Balance Sheet Information - Accrued expenses and other payables (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Balance Sheet Information
Accrued selling, general and administrative expenses	$ 2,692	$ 2,720
Accrued salary and bonus	398	2,005
Accrued employee benefits	852	564
Accrued cost of service	970	627
Accrued taxes (including VAT)	3,290	2,637
Accrued interest payable	142	53
Accrued customer credit	2,018	3,393
Other accrued expenses	2,330	1,617
Accrued expenses and other payables	$ 12,692	$ 13,616