The strike price on the financial instrument asset

No definition available.

Name:	glpg_FinancialInstrumentStrikePrice
Namespace Prefix:	glpg_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the price per share for equity investment received for a global collaborative agreement.

+ References

No definition available.

+ Details

Name:	glpg_InitialPricePerShareEquityInvestmentReceivedGlobalCollaborationAgreement
Namespace Prefix:	glpg_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The element stands for number of counterparties.

+ References

No definition available.

+ Details

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

- Definition

The element stands for number of valuation date.

+ References

No definition available.

+ Details

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

- Definition

Payment Composed Of License Fee And Equity Investment Global Collaboration Agreement

+ References

No definition available.

+ Details

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

- Definition

The amount of current derivative financial assets. [Refer: Derivative financial assets]

+ References

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

+ Details

Name:	ifrs-full_CurrentDerivativeFinancialAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The decrease in financial assets resulting from derecognition. [Refer: Financial assets]

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Note Effective 2018-01-01
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+ Details

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

- Definition

The amount of liability representing income that has been received but is not yet earned. [Refer: Revenue]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
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-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_78&doctype=Standard
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+ Details

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

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

The amount of assets that are: (a) cash; (b) an equity instrument of another entity; (c) a contractual right: (i) to receive cash or another financial asset from another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially favourable to the entity; or (d) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to receive a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose the entity’s own equity instruments do not include puttable financial instruments classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. [Refer: Financial instruments, class [member]; Financial liabilities]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
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-Paragraph 25
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+ Details

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

- Definition

The fair value of financial assets. [Refer: At fair value [member]; Financial assets]

+ References

+ Details

Name:	ifrs-full_FinancialAssetsAtFairValue
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The gains (losses) on hedging instruments in fair value hedges. [Refer: Fair value hedges [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2018-01-01
-Name IFRS
-Number 7
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-URIDate 2017-03-09

+ Details

Name:	ifrs-full_GainsLossesOnHedgingInstrument
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The gains (losses) recognised in profit or loss for the entity's own equity instruments measured at fair value that are attributable to the change in unrealised gains or losses relating to those instruments held at the end of the reporting period. [Refer: At fair value [member]; Entity's own equity instruments [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 13
-IssueDate 2017-01-01
-Paragraph 93
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-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=13&date=2017-03-01&anchor=para_93_f&doctype=Standard
-URIDate 2017-03-09

+ Details

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

- Definition

The increase in equity through the issue of equity instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 106
-Subparagraph d
-Clause iii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_106_d_iii&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_IssueOfEquity
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	ifrs-full_CounterpartiesAxis=glpg_GileadSciencesIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_MeasurementAxis=ifrs-full_RecurringFairValueMeasurementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
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Period Type:

Fair value re-measurement of share subscription agreement (Details) € / shares in Units, $ in Millions				1 Months Ended		11 Months Ended	12 Months Ended
	Jan. 19, 2016 EUR (€)	Dec. 16, 2015 USD ($)	Dec. 16, 2015 EUR (€) item € / shares	Jan. 19, 2016 EUR (€)	Dec. 31, 2015 EUR (€)	Dec. 31, 2016 EUR (€)	Dec. 31, 2017 EUR (€)	Dec. 31, 2016 EUR (€)	Dec. 31, 2015 EUR (€)	Jan. 31, 2016 item
Disclosure of fair value measurement of assets [line items]
Share subscription increase							€ 363,924,000	€ 326,271,000	€ 278,703,000
Deferred income					€ 39,806,000	€ 285,612,000	219,892,000	285,612,000	39,806,000
Fair value at inception				€ 419,052,000			1,057,309,000	419,052,000
Movement of period (recognized in the income statement)								57,479,000	(30,632,000)
Fair value at the end					419,052,000	1,057,309,000	€ 1,257,329,000	1,057,309,000	419,052,000
Number of counterparties \| item			2
Number of valuation date \| item										2
Gilead Sciences, Inc
Disclosure of fair value measurement of assets [line items]
Payment composed of license fee and equity investment \| $		$ 725
Share subscription increase	€ 392,120,658	$ 425
Price per share including issuance premium \| € / shares			€ 58.00
Derivative financial asset instrument strike price (Euro per share) \| € / shares			€ 58.00
Fair value of derivative financial asset in case of recalculation					8,367,000				8,367,000
Gilead Sciences, Inc \| At fair value
Disclosure of fair value measurement of assets [line items]
Fair value at inception			€ 39,003,000	8,371,000	39,003,000	65,850,000		€ 8,371,000
Movement of period (recognized in the income statement)				57,479,000	(30,632,000)
Derecognition of the financial asset through the share premium account						€ (65,850,000)
Fair value at the end	65,850,000			65,850,000	€ 8,371,000				€ 8,371,000
Gilead Sciences, Inc \| Recurring fair value measurement
Disclosure of fair value measurement of assets [line items]
Net fair value gain	26,800,000
Derivatives [member] \| Gilead Sciences, Inc \| Recurring fair value measurement
Disclosure of fair value measurement of assets [line items]
Offsetting short-term financial asset (derivative)	€ 65,900,000			€ 65,900,000