Leases - Schedule of Right-of-Use Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Lessee, Lease, Description [Line Items]
Less accumulated amortization	$ (492)	$ (905)
Right-of-use asset, net	335	527
Palo Alto, CA Office
Lessee, Lease, Description [Line Items]
Right-of-use asset, before accumulated amortization	0	630
Berlin, Germany Office
Lessee, Lease, Description [Line Items]
Right-of-use asset, before accumulated amortization	523	508
Frankfurt, Germany Office
Lessee, Lease, Description [Line Items]
Right-of-use asset, before accumulated amortization	$ 304	$ 294