Taxes - Summary of income tax reconciliation (Details) - EUR (€) € in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Taxes
Income / loss (-) before tax	€ (115,507)	€ 54,246	€ (119,627)
Income tax debit / credit (-), calculated using the Belgian statutory tax rate on the accounting income / loss (-) before tax (theoretical)	(39,261)	18,438	(40,661)
Tax expenses / income (-) in income statement (effective)	198	235	(1,218)
Difference in tax expense / income to explain	39,458	(18,203)	39,444
Effect of tax rates in other jurisdictions	14	163	328
Effect of non-taxable revenues	(11,277)	(27,399)	(5,934)
Effect of consolidation entry without tax impact	5,419	3,533	1,652
Effect of non-tax deductible expenses	404	856	10,783
Effect of recognition of previously non recognized deferred tax assets	(414)	(421)	(1,307)
Effect of change in tax rates	181
Effect of tax losses (utilized) reversed	(763)	(655)	(597)
Effect from under or over provisions in prior periods			58
Effect of non-recognition of deferred tax assets	45,895	5,720	34,783
Effect of R&D tax credit claims			(322)
Total explanations	€ 39,458	€ (18,203)	€ 39,444

Represents the amount explained of the difference in tax expense (income) between the statutory and effective tax rate.

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- Definition

Represents the difference in tax expense (income) between statutory and effective tax rate.

+ References

No definition available.

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The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to non recognition of deferred tax assets in determining taxable profit (tax loss). [Refer: Accounting profit]

+ References

No definition available.

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The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to Research and Development tax credit claims in determining taxable profit (tax loss). [Refer: Accounting profit]

+ References

No definition available.

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- Definition

The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to tax losses (utilized) reversed in determining taxable profit (tax loss). [Refer: Accounting profit]

+ References

No definition available.

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The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to under or over provisions from prior periods in determining taxable profit (tax loss). [Refer: Accounting profit]

+ References

No definition available.

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- Definition

The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to the effect of consolidation entry without tax impact in determining taxable profit (tax loss). [Refer: Accounting profit]

+ References

No definition available.

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- Definition

The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to recognition of previously non recognized deferred tax assets in determining taxable profit (tax loss). [Refer: Accounting profit]

+ References

No definition available.

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- Definition

The amount of profit (loss) for a period before deducting tax expense. [Refer: Profit (loss)]

+ References

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- Definition

The aggregate amount included in the determination of profit (loss) for the period in respect of current tax and deferred tax that relate to continuing operations. [Refer: Continuing operations [member]; Current tax expense (income); Deferred tax expense (income)]

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- Definition

The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to changes in the tax rate. [Refer: Accounting profit]

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- Definition

The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to expenses not deductible in determining taxable profit (tax loss). [Refer: Accounting profit]

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The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to foreign tax rates. [Refer: Accounting profit]

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The amount that represents the difference between the tax expense (income) and the product of the accounting profit multiplied by the applicable tax rate(s) that relates to revenues that are exempt from taxation. [Refer: Accounting profit]

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The product of the accounting profit multiplied by the applicable tax rate(s). [Refer: Accounting profit; Applicable tax rate]

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