DoD expense reimbursement contract (Details) - Other Transaction Authority for Prototype Agreement - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jul. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	May 31, 2021
Unusual or Infrequent Item, or Both [Line Items]
Grants Receivable	$ 13.3			$ 17.6
Payment period of reimbursement contract	30 days
Contra-research and development expense		$ 15.2	$ 1.7
Prepaid expenses and other current assets		2.7	0.9
Deferred research obligation liability		2.0	0.0
Grant expected to be received		1.6	$ 0.0
Grants receivable current		$ 0.2