Stockholders' Equity - Common Stock (Details)	12 Months Ended
Dec. 31, 2018 Vote $ / shares shares	Dec. 31, 2017 $ / shares shares
Common Stock
Common stock, authorized (in shares)	150,000,000	150,000,000
Par value of common stock (in dollars per share) \| $ / shares	$ 0.001	$ 0.001
Common stock, issued (in shares)	7,141,996	2,364,526
Common Stock, outstanding (in shares)	7,141,996	2,364,526
Number of votes entitled to each common stock share \| Vote	1
Common stock dividends, declared or paid (in dollars per share) \| $ / shares	$ 0
Shares reserved for future issuance (in shares)	5,589,766	421,835
Common stock warrants
Common Stock
Shares reserved for future issuance (in shares)	4,202,449	2,454
Common stock options outstanding
Common Stock
Shares reserved for future issuance (in shares)	433,389	283,277
Common stock options reserved
Common Stock
Shares reserved for future issuance (in shares)	877,917	83,739
Employee Stock Purchase Plan
Common Stock
Shares reserved for future issuance (in shares)	76,011	52,365

Represents common Stock voting rights number of votes per each share.

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- Definition

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.

+ References

No definition available.

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Aggregate number of common shares reserved for future issuance.

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Aggregate dividends declared during the period for each share of common stock outstanding.

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Face amount or stated value per share of common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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