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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 options awarded to employees as compensation.

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Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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For presentations that combine terminations, 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 or that expired.

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Weighted average price of options that were either forfeited or expired.

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

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No definition available.

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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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- Definition

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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No definition available.

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

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No definition available.

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Period from grant date that an equity-based award expires, 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 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		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Shares
Outstanding, beginning of period (in shares)			433,389
Granted (in shares)			454,320
Cancelled or forfeited (in shares)			(44,526)
Outstanding, end of period (in shares)	843,183		843,183		433,389
Vested and Exercisable (in shares)	265,475		265,475
Weighted-Average Exercise Price
Outstanding, beginning of period (in dollars per share)			$ 29.05
Granted (in dollars per share)			4.86
Cancelled or forfeited (in dollars per share)			32.27
Outstanding at end of year (in dollars per share)	$ 15.85		15.85		$ 29.05
Vested and Exercisable (in dollars per share)	$ 35.74		$ 35.74
Weighted Average Remaining Contractual Term (years)
Outstanding			8 years 5 months 5 days		7 years 11 months 19 days
Vested and Exercisable			6 years 8 months 16 days
Aggregate Intrinsic Value
Outstanding	$ 352		$ 352
Vested and Exercisable	$ 4		$ 4
Stock options
Stock Incentive Plans
Vesting period			4 years
Cliff period for vesting			1 year
Exercisable period			10 years
Stock Incentive Plans
Exercised (in shares)	0	0	0
Intrinsic value of options exercised				$ 1
Aggregate fair value of options vested	$ 500	$ 300	$ 1,300	$ 1,400
Weighted average grant date fair value of options granted (in dollars per share)	$ 4.10	$ 4.64	$ 3.25	$ 6.64
Unrecognized compensation expense related to unvested stock option awards	$ 2,300		$ 2,300
Weighted-average amortization period over which cost is expected to be recognized			2 years 3 months 18 days