Short Duration Contracts - Percentage annual payout - all segments (Details)	Dec. 31, 2025
Insurance \| Property, energy, marine and aviation
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year One	23.00%
Year Two	41.40%
Year Three	18.20%
Year Four	8.90%
Year Five	3.30%
Year Six	1.00%
Year Seven	0.00%
Year Eight	1.10%
Year Nine	(0.10%)
Year Ten	0.10%
Insurance \| Third party occurrence business
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year One	3.70%
Year Two	10.10%
Year Three	12.40%
Year Four	13.40%
Year Five	11.30%
Year Six	10.50%
Year Seven	6.10%
Year Eight	5.00%
Year Nine	4.60%
Year Ten	2.00%
Insurance \| Third party claims-made business
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year One	4.70%
Year Two	16.10%
Year Three	16.30%
Year Four	12.00%
Year Five	13.30%
Year Six	11.80%
Year Seven	6.40%
Year Eight	7.70%
Year Nine	1.30%
Year Ten	2.40%
Insurance \| Multi-line and other specialty
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year One	31.20%
Year Two	29.00%
Year Three	11.00%
Year Four	8.50%
Year Five	5.60%
Year Six	3.70%
Year Seven	2.10%
Year Eight	1.40%
Year Nine	1.10%
Year Ten	0.40%
Reinsurance \| Casualty
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year One	2.90%
Year Two	8.20%
Year Three	11.80%
Year Four	12.10%
Year Five	11.50%
Year Six	7.80%
Year Seven	7.60%
Year Eight	6.80%
Year Nine	4.70%
Year Ten	3.00%
Reinsurance \| Property catastrophe
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year One	(62.40%)
Year Two	110.10%
Year Three	(23.80%)
Year Four	138.80%
Year Five	(24.80%)
Year Six	17.40%
Year Seven	(4.80%)
Year Eight	1.00%
Year Nine	2.20%
Year Ten	5.70%
Reinsurance \| Property excluding property catastrophe
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year One	20.90%
Year Two	37.00%
Year Three	14.50%
Year Four	7.30%
Year Five	5.40%
Year Six	1.80%
Year Seven	1.20%
Year Eight	0.70%
Year Nine	1.10%
Year Ten	(0.70%)
Reinsurance \| Marine and aviation
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year One	1.80%
Year Two	24.30%
Year Three	19.80%
Year Four	15.00%
Year Five	12.20%
Year Six	6.40%
Year Seven	2.00%
Year Eight	1.10%
Year Nine	1.10%
Year Ten	6.20%
Reinsurance \| Specialty
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year One	26.20%
Year Two	28.20%
Year Three	14.60%
Year Four	6.70%
Year Five	5.40%
Year Six	3.80%
Year Seven	1.20%
Year Eight	0.50%
Year Nine	0.00%
Year Ten	0.10%
Mortgage
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Year One	4.10%
Year Two	26.00%
Year Three	26.00%
Year Four	14.30%
Year Five	9.60%
Year Six	4.20%
Year Seven	2.60%
Year Eight	1.30%
Year Nine	0.70%
Year Ten	0.50%

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- Definition

Percentage of average annual payout, after reinsurance, in the eighth year after a claim is incurred, beginning with the earliest accident year disclosed for short-duration insurance contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 9F
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480046/944-40-55-9F

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 4G
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480081/944-40-50-4G

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- Definition

Percentage of average annual payout, after reinsurance, in the fifth year after a claim is incurred, beginning with the earliest accident year disclosed for short-duration insurance contracts.

+ References

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Percentage of average annual payout, after reinsurance, in the fourth year after a claim is incurred, beginning with the earliest accident year disclosed for short-duration insurance contracts.

+ References

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- Definition

Percentage of average annual payout, after reinsurance, in the ninth year after a claim is incurred, beginning with the earliest accident year disclosed for short-duration insurance contracts.

+ References

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- Definition

Percentage of average annual payout, after reinsurance, in the first year after a claim is incurred, beginning with the earliest accident year disclosed for short-duration insurance contracts.

+ References

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- Definition

Percentage of average annual payout, after reinsurance, in the seventh year after a claim is incurred, beginning with the earliest accident year disclosed for short-duration insurance contracts.

+ References

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Percentage of average annual payout, after reinsurance, in the sixth year after a claim is incurred, beginning with the earliest accident year disclosed for short-duration insurance contracts.

+ References

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- Definition

Percentage of average annual payout, after reinsurance, in the tenth year after a claim is incurred, beginning with the earliest accident year disclosed for short-duration insurance contracts.

+ References

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- Definition

Percentage of average annual payout, after reinsurance, in the third year after a claim is incurred, beginning with the earliest accident year disclosed for short-duration insurance contracts.

+ References

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Percentage of average annual payout, after reinsurance, in the second year after a claim is incurred, beginning with the earliest accident year disclosed for short-duration insurance contracts.

+ References

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