Property Casualty Loss and Loss Expense - Average Annual Payout (Details)	Dec. 31, 2024
Commercial Insurance \| Commercial Casualty Line
Short-duration Insurance Contracts, Historical Claims Duration
1	6.00%
2	13.20%
3	18.80%
4	16.80%
5	14.00%
6	8.70%
7	6.00%
8	4.60%
9	3.00%
10	2.90%
Commercial Insurance \| Workers' Compensation Line
Short-duration Insurance Contracts, Historical Claims Duration
1	24.10%
2	24.80%
3	11.20%
4	6.70%
5	3.80%
6	2.00%
7	1.50%
8	0.70%
9	0.80%
10	0.30%
Commercial Insurance \| Commercial Auto Line
Short-duration Insurance Contracts, Historical Claims Duration
1	38.50%
2	19.30%
3	15.20%
4	11.80%
5	7.60%
Commercial Insurance \| Commercial Property Line
Short-duration Insurance Contracts, Historical Claims Duration
1	59.60%
2	30.60%
3	5.10%
4	1.60%
5	1.10%
Personal Insurance \| Personal Auto
Short-duration Insurance Contracts, Historical Claims Duration
1	64.50%
2	16.60%
3	8.00%
4	5.80%
5	2.60%
Personal Insurance \| Homeowner
Short-duration Insurance Contracts, Historical Claims Duration
1	64.70%
2	26.70%
3	4.20%
4	1.90%
5	0.80%
Excess and Surplus Lines Insurance
Short-duration Insurance Contracts, Historical Claims Duration
1	9.00%
2	12.30%
3	16.20%
4	15.70%
5	14.30%
6	10.30%
7	6.30%
8	2.70%
9	3.80%
10	2.00%

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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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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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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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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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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.

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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.

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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.

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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.

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