Segment Reporting - Additional Information (Details)	12 Months Ended
Dec. 31, 2019 location area
Segment Reporting
Number of areas Group companies are divided into \| area	4
Geographical information
Number of geographical areas \| location	4

The number of areas Group companies are divided into. They include the industrial area, the commercial area, the services area and the research area. Within each of these areas, activities are organized based on the nature of the products and services manufactured and marketed.

No definition available.

Name:	grfs_GroupCompaniesNumberOfAreas
Namespace Prefix:	grfs_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration