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Reinsurance - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Effects of Reinsurance [Line Items]
Percentage of NFIP	100.00%		100.00%
Ceded loss and loss expense	$ 434,670	$ 103,573	$ 579,255	$ 213,161
Effect in direct loss and loss expense incurred			182,748	(5,782)
Casualty lines
Effects of Reinsurance [Line Items]
Effect in direct loss and loss expense incurred			211,000	$ (16,500)
National Flood Insurance Program
Effects of Reinsurance [Line Items]
Increase of NFIP reserves	$ 232,800
Total rated reinsurers
Effects of Reinsurance [Line Items]
Change in reinsurance recoverable gross			155,900
Federal and state pools
Effects of Reinsurance [Line Items]
Change in reinsurance recoverable gross			$ 244,600

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Change in the amount of reduction of provision for policy benefits and costs incurred for policies ceded.

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Change In Reinsurance Recoverable, Gross

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Percentage Of Unpaid NFIP Claims Ceded By Federal Government

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Amount of reduction of provision for policy benefits and costs incurred for policies ceded.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479838/944-20-50-3

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(5))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1

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Amount, after effects of reinsurance, of expense (reversal of expense) for claims incurred in prior reporting periods and related claims settlement costs.

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Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480046/944-40-55-7

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