v3.20.1

Operating costs - Summary of general and administrative expenses (Details) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating costs
Personnel costs and directors fees	€ (51,906)	€ (25,495)	€ (17,756)
Depreciation	(1,513)	(513)	(606)
Legal and professional fees	(11,775)	(4,284)	(2,427)
Other operating expenses	(8,506)	(5,339)	(3,626)
Total general and administrative expenses	€ (73,701)	€ (35,631)	€ (24,415)

X

- Definition

The amount of depreciation expense incurred during period, included in general and administrative expenses.

+ References

No definition available.

+ Details

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

X

- Definition

The amount of legal and professional fees incurred during period, included in general and administrative expenses.

+ References

No definition available.

+ Details

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

X

- Definition

Amount of general and administrative other operating expenses.

+ References

No definition available.

+ Details

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

X

- Definition

Amount of general and administrative personnel costs and director fees.

+ References

No definition available.

+ Details

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

X

- References

No definition available.

+ Details

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

X

- Definition

The amount of expense relating to general and administrative activities of the entity.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2019-01-01
-Paragraph 112
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_112_c&doctype=Standard
-URIDate 2019-03-27

+ Details

Name:	ifrs-full_GeneralAndAdministrativeExpense
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration