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

Represents the number of reinstatements each year for each contract.

No definition available.

Name:	all_CatastropheInsuranceNumberOfReinstatementsPerYear
Namespace Prefix:	all_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Catastrophe Insurance, Quota Share Basis, Percentage

No definition available.

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

Catastrophe Reinsurance Aggregate Annual Loss Limit

No definition available.

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

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

No definition available.

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

Catastrophe Reinsurance Aggregate, Loss Limit Per Contract Year, Percent

No definition available.

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

Represents the number of layers subject to reinstatement in which catastrophe reinsurance agreement contracts are placed.

No definition available.

Name:	all_CatastropheReinsuranceAgreementContractNumberofLayersSubjecttoReinstatement
Namespace Prefix:	all_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the period of catastrophe reinsurance agreement contract.

No definition available.

Name:	all_CatastropheReinsuranceAgreementContractTerm
Namespace Prefix:	all_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the number of limits as per catastrophe reinsurance agreement contracts.

No definition available.

Name:	all_CatastropheReinsuranceAgreementContractsNumberofLimits
Namespace Prefix:	all_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the retention amount of catastrophe reinsurance agreement contracts.

No definition available.

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

Catastrophe Reinsurance Agreement Term, Layer

No definition available.

Name:	all_CatastropheReinsuranceAgreementTermLayer
Namespace Prefix:	all_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The number of separate catastrophe reinsurance agreements coordinating coverage for personal property excess catastrophe losses.

No definition available.

Name:	all_CatastropheReinsuranceNumberOfAgreements
Namespace Prefix:	all_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the number of states covered under the reinsurance agreement.

No definition available.

Name:	all_NumberOfStatesCoveredUnderReinsuranceAgreement
Namespace Prefix:	all_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the number of reinsurance contracts under the agreement.

No definition available.

Name:	all_ReinsuranceContractsNumber
Namespace Prefix:	all_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Amount of earned premiums ceded to other entities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.1)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 605
-Section 50
-Paragraph 1
-Subparagraph (b),(c)(2)
-URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 605
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6486662&loc=d3e27175-158546

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
-Section S99
-Paragraph 2
-Subparagraph (SX 210.12-17)
-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915

Name:	us-gaap_CededPremiumsEarned
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6480758&loc=d3e6824-158387

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6485522&loc=d3e21409-158489

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-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=6879938&loc=d3e572229-122910

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

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.

No definition available.

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

Name:	us-gaap_CededCreditRiskAxis=all_CastleKeyInsuranceCompanyAndSubsidiariesAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_CatastropheReinsuranceFirstFourLayersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_CatastropheReinsuranceSixAndNinthLayerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_PropertyClaimsServicesExcessCatastropheReinsuranceAgreementCoverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_NewJerseyAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_NewJerseyAgreementContractOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_NewJerseyAgreementContractTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_NewJerseyAgreementContractThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_PennsylvaniaAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_PennsylvaniaAgreementThreeLimitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_PennsylvaniaAgreementTwoLimitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_KentuckyAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_ESEarthquakeAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_FloridaExcessCatastropheReinsuranceAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_CatastropheReinsuranceFirstFiveLayersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_FloridaHurricaneCatastropheFundMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_CatastropheReinsuranceSixthLayerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_CatastropheReinsuranceLayerOnetoSixMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_CatastropheReinsuranceNinthLayerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_PropertyClaimsServicesClassBExcessCatastropheReinsuranceAgreementCoverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_PropertyClaimsServicesClassAExcessCatastropheReinsuranceAgreementCoverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_PropertyClaimsServicesClassDExcessCatastropheReinsuranceAgreementCoverageWithPortionOfSeventhLayerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_PropertyClaimsServicesClassCExcessCatastropheReinsuranceAgreementCoverageWithPortionOfNinthLayerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CededCreditRiskAxis=all_PropertyClaimsServicesClassBExcessCatastropheReinsuranceAgreementCoverageWithPortionOfTenthLayerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ReinsurancePolicyTypeAxis=all_A20141PCSMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ReinsurancePolicyTypeAxis=all_GapFillMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: