Leasing - Contractual flows of lease liability and costs (Details) - SEK (kr) kr in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Leases
Discounting effect	kr (1)	kr (1)
Closing balance	86	98	kr 125
Cash outflow	43	40
Within 1 year
Leases
Undiscounted lease payments	31	28
Between 1 and 5 years
Leases
Undiscounted lease payments	56	71
More than 5 years
Leases
Undiscounted lease payments	kr 0	kr 0

The cash outflow for leases.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 16
-IssueDate 2025-01-01
-Paragraph 53
-Subparagraph g
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=16&code=ifrs-tx-2025-en-r&anchor=para_53_g&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 115
-Subparagraph f
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_115_f&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 115
-Subparagraph f
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_115_f&doctype=Standard
-URIDate 2025-03-27

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