Significant accounting policies - Goodwill and intangible assets (Details) - Software	12 Months Ended
Dec. 31, 2019
Minimum
Disclosure of detailed information about intangible assets [line items]
Estimated useful life	3 years
Maximum
Disclosure of detailed information about intangible assets [line items]
Estimated useful life	5 years

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

No definition available.

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration