Loss and Loss Adjustment Expenses - Summary of Average Annual Percentage Payout Of Incurred Losses By Age Net of Reinsurance For Worker's Compensation and general Liability (Unaudited) (Detail)	Dec. 31, 2024
Short-Duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net [Abstract]
Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance, Year 1	26.90%
Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance, Year 2	32.10%
Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance, Year 3	14.30%
Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance, Year 4	7.90%
Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance, Year 5	4.70%
Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance, Year 6	2.40%
Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance, Year 7	1.10%
Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance, Year 8	1.10%
Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance, Year 9	0.50%
Average Annual Percentage Payout of Incurred Claims by Age, Net of Reinsurance, Year 10	(0.50%)

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.

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.

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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.

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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.

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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.

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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 sixth year after a claim is incurred, beginning with the earliest accident year disclosed for short-duration insurance contracts.

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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.

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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.

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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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