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- Definition

Common Stock, Shares Outstanding, Agreement Threshold, Percent

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- Definition

Common Stock, Shares Outstanding of Affiliate Beneficial Ownership, Agreement Threshold, Percent

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- Definition

Number of warrants or rights outstanding.

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- Definition

Face amount or stated value per share of common stock.

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- Definition

Amount of increase (decrease) of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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- Definition

The minimum amount the entity agreed to spend under the long-term purchase commitment.

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Period covered by the long-term purchase commitment, 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 from the additional capital contribution to the entity.

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- Definition

Cash received on stock transaction after deduction of issuance costs.

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No definition available.

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- Definition

The number of shares issued or sold by the subsidiary or equity method investee per stock transaction.

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No definition available.

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Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.

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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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- Definition

Price of a single share of a number of saleable stocks of a company.

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No definition available.

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- Definition

Number of new stock issued during the period.

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- Definition

Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

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Stockholders' equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended				3 Months Ended		49 Months Ended
	Jun. 21, 2019	Jan. 31, 2020	Oct. 31, 2019	Feb. 28, 2019	Jan. 31, 2018	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2019	Dec. 31, 2019	Jan. 01, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock						$ 440	$ 14,026
Proceeds from issuance of common stock						$ 440	$ 0
Pre-Funded Warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants to purchase common stock (in shares)						531,250
Private Placement Warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants to purchase common stock (in shares)						932,812
Preferred Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock (in shares)							0
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock						$ 1	$ 3
Issuance of common stock (in shares)						187,000	3,200,000
Common Stock \| At-the-market equity offering program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock (in shares)								500,000
Proceeds from issuance of common stock								$ 4,000
2019 Public Offering \| Common Stock \| Concurrent Offerings
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock (in shares)	10,500,000
2019 Public Offering \| Common Stock \| Over-Allotment Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of stock, consideration received on transaction	$ 5,500
Warrants to purchase common stock (in shares)	1,575,000
Proceeds from issuance of common stock	$ 38,400
2019 Public Offering \| Common Class A
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share price (in dollars per share)	$ 3.5
Sale of stock, consideration received on transaction	$ 36,800
2018 Public Offering \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Par value (in dollars per share)					$ 0.001
Number of shares issued in transaction (in shares)					6,670,625
Equity Rights Letter Agreement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of stock, price per share (in dollars per share)				$ 4.02
Sale of stock, consideration received on transaction				$ 13,800
Equity Rights Letter Agreement \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued in transaction (in shares)				3,199,998
Private Placement - Second Closing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of stock, consideration received on transaction				$ 24,200
Warrants \| (Level 3)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of Warrants						$ 1,705			$ 2,486	$ 18,200
Change in fair value						$ (781)
Lincoln Park Capital \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock		$ 400	$ 2,500
Share price (in dollars per share)			$ 2.587
Purchase agreement period (in months)			30 months
Purchase commitment amount			$ 27,500
Shares issued as commitment fee			289,966
Issuance of common stock (in shares)		186,986
Lincoln Park Capital \| Common Stock \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Shares Outstanding of Affiliate Beneficial Ownership, Agreement Threshold, Percent			9.99%
Issuance of common stock (in shares)			5,227,323
Common Stock, Shares Outstanding, Agreement Threshold, Percent			19.99%