Accounts Receivable

9 Months Ended

12 Months Ended

Sep. 30, 2021

Dec. 31, 2020

Receivables [Abstract]

ACCOUNTS RECEIVABLE

4. ACCOUNTS RECEIVABLE

Accounts receivable consisted of the following:

	December 31, 2020			September 30, 2021
Accounts receivable	$	81,345		$	72,039
Allowance for doubtful accounts		(5,047	)		(4,796	)
Accounts receivable, net	$	76,298		$	67,243

Movement of allowance for doubtful accounts was as follows:

	Three Months Ended September 30,					Nine Months Ended September 30,
	2020		2021			2020			2021
Balance at beginning of the period	$	4,534	$	4,743		$	5,537		$	5,047
Charge to expenses		2		457			(861	)		261
Write off		—		(415	)		—			(546	)
Exchange difference		173		11			33			34
Balance at end of the period	$	4,709	$	4,796		$	4,709		$	4,796

3. ACCOUNTS RECEIVABLE

Accounts receivable consisted of the following:

	December 31, 2019			December 31, 2020
Accounts receivable	$	73,178		$	81,345
Allowance for doubtful accounts		(5,537	)		(5,047	)
Accounts receivable, net	$	67,641		$	76,298

Movement of allowance for doubtful accounts was as follows:

	December 31, 2019			December 31, 2020
Balance at beginning of year	$	10,111		$	5,537
Charge to expenses		(4,250	)		(240	)
Write off		(233	)		(493	)
Exchange difference		(91	)		243
Balance at end of year	$	5,537		$	5,047