Accounts receivables, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for doubtful accounts
Balance at the beginning of the year	$ 1,086	$ 1,183	$ 863
Additions charged to operations	28	181	363
Deductions from reserves, net	(106)	(278)	(43)
Balance at the end of the year	$ 1,008	$ 1,086	$ 1,183