SCHEDULE VI - SUPPLEMENTARY INFORMATION CONCERNING CONSOLIDATED PROPERTY-CASUALTY INSURANCE OPERATIONS (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
SCHEDULE VI - SUPPLEMENTARY INFORMATION CONCERNING CONSOLIDATED PROPERTY-CASUALTY INSURANCE OPERATIONS
Deferred policy acquisition costs	$ 1,820	$ 1,625	$ 1,396
Reserves for insurance claims and claims expense	22,923	21,857	21,288
Unearned premiums	11,640	10,917	10,345
Earned premiums	28,929	27,618	26,737
Net investment income	1,301	1,375	1,326
Claims and claims adjustment expense incurred:
Current Year Claims and Claims Adjustment Expense	19,512	18,032	19,149
Prior Year Claims and Claims Adjustment Expense	(84)	(121)	(665)
Amortization of deferred policy acquisition costs	3,875	3,674	3,483
Paid claims and claims adjustment expense	19,392	17,996	18,980
Premiums written	$ 29,614	$ 28,164	$ 27,027

Name:	all_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersClaimsAndClaimsAdjustmentExpenseAbstract
Namespace Prefix:	all_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

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

- Definition

Amount of amortization expense on deferred policy acquisition cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 235

-Section S99

-Paragraph 3

-Subparagraph (SX 210.12-18)

-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e575016-122915

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 18

-Article 12

+ Details

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

- Definition

Amount of expense for claims incurred in the current reporting period and related claims settlement costs.

+ References

+ Details

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

- Definition

Amount of deferred policy acquisition cost related to property-casualty insurance policy written.

+ References

+ Details

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

- Definition

Amount of property-casualty insurance premium revenue earned on insurance policies.

+ References

+ Details

Name:	us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersEarnedPremiums
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of net investment income earned by property-casualty insurance underwriter.

+ References

+ Details

Name:	us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersNetInvestmentIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Payments of claims and claims adjustment expenses during the period of a property-casualty insurance entity.

+ References

+ Details

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

- Definition

Amount of actual premium written by property-casualty insurance underwriter.

+ References

+ Details

Name:	us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPremiumsWritten
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of expense for claims incurred in prior reporting periods and related claims settlement costs.

+ References

+ Details

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

- Definition

The amount of reserve, policy claim payable and loss expense incurred by property-casualty insurance underwriter.

+ References

+ Details

Name:	us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersReservesForUnpaidClaimsAndClaimsAdjustmentExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of property-casualty insurance premium revenue not yet earned on insurance policies.

+ References

+ Details

Name:	us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersUnearnedPremiums
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant