Name:	glpg_CorporateIncomeTaxesAbstract
Namespace Prefix:	glpg_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The excess of threshold notional income deduction, as a deduction of second basket percentage.

No definition available.

Name:	glpg_ExcessOfThresholdNotionalIncomeDeductionAsDeductionOfSecondBasketPercentage
Namespace Prefix:	glpg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Innovation Income Deduction Carryforward

No definition available.

Name:	glpg_InnovationIncomeDeductionCarryforward
Namespace Prefix:	glpg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The percentage of innovation time deduction tax rate.

No definition available.

Name:	glpg_InnovationTimeDeductionTaxRate
Namespace Prefix:	glpg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The amount stands for statutory tax losses that can be compensable with future statutory taxable profits for a limited period.

No definition available.

Name:	glpg_NonCompensableStatutoryTaxLosses
Namespace Prefix:	glpg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The notional income deduction carry forward limitation period, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	glpg_NotionalIncomeDeductionCarryForwardLimitationPeriod
Namespace Prefix:	glpg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The element stands for number of subsidiaries having sufficient profits against them unused tax losses can be utilized.

No definition available.

Name:	glpg_NumberOfSubsidiariesHavingSufficientProfits
Namespace Prefix:	glpg_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Taxable base after application of the first basket

No definition available.