Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Amount of cost to be recognized for option under share-based payment arrangement.

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Share-based compensation - Costs (Details) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
Share-based compensation - Costs (Details) - USD ($)	Aug. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 0	$ 749,000	$ 39,000	$ 1,074,000	$ 185,000
Unrecognized compensation cost		12,900,000		$ 12,900,000
Recognition period				3 years 7 months 6 days
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		381,000	31,000	$ 552,000	130,000
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 368,000	$ 8,000	$ 522,000	$ 55,000