Reinsurance and Indemnification - Kentucky Earthquake Excess of Loss Catastrophe Reinsurance Contracts (Narrative) (Details) - Kentucky Agreement $ in Millions	12 Months Ended
Dec. 31, 2024 USD ($) reinstatement
Reinsurance Retention Policy [Line Items]
Limit of aggregate losses under aggregate excess agreement	$ 27
Retention amount for catastrophe reinsurance agreement contracts	$ 2
Traditional Market
Reinsurance Retention Policy [Line Items]
Number of reinstatements each year for each contract \| reinstatement	1

Represents the number of reinstatements each year for each contract.

No definition available.

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- Definition

The limit of aggregated losses per contract year beyond which coverage provided by an aggregate excess agreement applies.

+ References

No definition available.

+ Details

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Namespace Prefix:	all_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the retention amount of catastrophe reinsurance agreement contracts.

+ References

No definition available.

+ Details

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Namespace Prefix:	all_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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.

+ 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

+ Details

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- Details

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- Details

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