Lease liabilities - Movements of lease liabilities (Details) - EUR (€) € in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Leases liabilities
Balance at beginning of period	€ 572	€ 1,051
Repayment of lease liabilities	(491)	(733)	€ (564)
New lease contracts	7,241	254
Disposal of subsidiary	(123)	0
Sub-total - Other changes	7,118	254
Balance at end of period	€ 7,199	€ 572	€ 1,051

The amount of additions in new contract.

No definition available.

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Namespace Prefix:	afmd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The impact on lease liabilities from disposal of subsidiary.

+ References

No definition available.

+ Details

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Namespace Prefix:	afmd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The total impact on lease liabilities from other changes.

+ References

No definition available.

+ Details

Name:	afmd_Totalleaseliabilitiesotherchanges
Namespace Prefix:	afmd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of liabilities related to the entity's leases. Lease is a contract, or part of a contract, that conveys the right to use an underlying asset for a period of time in exchange for consideration.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 16
-IssueDate 2023-01-01
-Paragraph 47
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2023-en-r&anchor=para_47_b&doctype=Standard
-URIDate 2023-03-23

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash outflow for payment of lease liabilities, classified as financing activities. [Refer: Lease liabilities]

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 7
-IssueDate 2023-01-01
-Paragraph 17
-Subparagraph e
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=7&code=ifrs-tx-2023-en-r&anchor=para_17_e&doctype=Standard
-URIDate 2023-03-23

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.

+ Details

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration