Stock-Based Compensation - Restricted Stock Units (Details) $ / shares in Units, $ in Millions	3 Months Ended
Mar. 31, 2021 USD ($) $ / shares shares
Weighted Average Exercise Price Per Share
Unrecognized stock-based compensation expense \| $	$ 2.0
Unrecognized compensation expense, weighted-average period expected to be recognized	2 years 8 months 12 days
Restricted stock units
Number of Restricted Stock Units
Balance, beginning of period \| shares	416,742
Granted \| shares	236,605
Vested \| shares	(136,709)
Cancelled/forfeited \| shares	(31,626)
Balance, end of period \| shares	485,012
Weighted Average Exercise Price Per Share
Balance, beginning of period (price per share) \| $ / shares	$ 4.89
Granted (price per share) \| $ / shares	5.71
Vested (price per share) \| $ / shares	5.16
Cancelled/forfeited (price per share) \| $ / shares	4.12
Balance, end of period (price per share) \| $ / shares	$ 5.26
2016 Employee Incentive Plan \| Restricted stock units
Weighted Average Exercise Price Per Share
Unrecognized stock-based compensation expense \| $	$ 1.7
Unrecognized compensation expense, weighted-average period expected to be recognized	1 year 6 months

n/a

No definition available.

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- Definition

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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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 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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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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- Definition

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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Net number of non-option equity instruments granted to participants.

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Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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