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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Gross number of share options (or share units) granted during the period.

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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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Per share or per unit amount of equity securities issued.

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No definition available.

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Number of new stock issued during the period.

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Note 5 - Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended
	Feb. 28, 2021	Jan. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Stock Issued During Period, Shares, New Issues (in shares)			0
Proceeds from Issuance of Common Stock			$ 0	$ 74,685
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)			21,667
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price (in dollars per share)			$ 1.61
Share-Based Payment Arrangement, Option [Member] \| Minimum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)			3 years
Share-Based Payment Arrangement, Option [Member] \| Maximum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)			4 years
The 2015 Stock Plan [Member]
Common Stock, Capital Shares Reserved for Future Issuance (in shares)			19,961
Underwritten Public Offering [Member]
Stock Issued During Period, Shares, New Issues (in shares)	14,273,684
Shares Issued, Price Per Share (in dollars per share)	$ 4.75
Proceeds from Issuance of Common Stock	$ 78,000
Over-Allotment Option [Member]
Stock Issued During Period, Shares, New Issues (in shares)	2,141,052
The 2020 ATM Agreement [Member]
Stock Issued During Period, Shares, New Issues (in shares)		468,684
Proceeds from Issuance of Common Stock		$ 2,900