Fair Value of Financial Instruments - Schedule of Financial Assets and Liabilities Measured at Fair Value On a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Liabilities:
Warrant liabilities, noncurrent	$ 399	$ 0
Fair Value, Recurring
Liabilities:
Derivative liability	11,938
Warrant liabilities, noncurrent	399
Total liabilities	12,337
Fair Value, Recurring | Level 1
Liabilities:
Derivative liability	0
Warrant liabilities, noncurrent	0
Total liabilities	0
Fair Value, Recurring | Level 2
Liabilities:
Derivative liability	0
Warrant liabilities, noncurrent	399
Total liabilities	399
Fair Value, Recurring | Level 3
Liabilities:
Derivative liability	11,938
Warrant liabilities, noncurrent	0
Total liabilities	$ 11,938