XML 158 R75.htm IDEA: XBRL DOCUMENT v3.20.1
Accounts receivable, net - Schedule of Allowance for Doubtful Accounts (Details) - USD ($)
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Accounts receivable, net      
Balance at beginning of the year $ 7,709,000 $ 31,000 $ 119,000
Additions 19,000 7,680,000 27,000
Write-off     (122,000)
Exchange difference (124,000) (2,000) 7,000
Balance at end of the year $ 7,604,000 $ 7,709,000 $ 31,000