The percentage of annual cash bonus on gross salaries.

No definition available.

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- Definition

The percentage of extraordinary bonus on gross salaries.

+ References

No definition available.

+ Details

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- Definition

The amount of compensation to key management personnel in the form of cash bonus benefits

+ References

No definition available.

+ Details

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- Definition

The percentage of increase in base salary during the period.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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- Definition

Na.

+ References

No definition available.

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- Definition

The period for which the shares has to be held.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Value of units granted in share based payment arrangement based on fixed annual base fees.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Value of units granted in share based payment arrangement based on percentage of fixed annual base fees.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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- Definition

The value of warrants portion on the total grants in the combination of restricted stock units and warrants.

+ References

No definition available.

+ Details

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- Definition

The period for which the warrants has to be held for locked.

+ References

No definition available.

+ Details

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- Definition

The amount of compensation to key management personnel in the form of post-employment benefits. [Refer: Key management personnel of entity or parent [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
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Balance Type:	debit
Period Type:	duration

- Definition

The amount of compensation to key management personnel in the form of share-based payments. [Refer: Key management personnel of entity or parent [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 24
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of other equity instruments (ie other than share options) granted in a share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 2
-IssueDate 2019-01-01
-Paragraph 47
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2019-en-r&anchor=para_47_b&doctype=Standard
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Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 2
-IssueDate 2019-01-01
-Paragraph 45
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2019-en-r&anchor=para_45&doctype=Standard
-URIDate 2019-03-27

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Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value at the measurement date of granted equity instruments other than share options. [Refer: Weighted average [member]]

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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- Details

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- Details

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Name:	ifrs-full_GeographicalAreasAxis=ifrs-full_ForeignCountriesMember
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- Details

Name:	ifrs-full_CategoriesOfRelatedPartiesAxis=gmab_IfrsChiefExecutiveOfficerMember
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OTHER DISCLOSURES - Remuneration To Executive Management (Details) € in Millions, kr in Millions, $ in Millions						12 Months Ended
	Jan. 01, 2019	Jul. 01, 2018	Jan. 01, 2018	Jul. 01, 2017	Jan. 01, 2017	Dec. 31, 2019 EUR (€) EquityInstruments	Dec. 31, 2019 USD ($) EquityInstruments	Dec. 31, 2019 DKK (kr) EquityInstruments	Dec. 31, 2018 DKK (kr) EquityInstruments	Dec. 31, 2017 DKK (kr) EquityInstruments
Remuneration to the Executive Management
Amount received by management								kr 38.0	kr 32.0	kr 28.0
Extraordinary bonus percentage						15.00%	15.00%	15.00%
Cash bonus								kr 15.0	kr 11.0
Value of warrants granted based on compensation								kr 25.0
Value of warrants portion in a total grant						25.00%	25.00%	25.00%	50.00%
Share-based compensation expenses								kr 1.0	kr 1.0	kr 1.0
RSUs
Remuneration to the Executive Management
Granted \| EquityInstruments						116,742	116,742	116,742	102,639	65,951
Minimum
Remuneration to the Executive Management
Percentage of annual cash bonus						60.00%	60.00%	60.00%
Maximum
Remuneration to the Executive Management
Percentage of annual cash bonus						100.00%	100.00%	100.00%
Executive Management
Remuneration to the Executive Management
Value of shares granted on percentage of compensation						400.00%	400.00%	400.00%	200.00%
Share-based compensation expenses							$ 32.6	kr 33.0	kr 27.4	kr 22.7
Warrants additional lock in period						2 years	2 years	2 years
Executive Management \| Warrants
Remuneration to the Executive Management
Granted \| EquityInstruments									50,464
Executive Management \| RSUs
Remuneration to the Executive Management
Granted \| EquityInstruments						25,793	25,793	25,793	18,020	19,599
Weighted average fair value at measurement date, other equity instruments granted								kr 42.0	kr 37.0
Executive Management \| Minimum
Remuneration to the Executive Management
Share holding period						5 years	5 years	5 years
Executive Management \| Maximum
Remuneration to the Executive Management
Value of shares granted on percentage of compensation						200.00%	200.00%	200.00%
Executive Management \| Maximum \| Foreign countries
Remuneration to the Executive Management
Value of shares granted on percentage of compensation						400.00%	400.00%	400.00%
CEO
Remuneration to the Executive Management
Percentage of increase in base salary	3.00%		3.00%
Amount received by management \| €						€ 0.5
CFO
Remuneration to the Executive Management
Percentage of increase in base salary	3.00%				3.00%
Amount received by management \| $							$ 0.1
CDO
Remuneration to the Executive Management
Percentage of increase in base salary	10.00%	3.00%		3.00%