Leases - Costs (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Leases
Total lease costs	$ 0.6	$ 0.6
Impairment losses of ROU assets	$ 0.0	0.0
Clinical site equipment
Leases
Weighted-average incremental borrowing rate used to determine right-of-use assets and lease liabilities	7.00%
Real estate
Leases
Weighted-average incremental borrowing rate used to determine right-of-use assets and lease liabilities	11.00%
Maximum
Leases
Short-term operating lease costs	$ 0.1	$ 0.1

Amount of lease cost recognized by lessee for lease contract.

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Discount rate used by lessee to determine present value of operating lease payments.

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Amount of loss from impairment of right-of-use asset from operating lease.

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Amount of short-term lease cost, excluding expense for lease with term of one month or less.

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