The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Price of a single share of a number of saleable stocks of a company.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Number of shares issued in lieu of cash for services contributed to the entity. Number of shares includes, but is not limited to, shares issued for services contributed by vendors and founders.

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Equity Incentive Plans - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2021	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from ESPP		$ 341	$ 459	$ 819	$ 834
Board of directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock for services (shares)				25,989
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued under ESPP	500,000
Purchase price (in dollars per share)	$ 1.21
Proceeds from ESPP	$ 600
PRSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of awards granted (shares)				0
Awards outstanding (shares)		0		0