The increase (decrease) in equity as a result of decrease in designated risk component.

No definition available.

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

- Definition

The increase (decrease) in equity as a result of increase in designated risk component.

+ References

No definition available.

+ Details

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

- Definition

The increase (decrease) in net book value as a result of change in a designated risk component that was reasonably possible at the end of the reporting period. Excludes defined benefit plan obligations.

+ References

No definition available.

+ Details

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

- Definition

The increase (decrease) in profit and loss as a result of decrease in designated risk component.

+ References

No definition available.

+ Details

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

- Definition

The increase (decrease) in profit and loss as a result of increase in designated risk component.

+ References

No definition available.

+ Details

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

- Definition

The reasonably possible percentage of change in the designated risk component used to determine the value of the financial instrument. Excludes defined benefit plan obligations.

+ References

No definition available.

+ Details

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Namespace Prefix:	glpg_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The reasonably possible percentage of the decrease in the designated risk component used to determine the value of the financial instrument. Excludes defined benefit plan obligations.

+ References

No definition available.

+ Details

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Namespace Prefix:	glpg_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The reasonably possible percentage of the increase in the designated risk component used to determine the value of the financial instrument. Excludes defined benefit plan obligations

+ References

No definition available.

+ Details

Name:	glpg_PercentageOfReasonablyPossibleIncreaseInRiskAssumption
Namespace Prefix:	glpg_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table.

+ References

No definition available.

+ Details

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

- Details

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

- Details

Name:	ifrs-full_TypesOfRisksAxis=ifrs-full_CurrencyRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CurrencyAxis=glpg_EuroUsdExchangeRateValueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CurrencyAxis=glpg_EuroGbpExchangeRateValueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CurrencyAxis=glpg_EuroChFrancsExchangeRateValueMember
Namespace Prefix:
Data Type:	na
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Financial risk management - Interest rate risk and foreign exchange risk (Details) - EUR (€)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Interest rate risk
Financial risk management
Increase in interest rates	100.00%
Decrease in interest rates	(100.00%)
Increase (Decrease) In Equity due to increase in interest rates.	€ 30,000,000	€ 33,200,000	€ 36,800,000
Increase (Decrease) In equity due to decrease in interest rates.	(30,000,000)	(33,200,000)	(36,800,000)
Increase (Decrease) in profit or loss due to increase in interest rate.	30,000,000	33,200,000	36,800,000
Increase (Decrease) in profit or loss due to decrease in interest rate	€ (30,000,000)	€ (33,200,000)	€ (36,800,000)
Foreign exchange risk
Financial risk management
Percentage of change in risk assumption	10.00%	10.00%	10.00%	10.00%
Euros - U.S. Dollars Exchange rate value \| Foreign exchange risk
Financial risk management
Increase (Decrease) in net book value	€ (182,651,000)	€ (70,387,000)	€ (78,013,000)
Euros - GB Pounds Exchange rate value \| Foreign exchange risk
Financial risk management
Increase (Decrease) in net book value	62,000	31,000	666,000
Euros - CH Francs Exchange rate value \| Foreign exchange risk
Financial risk management
Increase (Decrease) in net book value	€ 774,000	€ 280,000	€ 385,000