Prepaid expenses and other current assets, net (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Value-added tax recoverable, current	$ 0	$ 268
Deposit and prepayment for acquisitions, net of provision of $9,916 and $11,069, respectively	52	56
Provision for deposit and prepayment for acquisitions	9,916	11,069
Other deposit and prepayment, net of provision of $648 and $841, respectively (a)	7,674	2,891
Provision for other deposits and prepayments	648	841
Other receivable, net of provision of $2,306 and $2,466, respectively (b)	1,858	1,803
Provision for other receivables	2,306	2,466
Total prepaid expenses and other current assets, net	$ 9,584	$ 5,018