Reinsurance - Schedule of External Quota Share Agreements (Details) - Quota Share Agreement	9 Months Ended
Sep. 30, 2026
Ceded Credit Risk [Line Items]
Cession Rate	45.00%
External Third-Party \| AmCoastal \| Reinsurance Contract [Axis]: 06/01/2024 - 05/31/2026 \| Florida
Ceded Credit Risk [Line Items]
Cession Rate	20.00%
External Third-Party \| AmCoastal \| Reinsurance Contract [Axis]: 06/01/2026 - 05/31/2028 \| Florida
Ceded Credit Risk [Line Items]
Cession Rate	15.00%

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 825
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477351/944-825-50-1B

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 825
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477351/944-825-50-1B

Name:	us-gaap_CededCreditRiskLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration