The gross amount of life insurance in force as of the balance sheet date.

No definition available.

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Namespace Prefix:	all_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the carrying amount of the investments held by trust.

+ References

No definition available.

+ Details

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

- Definition

The percentage of morbidity risk ceded to reinsurers on term life insurance policies prior to October 2009.

+ References

No definition available.

+ Details

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Namespace Prefix:	all_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents reinsurance agreements entered with non associated reinsurers to limit the risk of mortality and morbidity losses.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of life insurance issued and outstanding ceded to other entity, as disclosed in supplementary reinsurance information. Includes, but is not limited to, dividend and adjustment to face value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 12
-Paragraph Column C
-Subsection 17

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
-Section S99
-Paragraph 2
-Subparagraph (SX 210.12-17(Column C))
-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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

No definition available.

+ Details

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

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Publisher FASB
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-Topic 275
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after valuation allowance, recoverable under reinsurance contracts including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.(a),6)
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Topic 944
-SubTopic 310
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=99404803&loc=d3e21409-158489

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

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Balance Type:
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- Details

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Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_ReinsurerConcentrationRiskMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=all_AllstateFinancialMember
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Data Type:	na
Balance Type:
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- Details

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- Details

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Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
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Period Type:

- Details

Name:	us-gaap_CededCreditRiskAxis=all_CitigroupAndScottishReMember
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- Details

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Reinsurance - Narrative (Details) $ in Millions	12 Months Ended
Reinsurance - Narrative (Details) $ in Millions	Dec. 31, 2020 USD ($) item	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Reinsurance recoverable
Number of unaffiliated reinsurers \| item	13
Reinsurance recoverable	$ 1,989	$ 2,490
Investments held by trust	1,560
Gross life insurance in force	435,850
Life insurance in force ceded to unaffiliated reinsurers	$ 63,697	$ 75,159	$ 83,166
Maximum
Reinsurance recoverable
Percent of morbidity risk ceded for term-life insurance policies (as a percent)	90.00%
A- \| Reinsurer Concentration Risk \| Allstate Financial
Reinsurance recoverable
Concentration risk, percentage	94.00%	78.00%
Non-affiliate
Reinsurance recoverable
Life insurance in force ceded to unaffiliated reinsurers	$ 63,700
Lincoln Benefit Life Company
Reinsurance recoverable
Investments held by trust	6,290
Prudential
Reinsurance recoverable
Reinsurance recoverable	1,280	$ 1,290
Citigroup Subsidiaries and Scottish Re
Reinsurance recoverable
Reinsurance recoverable	99	112
Scottish Re
Reinsurance recoverable
Reinsurance recoverable	$ 66	$ 73