Revenue - Deferred revenue (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2019 |
Sep. 30, 2018 |
Sep. 30, 2019 |
Sep. 30, 2018 |
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| Change in contract with customer, liability | ||||
| Amounts invoiced in the period | $ (3,217) | |||
| Revenue in the period | $ (237) | $ (40,792) | (394) | $ (58,026) |
| Foreign exchange arising on consolidation | (140) | |||
| Deferred revenue at end of the period | $ 2,683 | $ 2,683 | ||
| X | ||||||||||
- Definition Amount of increase (decrease) in revenue recognized for cumulative catch-up adjustment from amounts invoiced in the period No definition available.
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| X | ||||||||||
- Definition Amount of increase (decrease) in revenue recognized for cumulative catch-up adjustment from foreign exchange on consolidation. No definition available.
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| X | ||||||||||
- References No definition available.
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| X | ||||||||||
- Definition Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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