The amount release from escrow.

No definition available.

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

- Definition

+ References

No definition available.

+ Details

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

- Definition

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

+ References

No definition available.

+ Details

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

- Definition

The maximum number of years the claim can be submitted.

+ References

No definition available.

+ Details

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

- Definition

Refers to the number of claims.

+ References

No definition available.

+ Details

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

- Definition

Refers to the given amount of months to achieve a desired target.

+ References

No definition available.

+ Details

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

- Definition

Represents the percentage of consideration held in escrow.

+ References

No definition available.

+ Details

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

- Definition

The amount of potential earn out due upon achievement of a revenue target.

+ References

No definition available.

+ Details

Name:	glpg_PotentialEarnOutDueUponAchievementOfRevenueTarget
Namespace Prefix:	glpg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The total settlement of claims.

+ References

No definition available.

+ Details

Name:	glpg_TotalSettlementAmountOfClaims
Namespace Prefix:	glpg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fair value, at acquisition date, of the consideration transferred in a business combination. [Refer: Business combinations [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 3
-IssueDate 2017-01-01
-Paragraph B64
-Subparagraph f
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=3&date=2017-03-01&anchor=para_B64_f&doctype=Appendix&seq=2
-URIDate 2017-03-09

+ Details

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

- Definition

The portion of consideration paid or received, consisting of cash and cash equivalents, in respect of both obtaining and losing control of subsidiaries or other businesses. [Refer: Subsidiaries [member]; Cash and cash equivalents; Consideration paid (received)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 7
-IssueDate 2017-01-01
-Paragraph 40
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2017-03-01&anchor=para_40_b&doctype=Standard
-URIDate 2017-03-09

+ Details

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

Contingent assets and liabilities (Details) € in Millions			6 Months Ended	12 Months Ended
Contingent assets and liabilities (Details) € in Millions	Apr. 01, 2016	Mar. 13, 2014 EUR (€)	Jun. 30, 2017 EUR (€)	Dec. 31, 2008 EUR (€)	Dec. 31, 2017 EUR (€) claim
Contingent assets and liabilities
Total consideration		€ 134.0
Consideration received in cash		129.0
Potential earn out due upon achievement of a revenue target		€ 5.0
Number of months to achieve revenue target		12 months
Percentage of consideration held in escrow		5.00%
Number of claims \| claim					4
Total settlement amount of claims					€ 1.3
Amount released from escrow			€ 6.6
Period a claim covered by tax deed can be introduced	5 years
Damages claimed				€ 1.5