Additional number of common shares reserved for future issuance.

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The maximum value of award or purchase a plan participant can receive under the plan per period.

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The floor for the equity price in relation to the fair market value of common stock on the date of grant or offering, represented as a percentage.

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No definition available.

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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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Aggregate number of common shares reserved for future issuance.

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- Definition

Minimum period the individual is required to perform services to be fully vested under the deferred compensation arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The cash inflow associated with the amount received from the stock plan during the period.

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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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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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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 highest percentage of annual salary that an employee is permitted to utilize with respect to the plan.

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The highest quantity of shares an employee can purchase under the plan per period.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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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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- Definition

Maximum number of shares that may be issued in accordance with the plan as a proportion of outstanding capital stock.

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No definition available.

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- Definition

Number of options vested.

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No definition available.

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Number of shares issued during the period as a result of an employee stock purchase plan.

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Stock-Based Compensation (Details) - USD ($)			1 Months Ended		3 Months Ended		6 Months Ended
Stock-Based Compensation (Details) - USD ($)	Jun. 30, 2019	Apr. 30, 2019	Dec. 31, 2018	Jun. 30, 2017	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jan. 31, 2019	Jun. 30, 2015
Chief Executive Officer
Stock Based Compensation
Stock option shares approved				425,000
2015 Plan
Stock Based Compensation
Shares reserved for issuance										3,451,495
Additional shares reserved for issuance										9,890,310
Employee stock purchase plan
Stock Based Compensation
Issuance of common stock under employee stock purchase plan (in shares)	0	132,177
Proceeds from issuance of common stock under employee stock purchase plan		$ 2,100,000
Performance-based awards
Stock Based Compensation
Stock option shares approved			600,000
Stock-based compensation expense			$ 0
Performance-based awards \| Chief Executive Officer
Stock Based Compensation
Stock option shares approved				200,000					200,000
Requisite service period				3 years
Stock-based compensation expense					$ 200,000	$ 100,000	$ 200,000	$ 300,000
Performance-based awards \| First Vesting Milestone \| Chief Executive Officer
Stock Based Compensation
Number of options vested				50,000
Vesting period				1 year
Performance-based awards \| Second Vesting Milestone \| Chief Executive Officer
Stock Based Compensation
Number of options vested				75,000
Vesting period				1 year
Performance-based awards \| Third Vesting Milestone \| Chief Executive Officer
Stock Based Compensation
Number of options vested				75,000
Vesting period				1 year
Employee and non-employee stock options
Stock Based Compensation
Stock-based compensation expense					$ 5,804,000	$ 3,368,000	$ 9,855,000	$ 6,522,000
Shares available for issuance	6,503,000		5,431,000		6,503,000		6,503,000
Restricted stock units
Stock Based Compensation
Shares granted							1,625,000
Restricted stock units \| Chief Executive Officer
Stock Based Compensation
Stock option shares approved									100,000
Stock-based compensation expense					$ 200,000		$ 200,000
Restricted stock units \| Chief Financial Officer and Chief Operating Officer
Stock Based Compensation
Stock-based compensation expense					$ 400,000		$ 400,000
2015 Employee Stock Purchase Plan
Stock Based Compensation
Shares reserved for issuance	893,548				893,548		893,548
Shares reserved for issuance as a proportion common stock outstanding (as a percent)							1.00%
Price in relation to fair market value of common stock on the date of grant, lower range limit (as a percent)							85.00%
Maximum number of shares a participant may receive during the period (in shares)							5,000
Maximum amount of award or purchase during a calendar year							$ 25,000
Maximum employee contribution of employee's cash compensation (as a percent)	15.00%				15.00%		15.00%
2015 Employee Stock Purchase Plan \| Minimum
Stock Based Compensation
Shares reserved for issuance	880,000				880,000		880,000