Term Notes - Schedule of Current and Noncurrent Debt and Net Discount or Premium Balances (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument Periodic Payment [Abstract]
Principal amount of term note	$ 16,500	$ 16,500
Net premium associated with accretion of final payment, and other debt issuance costs	476	119
Term note, current and noncurrent	16,976	16,619
Less term note, current portion	(2,750)	(3,300)
Term note, noncurrent portion	$ 14,226	$ 13,319

Face (par) amount of debt instrument at time of issuance.

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