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Significant accounting policies - Intangible assets (Details) | 12 Months Ended
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Dec. 31, 2018
Internal-use software |
Finite-Lived Intangible Assets [Line Items] |
Intangible assets, useful life | 4 years
Customer contracts | Minimum |
Finite-Lived Intangible Assets [Line Items] |
Intangible assets, useful life | 1 year
Customer contracts | Maximum |
Finite-Lived Intangible Assets [Line Items] |
Intangible assets, useful life | 2 years
Favourable land lease |
Finite-Lived Intangible Assets [Line Items] |
Intangible assets, useful life | 27 years
Assembled workforce |
Finite-Lived Intangible Assets [Line Items] |
Intangible assets, useful life | 5 years
Partnership relationship |
Finite-Lived Intangible Assets [Line Items] |
Intangible assets, useful life | 5 years
Brand |
Finite-Lived Intangible Assets [Line Items] |
Intangible assets, useful life | 5 years

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- Definition Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Details
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- Details
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- Details
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