Refers to the number of years shares will automatically increase.

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Refers to the percentage of annual increase which is equal to the company's fully diluted share.

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Unrecognized cost of unvested share-based compensation awards.

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

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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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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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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest options outstanding. 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 options outstanding that can 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 options outstanding. 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 option holders acquired shares when converting their stock options into shares.

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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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Weighted average remaining contractual term for fully vested and expected to vest options outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents 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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Number of options vested.

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Weighted average grant-date fair value of options vested.

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No definition available.

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

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Share-Based Compensation - Stock Options (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2019	Sep. 30, 2016	Apr. 30, 2016	Apr. 30, 2015
Stock Options, Additional Disclosures
Vested	87,021	127,062	166,133	307,410
Percentage of company's fully diluted shares	20.00%		20.00%
Unrecognized share-based compensation cost					$ 3,900,000
Unrecognized share-based compensation - Weighted average period					1 year 6 months
2015 Plan
Stock Options, Additional Disclosures
Vested					709,521	861,645	276,248
A&R 2015 Plan
Stock Options, Additional Disclosures
Common stock reserved for issuance (in shares)	1,030,583		1,030,583		415,077	0			501,001
Outstanding, Number, Ending Balance (in shares)	2,722,973		2,722,973
Vested			1,930,014
Number of years common shares automatically increase			10 years		10 years
Percentage of company's fully diluted shares					20.00%
Unrecognized share-based compensation cost	$ 2,800,000		$ 2,800,000
Unrecognized share-based compensation - Weighted average period			1 year 1 month 6 days
Inducement Plan
Stock Options, Additional Disclosures
Common stock reserved for issuance (in shares)	249,479		249,479							300,000
Employees, Directors And Consultants \| 2015 Plan
Stock Options, Additional Disclosures
Common stock reserved for issuance (in shares)												320,615
Employees, Directors And Consultants \| A&R 2015 Plan
Stock Options, Additional Disclosures
Common stock reserved for issuance (in shares)											2,400,000
Employees, Directors And Consultants \| Inducement Plan
Stock Options, Additional Disclosures
Vesting period					4 years
Officers, Directors, And Employees \| A&R 2015 Plan
Stock Options, Additional Disclosures
Granted (in shares)					772,000	150,500	1,825,700
Officers And Employees \| Inducement Plan
Stock Options, Additional Disclosures
Granted (in shares)					50,000	98,000	198,000
Minimum \| Employees, Directors And Consultants \| A&R 2015 Plan
Stock Options, Additional Disclosures
Vesting period					3 years
Maximum \| Employees, Directors And Consultants \| A&R 2015 Plan
Stock Options, Additional Disclosures
Vesting period					4 years
Stock options
Stock Options, Additional Disclosures
Outstanding, Number, Beginning Balance (in shares)			2,800,774	2,464,140	2,464,140	2,242,800	302,842
Granted (in shares)					822,000	248,500	2,023,700
Exercised (in shares)					(40,398)	(23,910)
Forfeited/Cancelled (in shares)					(444,968)	(3,250)	(83,742)
Outstanding, Number, Ending Balance (in shares)					2,800,774	2,464,140	2,242,800	302,842
Vested and exercisable (in shares)					1,812,181
Vested and expected to vest (in shares)					2,800,774
Outstanding, Weighted Average Exercise Price, Beginning Balance (in dollars per share)			$ 9.02	$ 9.46	$ 9.46	$ 9.07	$ 2.43
Granted (in dollars per share)					8.24	12.24	10.07
Exercise price (in dollars per share)					2.25	1.92
Forfeited/Cancelled (in dollars per share)					10.61	1.34	9.12
Outstanding, Weighted Average Exercise Price, Ending Balance (in dollars per share)					9.02	$ 9.46	$ 9.07	$ 2.43
Vested and exercisable (in dollars per share)					9.15
Vested and expected to vest (in dollars per share)					$ 9.02
Options, Outstanding, Weighted Average Remaining Contractual Term (years)					7 years 11 months 16 days	8 years 6 months 29 days	9 years 5 months 23 days	9 years 7 months 6 days
Vested and exercisable (years)					7 years 8 months 19 days
Vested and expected to vest (years)					7 years 11 months 16 days
Options, Outstanding, Aggregate Intrinsic Value					$ (22,994,287)	$ (3,715,000)	$ (2,759,000)	$ 1,031,000
Vested and exercisable					(15,120,294)
Vested and expected to vest					$ (22,994,287)
Common stock aggregate intrinsic value of exercise price					$ 0.81	$ 7.95	$ 7.84
Weighted average fair value per share of options granted					5.07	7.35	6.37
Weighted average fair value per share of options vested					$ 6.15	$ 5.99	$ 4.59
Forfeited					444,968	3,250	83,742
Forecast \| A&R 2015 Plan
Stock Options, Additional Disclosures
Common stock reserved for issuance (in shares)									501,001