Aggregate number of common shares reserved for future issuance.

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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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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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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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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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Exercise price as percentage of fair value of common stock on grant date if optionee owns stock representing more than 10 percent of voting power of all classes of stock.

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Percentage of increase in common stock capital shares reserved for future issuance.

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Percentage of voting power of all classes of stock to be owned by optionee to determine exercise price.

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Stock-Based Compensation - Additional Information (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total shares of common stock reserved	3,350,046		3,350,046
Weighted-average grant date fair value of stock options granted to employees	$ 2.65	$ 15.63
Options granted	135,972
Aggregate grant date fair value of stock options vested	$ 53,716	$ 79,000
Total unrecognized compensation cost related to stock options granted to employees	$ 710,285		$ 435,639
2018 Omnibus Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total shares of common stock reserved	425,000
Percentage of total shares of common stock reserved	2.00%
2018 Omnibus Incentive Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of voting power of all classes of stock to be owned by optionee to determine the exercise price	10.00%
Exercise price as a percentage of fair value of common stock on grant date if optionee owns stock representing more than 10 percent of voting power of all classes of stock	110.00%
Employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized compensation cost related to stock options granted to employees, weighted-average recognition period	3 years 3 months 19 days		2 years 9 months 18 days
Employee Stock Options \| 2011 Employee Equity Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted, expiration year	5 years
Employee Stock Options \| 2011 Employee Equity Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted, expiration year	10 years
Employee Stock Options \| 2018 Omnibus Incentive Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted, expiration year	5 years
Employee Stock Options \| 2018 Omnibus Incentive Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted, expiration year	10 years