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Supplementary Information of Average Historical Claims (Detail) | Dec. 31, 2022
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Commercial Specialty | Property Insurance |  |
Short-duration Insurance Contracts, Historical Claims Duration [Line Items] |  |
Average annual percentage payout of incurred claims by age, net of reinsurance year one | 61.00% |
Average annual percentage payout of incurred claims by age, net of reinsurance year two | 28.90% |
Average annual percentage payout of incurred claims by age, net of reinsurance year three | 4.70% |
Commercial Specialty | Casualty Insurance |  |
Short-duration Insurance Contracts, Historical Claims Duration [Line Items] |  |
Average annual percentage payout of incurred claims by age, net of reinsurance year one | 7.70% |
Average annual percentage payout of incurred claims by age, net of reinsurance year two | 17.40% |
Average annual percentage payout of incurred claims by age, net of reinsurance year three | 19.30% |
Average annual percentage payout of incurred claims by age, net of reinsurance year four | 19.70% |
Average annual percentage payout of incurred claims by age, net of reinsurance year five | 12.20% |
Average annual percentage payout of incurred claims by age, net of reinsurance year six | 7.60% |
Average annual percentage payout of incurred claims by age, net of reinsurance year seven | 4.30% |
Average annual percentage payout of incurred claims by age, net of reinsurance year eight | 1.70% |
Average annual percentage payout of incurred claims by age, net of reinsurance year nine | 0.60% |
Average annual percentage payout of incurred claims by age, net of reinsurance year ten | 0.10% |
Reinsurance Operations | Casualty Insurance |  |
Short-duration Insurance Contracts, Historical Claims Duration [Line Items] |  |
Average annual percentage payout of incurred claims by age, net of reinsurance year one | 0.60% | [1]
Average annual percentage payout of incurred claims by age, net of reinsurance year two | 1.90% | [1]
Average annual percentage payout of incurred claims by age, net of reinsurance year three | 1.10% | [1]
Average annual percentage payout of incurred claims by age, net of reinsurance year four | 0.90% | [1]
Average annual percentage payout of incurred claims by age, net of reinsurance year five | 0.00% | [1]
Average annual percentage payout of incurred claims by age, net of reinsurance year six | 0.00% | [1]
Average annual percentage payout of incurred claims by age, net of reinsurance year seven | 0.00% | [1]
Average annual percentage payout of incurred claims by age, net of reinsurance year eight | 0.00% | [1]
Average annual percentage payout of incurred claims by age, net of reinsurance year nine | 0.00% | [1]
Average annual percentage payout of incurred claims by age, net of reinsurance year ten | 0.00% | [1]
Exited Lines Segment | Property Insurance |  |
Short-duration Insurance Contracts, Historical Claims Duration [Line Items] |  |
Average annual percentage payout of incurred claims by age, net of reinsurance year one | 73.90% |
Average annual percentage payout of incurred claims by age, net of reinsurance year two | 15.60% |
Average annual percentage payout of incurred claims by age, net of reinsurance year three | 5.30% |
Average annual percentage payout of incurred claims by age, net of reinsurance year four | 3.10% |
Exited Lines Segment | Casualty Insurance |  |
Short-duration Insurance Contracts, Historical Claims Duration [Line Items] |  |
Average annual percentage payout of incurred claims by age, net of reinsurance year one | 13.90% |
Average annual percentage payout of incurred claims by age, net of reinsurance year two | 20.30% |
Average annual percentage payout of incurred claims by age, net of reinsurance year three | 21.50% |
Average annual percentage payout of incurred claims by age, net of reinsurance year four | 17.30% |
Average annual percentage payout of incurred claims by age, net of reinsurance year five | 7.20% |
Average annual percentage payout of incurred claims by age, net of reinsurance year six | 5.80% |
Average annual percentage payout of incurred claims by age, net of reinsurance year seven | 1.90% |
Average annual percentage payout of incurred claims by age, net of reinsurance year eight | 0.10% |
[1] | May not be indicative of future average annual percentage payout of incurred claims due to a change in mix of business

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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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 4G -URI https://asc.fasb.org/extlink&oid=116884468&loc=SL65671329-158438 + Details
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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 Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 4G -URI https://asc.fasb.org/extlink&oid=116884468&loc=SL65671329-158438 + Details
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