Government assistance programs (Details) - USD ($)	1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	Jan. 31, 2023	Jul. 31, 2020	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022	May 31, 2021	Mar. 27, 2020
Unusual or Infrequent Item, or Both [Line Items]
Contra-research and development expense				$ 600,000		$ 600,000
Refundable employee retention credit									$ 800,000
Contra General And Administrative Expense				200,000		200,000
Contra expenses			$ 0		$ 0
Employee retention credit receivable			$ 208,000		$ 208,000		$ 847,000
Other Transaction Authority for Prototype Agreement
Unusual or Infrequent Item, or Both [Line Items]
Grants Receivable		$ 13,300,000						$ 17,600,000
Expenses relating to extension of an agreement	$ 0
Payment period of reimbursement contract		30 days
Contra-research and development expense				$ 11,000		$ 600,000
Reimbursement expenses received							$ 17,600,000