Equity - Reserves - Unavailable Reserve (Details) - EUR (€) € in Millions	Dec. 31, 2025	Dec. 31, 2024
Spanish companies other than parent
Equity
Restricted reserves	€ 30	€ 19

Reserves, restricted reserves, development costs, carrying value, pending amortization, in accordance with applicable legislation.

No definition available.

Name:	grfs_ReservesRestrictedReservesDevelopmentCostsCarryingValuePendingAmortizationInAccordanceWithApplicableLegislation
Namespace Prefix:	grfs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant