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

The increase (decrease) in profit and loss as a result of an decrease in a designated risk component that was reasonably possible at the end of the reporting period. Excludes defined benefit plan obligations.

No definition available.

Name:	glpg_IncreaseDecreaseInProfitAndLossDueToReasonablyPossibleDecreaseInDesignatedRiskComponent
Namespace Prefix:	glpg_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

The increase (decrease) in profit and loss as a result of an increase in a designated risk component that was reasonably possible at the end of the reporting period. Excludes defined benefit plan obligations.

No definition available.

Name:	glpg_IncreaseDecreaseInProfitAndLossDueToReasonablyPossibleIncreaseInDesignatedRiskComponent
Namespace Prefix:	glpg_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

The reasonably possible percentage of change in the designated risk component used to determine the value of the financial instrument. Excludes defined benefit plan obligations.

No definition available.

Name:	glpg_PercentageOfReasonablyPossibleChangeInRiskAssumption
Namespace Prefix:	glpg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The reasonably possible percentage of the decrease in the designated risk component used to determine the value of the financial instrument. Excludes defined benefit plan obligations.

No definition available.

Name:	glpg_PercentageOfReasonablyPossibleDecreaseInRiskAssumption
Namespace Prefix:	glpg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The reasonably possible percentage of the increase in the designated risk component used to determine the value of the financial instrument. Excludes defined benefit plan obligations

No definition available.

Name:	glpg_PercentageOfReasonablyPossibleIncreaseInRiskAssumption
Namespace Prefix:	glpg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The amount of current finance lease liabilities. [Refer: Finance lease liabilities]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Note Expiry date 2019-01-01
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 55
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-02&anchor=para_55&doctype=Standard&book=B
-URIDate 2017-03-09

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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.

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

Name:	ifrs-full_TypesOfRisksAxis=ifrs-full_InterestRateRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ifrs-full_TypesOfRisksAxis=ifrs-full_CurrencyRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CurrencyAxis=glpg_EuroUsdExchangeRateValueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CurrencyAxis=glpg_EuroGbpExchangeRateValueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CurrencyAxis=glpg_EuroChFrancsExchangeRateValueMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_CurrencyAxis=glpg_EuroHrKunasExchangeRateValueMember
Namespace Prefix:
Data Type:	na
Balance Type:
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