Personnel expenses - Plan assets (Details) - SEK (kr) kr in Millions	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disclosure of net defined benefit liability (asset) [line items]
Debt instruments	kr 101	kr 104	kr 85
Other Investments	29	34	38
Properties	29	28	27
Total plan assets	195	200	181
Sweden
Disclosure of net defined benefit liability (asset) [line items]
Equity investments	8	6	5
Foreign equity investments
Disclosure of net defined benefit liability (asset) [line items]
Equity investments	kr 27	kr 28	kr 26

The amount instruments representing debt (rather than equity) contribute to the fair value of defined benefit plan assets. [Refer: Plan assets, at fair value; Defined benefit plans [domain]]

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 19
-IssueDate 2025-01-01
-Paragraph 142
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2025-en-r&anchor=para_142_c&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 208
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_208_b&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 208
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_208_b&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_DebtInstrumentsAmountContributedToFairValueOfPlanAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with members defined in one or many axes of the table.

+ References

No definition available.

+ Details

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

- Definition

The amount instruments representing equity (rather than debt) contribute to the fair value of defined benefit plan assets. [Refer: Plan assets, at fair value; Defined benefit plans [domain]]

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 19
-IssueDate 2025-01-01
-Paragraph 142
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2025-en-r&anchor=para_142_b&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 208
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_208_a&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 208
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_208_a&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_EquityInstrumentsAmountContributedToFairValueOfPlanAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount other types of assets not separately disclosed contribute to the fair value of defined benefit plan assets. [Refer: Plan assets, at fair value; Defined benefit plans [domain]]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2025-01-01
-Paragraph 142
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2025-en-r&anchor=para_142&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 208
-Subparagraph d
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_208_d&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 208
-Subparagraph d
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_208_d&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_OtherAssetsAmountContributedToFairValueOfPlanAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The fair value of defined benefit plan assets. Plan assets comprise assets held by a long-term employee benefit fund and qualifying insurance policies. [Refer: At fair value [member]]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2025-01-01
-Paragraph 57
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2025-en-r&anchor=para_57_a&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_PlanAssetsAtFairValue
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount real estate contributes to the fair value of defined benefit plan assets. [Refer: Plan assets, at fair value; Defined benefit plans [domain]]

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 19
-IssueDate 2025-01-01
-Paragraph 142
-Subparagraph d
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2025-en-r&anchor=para_142_d&doctype=Standard
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 208
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_208_c&doctype=Standard
-URIDate 2025-03-27

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph 208
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_208_c&doctype=Standard
-URIDate 2025-03-27

+ Details

Name:	ifrs-full_PropertyAmountContributedToFairValueOfPlanAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	ifrs-full_GeographicalAreasAxis=ifrs-full_CountryOfDomicileMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_GeographicalAreasAxis=ifrs-full_ForeignCountriesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: