v3.20.1

Income Taxes - Schedule of tax liabilities (Details) € in Thousands	12 Months Ended
	Dec. 31, 2019 EUR (€) subsidiary	Dec. 31, 2018 EUR (€) subsidiary	Dec. 31, 2017 EUR (€)
Income Taxes
Current tax payable	€ 2,037	€ 1,175	€ 865
Total tax liabilities	€ 2,037	€ 1,175	€ 865
Number of subsidiaries operating on a cost plus basis | subsidiary	4	5

X

- Definition

The amount of tax liabilities.

+ References

No definition available.

+ Details

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

X

- Definition

Represents the number of subsidiaries operating on a cost plus basis.

+ References

No definition available.

+ Details

Name:	glpg_NumberOfSubsidiaries
Namespace Prefix:	glpg_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The amount of current tax for current and prior periods to the extent unpaid. Current tax is the amount of income taxes payable (recoverable) in respect of the taxable profit (tax loss) for a period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2019-01-01
-Paragraph 54
-Subparagraph n
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_54_n&doctype=Standard
-URIDate 2019-03-27

+ Details

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

X

- References

No definition available.

+ Details

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