XML 45 R19.htm IDEA: XBRL DOCUMENT v3.21.2

Basis of Presentation (Details)	Jun. 30, 2021 item
Basis of Presentation
Number of business unit	1

X

- References

No definition available.

+ Details

Name:	gmab_BasisOfPresentationAbstract
Namespace Prefix:	gmab_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Number of reporting units tested for impairment of goodwill. A reporting unit is an operating segment or one level below an operating segment.

+ References

No definition available.

+ Details

Name:	gmab_IfrsNumberOfReportingUnits
Namespace Prefix:	gmab_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant