v3.20.1

Significant accounting policies - Property, Plant and Equipment (Details)	12 Months Ended
	Dec. 31, 2019
Minimum | Installation and machinery
Disclosure of detailed information about property, plant and equipment
Useful lives	3 years
Minimum | Furniture, fixtures & vehicles
Disclosure of detailed information about property, plant and equipment
Useful lives	4 years
Maximum | Installation and machinery
Disclosure of detailed information about property, plant and equipment
Useful lives	15 years
Maximum | Furniture, fixtures & vehicles
Disclosure of detailed information about property, plant and equipment
Useful lives	10 years

X

- Definition

The useful lives used for property, plant and equipment, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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

X

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

X

- Details

Name:	ifrs-full_RangeAxis=ifrs-full_BottomOfRangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis=glpg_InstallationAndMachineryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ifrs-full_ClassesOfPropertyPlantAndEquipmentAxis=glpg_FurnitureFixturesAndVehiclesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ifrs-full_RangeAxis=ifrs-full_TopOfRangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: