Stockholders' Equity - Summary of RSU Activity (Details)	9 Months Ended
Sep. 30, 2021 USD ($) $ / shares shares
2013 Equity Incentive Plan
Restricted Stock Units information
Period for unrecognized compensation expense related to unvested options yet has not been recognized	2 years 1 month 6 days
RSU
Restricted Stock Units information
Vesting period	4 years
RSU \| 2013 Equity Incentive Plan
NUMBER OF SHARES
Unvested at beginning of period \| shares	192,533
Granted \| shares	444,613
Forfeited \| shares	(49,754)
Vested \| shares	(189,792)
Unvested at end of period \| shares	397,600
WEIGHTED-AVERAGE GRANT DATE FAIR VALUE
Unvested at beginning of period \| $ / shares	$ 4.53
Granted \| $ / shares	3.72
Forfeited \| $ / shares	3.85
Vested \| $ / shares	4.53
Unvested at end of period \| $ / shares	$ 3.71
RSU \| 2013 Equity Incentive Plan \| Non-executive employees
Restricted Stock Units information
Unrecognized compensation expense related to unvested service RSUs \| $	$ 1,204,644
Period for unrecognized compensation expense related to unvested options yet has not been recognized	3 years 2 months 12 days

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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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 weighted average fair value at grant date for nonvested equity-based awards issued 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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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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