ 3
Level 3
Fair value of liabilities measured on a recurring basis
Total fair value	4,086	3
Warrant liability
Fair value of liabilities measured on a recurring basis
Warrant liability	4,086	3
Warrant liability | Level 3
Fair value of liabilities measured on a recurring basis
Warrant liability	$ 4,086	$ 3