Nature of business and summary of significant accounting policies - Deferred financing costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Deferred financing costs	$ 0	$ 0	$ 207
Amortization of debt issuance costs and discounts	336	336	358
Accumulated amortization	1,056	720	616
Write-offs of debt unamortized costs	$ 0	$ 0	$ 0