XML 57 R31.htm IDEA: XBRL DOCUMENT v3.21.2

Share-Based Instruments - Part 3 (Details) - Restricted Stock Units Program - DKK (kr)		6 Months Ended		12 Months Ended
	Feb. 23, 2021	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	Apr. 30, 2021	Mar. 31, 2019	Mar. 31, 2016
Disclosure of terms and conditions of share-based payment arrangement [line items]
Amount of stock repurchase plan authorized					kr 500,000	kr 500,000	kr 500,000
Number of shares authorized to be repurchased	200,000				500,000	500,000	500,000
Repurchased shares			0	225,000
Repurchased values				kr 225,000
Percentage of share capital	0.30%
Treasury stock shares		299,206
Purchase of treasury shares	kr (447,000,000)

X

- Definition

Amount of stock repurchase plan authorized.

+ References

No definition available.

+ Details

Name:	gmab_IfrsStockRepurchaseProgramAuthorizedAmount
Namespace Prefix:	gmab_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

Name:	gmab_IfrsStockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
Namespace Prefix:	gmab_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

No definition available.

+ Details

Name:	gmab_IfrsStockRepurchasedDuringPeriodShares
Namespace Prefix:	gmab_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

No definition available.

+ Details

Name:	gmab_IfrsStockRepurchasedDuringPeriodValue
Namespace Prefix:	gmab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The number of shares that has been treasury stock.

+ References

No definition available.

+ Details

Name:	gmab_IfrsTreasuryStockShares
Namespace Prefix:	gmab_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Percentage of share capital.

+ References

No definition available.

+ Details

Name:	gmab_PercentageOfShareCapital
Namespace Prefix:	gmab_
Data Type:	num:percentItemType
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_DisclosureOfTermsAndConditionsOfSharebasedPaymentArrangementLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The decrease in equity resulting from the purchase of treasury shares. [Refer: Treasury shares]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2020-01-01
-Paragraph 106
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_106_d&doctype=Standard
-URIDate 2020-01-01

+ Details

Name:	ifrs-full_PurchaseOfTreasuryShares
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	gmab_IfrsShareRepurchaseProgramAxis=gmab_RestrictedStockUnitsProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: