Summary of significant accounting policies - Goodwill (Details) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
|
Dec. 31, 2016
USD ($)
item
segment
|
Dec. 31, 2015
USD ($)
|
Dec. 31, 2014
USD ($)
|
|
| Summary of significant accounting policies | |||
| Number of reporting units | item | 1 | ||
| Number of operating segments | 1 | ||
| Number of reportable segments | 1 | ||
| Impairment loss | $ | $ 0 | $ 0 | $ 0 |
| X | ||||||||||
- References No definition available.
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| X | ||||||||||
- Definition Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues. No definition available.
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| X | ||||||||||
- Definition Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements. No definition available.
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| X | ||||||||||
- Definition Number of reporting units tested for impairment of goodwill. A reporting unit is an operating segment or one level below an operating segment. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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