Deferred income tax - Consolidated statement of financial position (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred income tax
Deferred income tax asset, net	$ 74,556	$ 38,305
Deferred income tax liability, net	28,959	31,422
Deferred tax liability (asset)	$ 45,597	$ 6,883	$ 27,339

The amounts of income taxes recoverable in future periods in respect of: (a) deductible temporary differences; (b) the carryforward of unused tax losses; and (c) the carryforward of unused tax credits. [Refer: Temporary differences [member]; Unused tax credits [member]; Unused tax losses [member]]

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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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