Equity Compensation Plans - Restricted Stock and RSUs (Details) - Restricted stock and restricted stock units - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Changes in unvested awards
Nonvested at the beginning of the period (in shares)	465,000
Granted (in shares)	254,281	161,500
Vested (in shares)	(167,000)
Nonvested at the end of the period (in shares)	552,281	465,000
Weighted Average Grant Date Fair Value
Nonvested at the beginning of the period (in dollars per share)	$ 7.79
Granted (in dollars per share)	13.98
Vested (in dollars per share)	5.60
Nonvested at the end of the period (in dollars per share)	$ 11.31	$ 7.79
Additional information
Total unrecognized compensation cost of restricted awards	$ 3.0
Expected weighted-average period for recognition of unrecognized compensation	1 year 9 months 18 days

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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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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- Definition

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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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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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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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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