Derivative Financial Instruments and Off-balance sheet Financial Instruments (Details 4) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014 counterparties	Dec. 31, 2013 counterparties
Derivative Financial Instruments and Off-balance sheet Financial Instruments
Cash and securities pledged as collateral by counterparties	$ 4
Securities pledged as collateral to counterparties	25
Collateral posted under MNAs, credit-risk-contingent provisions in a liability position	7	14
Collateral posted under MNAs for contracts without credit-risk-contingent liabilities	18
Credit Derivatives
Number of counter-parties	7all_NumberOfCounterparties	9all_NumberOfCounterparties
Notional amount	353	1,783
Credit exposure	5all_CounterpartyCreditExposure	15all_CounterpartyCreditExposure
Exposure, net of collateral	3	3
Gross liability fair value of contracts containing credit-risk-contingent features	16	28
Gross asset fair value of contracts containing credit-risk-contingent features and subject to MNAs	(4)	(11)
Collateral posted under MNAs for contracts containing credit-risk-contingent features	(7)	(14)
Maximum amount of additional exposure for contracts with credit-risk-contingent features if all features were triggered concurrently	5	3
A+
Credit Derivatives
Number of counter-parties	1	1
Notional amount	164	22
Credit exposure	2	1
Exposure, net of collateral	1	1
A
Credit Derivatives
Number of counter-parties	3	5
Notional amount	118	1,628
Credit exposure	3	9
Exposure, net of collateral	2	2
A-
Credit Derivatives
Number of counter-parties	1	1
Notional amount	8	24
Credit exposure		1
BBB+
Credit Derivatives
Number of counter-parties	1	1
Notional amount	11	33
Credit exposure		3
BBB
Credit Derivatives
Number of counter-parties	1	1
Notional amount	52	76
Credit exposure		$ 1

This element represents cash and securities pledged as collateral from counterparties.

No definition available.

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

- Definition

The amount of credit exposure by counterparties related to derivative contracts.

+ References

No definition available.

+ Details

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

- Definition

The amount of credit exposure by counterparties net of collateral received, related to derivative contracts.

+ References

No definition available.

+ Details

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

- Details

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

- Definition

Fair value of derivative asset, presented on a gross basis containing credit risk contingent features and which is subject to master netting arrangements.

+ References

No definition available.

+ Details

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

- Definition

Fair value of derivative liabilities, presented on a gross basis containing credit risk contingent features.

+ References

No definition available.

+ Details

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

- Definition

The notional amount of derivative contracts for which the entity has counterparty credit exposure.

+ References

No definition available.

+ Details

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

- Definition

The number of counterparties to which the entity has counterparty credit exposure related to derivative contracts.

+ References

No definition available.

+ Details

Name:	all_NumberOfCounterparties
Namespace Prefix:	all_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

This element represents securities pledged to counterparties as collateral for credit exposure.

+ References

No definition available.

+ Details

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

- Definition

This element represents the securities given to counterparties as collateral for credit exposure without credit risk contingent provisions.

+ References

No definition available.

+ Details

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

- Definition

The aggregate fair value of additional assets that would be required to be posted as collateral for derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4H

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624258-113959

+ Details

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

- Definition

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4H

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624258-113959

+ Details

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

- Details

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

- Details

Name:	us-gaap_CreditRatingStandardPoorsAxis=us-gaap_StandardPoorsAMinusRatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_CreditRatingStandardPoorsAxis=us-gaap_StandardPoorsAPlusRatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_CreditRatingStandardPoorsAxis=us-gaap_StandardPoorsARatingMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_CreditRatingStandardPoorsAxis=us-gaap_StandardPoorsBBBPlusRatingMember
Namespace Prefix:
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- Details

Name:	us-gaap_CreditRatingStandardPoorsAxis=us-gaap_StandardPoorsBBBRatingMember
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