v3.21.2

Summary of significant accounting policies (Additional Information) (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019
Restricted cash |  |
Restricted Cash | $ 0 | $ 0
Accounts receivable, net |  |
Allowance for Doubtful Accounts Receivable, Current | 2,174 | 196
Other receivables and Prepayments |  |
Allowance for uncollectible other receivables and prepayments | $ 39 | 0
Foreign currency translation |  |
Term of single performance obligation satisfied over time | 10 years |
Unbilled Contracts Receivable | $ 0 | $ 0
Minimum [Member] |  |
Foreign currency translation |  |
Actual electricity running cost (as a percent) | 0.00% |
Rebate (as a percent) | 2.00% |
Maximum [Member] |  |
Foreign currency translation |  |
Actual electricity running cost (as a percent) | 40.00% |
Rebate (as a percent) | 20.00% |
Maximum [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-12-31 |  |
Foreign currency translation |  |
Term of contract | 10 years |

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