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Summary of significant accounting policies - Cash and restricted cash (Details) $ in Thousands | 12 Months Ended |
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Dec. 31, 2023 USD ($) item | Dec. 31, 2022 USD ($) item | Dec. 31, 2021 USD ($)
Accounting Policies [Abstract] |  |  |
Cash investment term | 90 days |  |
Cash classified as restricted | $ | $ 300 | $ 300 | $ 300
Number of standby letters of credit | item | 2 | 2 |

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- Definition Represents the investment term. + References No definition available. + Details
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- Definition Number of standby letters of credit. + References No definition available. + Details
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- References No definition available. + Details
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- Definition Amount of cash restricted as to withdrawal or usage, classified as noncurrent. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(17)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 45 -Paragraph 5 -SubTopic 210 -Topic 954 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480632/954-210-45-5 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482913/230-10-50-8 + Details
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