Income tax - Changes in the unrecognized tax benefits (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income tax
Unrecognized tax benefits as of January 1,	$ (1,725)	$ (2,626)	$ (398)
Increase related to prior year tax positions	0	0	(2,228)
Decrease related to prior year tax positions	0	434	0
Increase related to current year tax positions	(558)	(418)	0
Settlements	0	885	0
Unrecognized tax benefits as of December 31,	$ (2,283)	$ (1,725)	$ (2,626)

No definition available.

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Amount of increase (decrease) to previously recorded tax expense. Includes, but is not limited to, significant settlements of income tax disputes, and unusual tax positions or infrequent actions taken by the entity, including tax assessment reversal, and IRS tax settlement.

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Amount of unrecognized tax benefits.

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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