Operating assets and liabilities - Retirement benefit obligations - Key assumptions used for valuation and sensitivity analysis (Details) - DKK (kr) kr in Millions	Dec. 31, 2020	Dec. 31, 2019
Actuarial assumption of discount rates
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Discount rate	1.00%	1.30%
Increase (decrease) in defined benefit obligation due to reasonably possible increase in actuarial assumption	kr (403)	kr (366)
Increase (decrease) in defined benefit obligation due to reasonably possible decrease in actuarial assumption	kr 523	kr 465
Percentage of reasonably possible increase in actuarial assumption	1.00%
Percentage of reasonably possible decrease in actuarial assumption	1.00%
Actuarial assumption of expected rates of salary increases
Disclosure of sensitivity analysis for actuarial assumptions [line items]
Future remuneration	2.20%	2.40%
Increase (decrease) in defined benefit obligation due to reasonably possible increase in actuarial assumption	kr 116	kr 105
Increase (decrease) in defined benefit obligation due to reasonably possible decrease in actuarial assumption	kr (101)	kr (94)
Percentage of reasonably possible increase in actuarial assumption	1.00%
Percentage of reasonably possible decrease in actuarial assumption	1.00%

The discount rate used as the significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit obligation, at present value; Actuarial assumptions [member]]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2019-01-01
-Paragraph 144
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-URIDate 2019-03-27

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- Definition

The expected rate of salary increases used as a significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit plans [member]; Defined benefit obligation, at present value; Actuarial assumptions [member]]

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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.

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- Definition

The increase (decrease) in a defined benefit obligation that would have been caused by a decrease in a significant actuarial assumption that was reasonably possible at the end of the reporting period. [Refer: Actuarial assumptions [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2019-01-01
-Paragraph 145
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=19&code=ifrs-tx-2019-en-r&anchor=para_145_a&doctype=Standard
-URIDate 2019-03-27

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- Definition

The increase (decrease) in a defined benefit obligation that would have been caused by an increase in a significant actuarial assumption that was reasonably possible at the end of the reporting period. [Refer: Actuarial assumptions [member]]

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The reasonably possible percentage of the decrease in the actuarial assumption used to determine the present value of defined benefit obligation. [Refer: Actuarial assumptions [member]]

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The reasonably possible percentage of the increase in the actuarial assumption used to determine the present value of defined benefit obligation. [Refer: Actuarial assumptions [member]]

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