Revenue from contracts with customers - Receivables, Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Contract assets:
Trade account receivable	$ 542	$ 757
Unbilled receivables, included in 'Prepaid expenses and other current assets'	59	58
Total contract assets	601	815
Contract liabilities:
Deferred revenue, current	1,827	1,781
Deferred revenue, noncurrent	9	9
Customer deposit, included in 'Accrued expenses and other current liabilities'	45	45
Total contract liabilities	$ 1,881	$ 1,835