Income taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Current:
Federal	$ 453	$ (428)
State and local	350	80
Current Income Tax Expense (Benefit), Total	803	(348)
Deferred
Federal	267	80
State and local	70	83
Deferred Income Tax Expense (Benefit), Total	337	163
Expense (benefit) for income taxes	$ 1,140	$ (185)