Represents the increase in number of shares available for grant during the period.

No definition available.

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The number of vested and unvested awards modified under an equity-based compensation plan.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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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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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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

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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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An excess of the fair value of the modified award over the fair value of the award immediately before the modification.

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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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Value of stock (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of stock value of such awards forfeited. Stock issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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Stock-Based Compensation - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended
	Jan. 31, 2019	Feb. 28, 2018	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Jan. 31, 2018
Share-based Compensation
Total grant date fair value of options vested			$ 710,000	$ 377,000
Shares available for future issuance (in shares)			867,509		764,145
Value of share issued			$ 13,000	309,000
Weighted-average exercise price (per share)			$ 7.28		$ 7.60
Number of stock options granted (in shares)			417,000
Options remained outstanding			1,796,103		1,475,299
Stock-based compensation expense			$ 704,000	$ 625,000
Immediate vesting
Share-based Compensation
Incremental modification value		$ 63,000
Remaining vesting
Share-based Compensation
Incremental modification value		$ 537,000
Chief Executive Officer
Share-based Compensation
Number of vested and unvested stock option award modified		400,000
Weighted-average exercise price (per share)		$ 7.64				$ 16.25
Incremental modification value		$ 600,000
Employees [Member]
Share-based Compensation
Weighted-average grant date fair value of options granted			$ 4.00	$ 4.74
2016 Employee Stock Purchase Plan
Share-based Compensation
Increase in number of shares available for grant	170,955
Shares available for future issuance (in shares)			440,344
Value of share issued			$ 0	$ 0