Summary of significant accounting policies (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2025 USD ($) segment	Dec. 31, 2024 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Summary of Significant Accounting Policies [Line Items]
Number of operating segments | segment	1
Number of reportable segments | segment	1
Unrealized gain (loss) on fair value adjustment for warrants	$ (4)
Warrants, fair value	$ 99	$ 103	$ 77	$ 77
Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Operating leases, initial terms	36 months
Operating leases, period for non-accrual status	90 days
Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Required assets value of financial institutions for cash deposits	$ 10,000,000
Operating leases, initial terms	120 months
Operating leases, period of review for impairment	90 days