Income/loss (-) per share (Details) - EUR (€) € / shares in Units, € in Thousands, shares in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income/loss (-) per share: Basic
Net income/loss (-) attributable to owners of the parent (Euro, in thousands)	€ 149,845	€ (29,259)	€ (115,704)
Weighted average number of shares for the purpose of income/loss (-) per share	57,614	52,113	49,479
Basic income/loss (-) per share	€ 2.60	€ (0.56)	€ (2.34)
Income/loss per share: Diluted
Net income/loss (-) attributable to owners of the parent (Euro, in thousands)	€ 149,845	€ (29,259)	€ (115,704)
Weighted average number of shares for the purpose of income/loss (-) per share	57,614	52,113	49,479
Number of dilutive potential ordinary shares	2,498
Diluted income/loss (-) per share	€ 2.49	€ (0.56)	€ (2.34)

The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator) divided by the weighted average number of ordinary shares outstanding during the period (the denominator).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator), divided by the weighted average number of ordinary shares outstanding during the period (the denominator), both adjusted for the effects of all dilutive potential ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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- Definition

The number of dilutive potential ordinary shares that relate to the assumed exercise of the entity's share options.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition

The profit (loss) attributable to ordinary equity holders of the parent entity. [Refer: Profit (loss)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

The number of ordinary shares outstanding at the beginning of the period, adjusted by the number of ordinary shares bought back or issued during the period multiplied by a time-weighting factor.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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