Share-Based Compensation - Stock option and restricted stock unit activity (Details) - Biostage2013 Equity Incentive Plan [Member] - Stock Options [Member] shares in Thousands	3 Months Ended
Mar. 31, 2021 $ / shares shares
Amount, Outstanding \| shares	1,599,720
Amount, Granted \| shares	16,413
Amount, Outstanding \| shares	1,616,134
Weighted-average exercise price, Outstanding \| $ / shares	$ 6.33
Weighted-average exercise price, Granted \| $ / shares	1.80
Weighted-average exercise price, Outstanding \| $ / shares	$ 6.31

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

No definition available.

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- Definition

Number of options outstanding, including both vested and non-vested options.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

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- Definition

Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

+ References

No definition available.

+ Details

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- Details

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- Details

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