Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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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 noncash expense for share-based payment arrangement.

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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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Stock-Based Compensation - Restricted Stock Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restricted Stock Activity, Weighted-Average Grant Date Fair Value
Unrecognized compensation expense		$ 3,500
Weighted average remaining period over which unrecognized compensation expense will be recognized		2 years 2 months 12 days
Share-based compensation		$ 3,641	$ 3,845	$ 5,674
Restricted stock units
Restricted Stock Activity, Number of Shares
Nonvested shares, Beginning Balance		193,625
Granted		365,845
Cancelled		(28,895)
Vested		(176,572)
Nonvested shares, Ending Balance		354,003	193,625
Restricted Stock Activity, Weighted-Average Grant Date Fair Value
Nonvested shares, Weighted Average Grant Date Fair Value, Beginning Balance		$ 3.14
Granted, Weighted-Average Grant Date Fair Value		2.65
Cancelled, Weighted-Average Grant Date Fair Value		2.75
Vested, Weighted-Average Grant Date Fair Value		3.95
Nonvested shares, Weighted Average Grant Date Fair Value, Ending Balance		$ 2.27	$ 3.14
Unrecognized compensation expense		$ 700
Weighted average remaining period over which unrecognized compensation expense will be recognized		1 year 10 months 24 days
Restricted stock units \| 2013 Stock Incentive Plan
Restricted Stock Activity, Number of Shares
Granted		128,170
Market/Performance-based Awards
Restricted Stock Activity, Number of Shares
Granted		556,888
Cancelled		(7,570)
Nonvested shares, Ending Balance		549,318
Restricted Stock Activity, Weighted-Average Grant Date Fair Value
Granted, Weighted-Average Grant Date Fair Value		$ 1.54
Cancelled, Weighted-Average Grant Date Fair Value		1.54
Nonvested shares, Weighted Average Grant Date Fair Value, Ending Balance		$ 1.54
Weighted average remaining period over which unrecognized compensation expense will be recognized		1 year 6 months
Requisite service period (in years)	2 years 4 months 9 days
Share-based compensation		$ 200
Unrecognized compensation expense related to the restricted stock units		700
Additional compensation expense as a result of meeting certain achievements		$ 300