| Accounts receivable, net |
| | December 31, 2020 | | | December 31, 2019 | | Accounts receivable | | $ | 69,694 | | | $ | 68,309 | | | Less: Allowance for credit losses | | | (15,366) | | | | (16,377) | | | Accounts receivable, net | | $ | 54,328 | | | $ | 51,932 | | | | | | | | | | | | | |
|
| Allowance for doubtfull receivables |
Allowance for credit losses | | Balance at Beginning of Period | | | | Charges to Costs and Expenses | | | Amount Utilized | | | Balance at End of Period | | Year ended December 31, 2018 | | $ | (19,706 | ) | | | $ | (575 | ) | | $ | 4,195 | | | $ | (16,086 | ) | Year ended December 31, 2019 | | $ | (16,086 | ) | | | $ | (999 | ) | | $ | 708 | | | $ | (16,377 | ) | Year ended December 31, 2020 | | $ | (16,377 | ) | | | $ | (541 | ) | | $ | 1,552 | | | $ | (15,366 | ) |
|