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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 cost to be recognized for option under share-based payment arrangement.

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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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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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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of fully vested and expected to vest exercisable options that may be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted-average exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for fully vested and expected to vest exercisable or convertible options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Fair value of options vested. Excludes equity instruments other than options, for example, but not limited to, share units, stock appreciation rights, restricted stock.

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Number of share options (or share units) exercised during the current period.

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Stock Incentive Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Shares
Outstanding, beginning of period (in shares)			785,832
Granted (in shares)			548,500
Cancelled or forfeited (in shares)			(32,589)
Expired (in shares)			(481)
Outstanding, end of period (in shares)	1,301,262		1,301,262		785,832
Vested and exercisable (in shares)	426,375		426,375
Weighted-Average Exercise Price
Outstanding, beginning of period (in dollars per share)			$ 16.48
Granted (in dollars per share)			5.47
Cancelled or forfeited (in dollars per share)			26.59
Expired (in dollars per share)			32.10
Outstanding at end of year (in dollars per share)	$ 11.58		11.58		$ 16.48
Vested and Exercisable (in dollars per share)	$ 23.70		$ 23.70
Weighted Average Remaining Contractual Term (years)
Outstanding			8 years 6 months 4 days		8 years 1 month 17 days
Vested and Exercisable			6 years 11 months 16 days
Aggregate Intrinsic Value
Outstanding	$ 1,180		$ 1,180		$ 470
Vested and Exercisable	219		$ 219
Stock options
Stock Incentive Plans
Exercised (in shares)			0	0
Aggregate fair value of options vested	$ 300	$ 400	$ 800	$ 800
Weighted average grant date fair value of options granted (in dollars per share)	$ 4.00	$ 4.00	$ 3.64	$ 3.06
Unrecognized compensation expense related to unvested stock option awards	$ 3,000		$ 3,000
Weighted-average amortization period over which cost is expected to be recognized			2 years 9 months 18 days