Guarantees and Contingent Liabilities (Details) (USD $)	1 Months Ended	9 Months Ended
Jul. 31, 2009 claim	Sep. 30, 2011 employeeagent contract counterparties entity	Dec. 31, 2010
Proceedings:
Loss contingencies, reasonably possible pretax loss exposure in excess of the amount accrued, low estimate		$ 0
Loss contingencies, reasonably possible pretax loss exposure in excess of the amount accrued, high estimate		855,000,000
Number of former employee agents plaintiffs seek benefits for		6,500
Number of claims barred in Romero II	1
Number of claims asserted in Romero II	3
Number of remaining asserted claims in Romero II	2
Reserves for asbestos claims		1,090,000,000	1,100,000,000
Reinsurance recoverables for asbestos claims		536,000,000	555,000,000
Reserves for environmental claims		187,000,000	201,000,000
Reinsurance recoverables for environmental claims		40,000,000	47,000,000
Percentage of net asbestos and environmental reserves that were for incurred but not reported estimated losses (as a percent)		60.00%	60.00%
Guarantee on fixed income securities
Guarantees:
Maximum amount at risk pursuant to a guarantee		57,000,000
Residual guarantee
Guarantees:
Maximum amount at risk pursuant to a guarantee		$ 7,000,000
Guarantee obligations term, low end of range (in years)		1
Guarantee obligations term, high end of range (in years)		3

Name:	all_ContingentLiabilitiesAbstract
Namespace Prefix:	all
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The high end of the range of the approximate term of the guarantee or each group of similar guarantees.

+ Details

Name:	all_GuaranteeObligationsTermHighEndOfRange
Namespace Prefix:	all
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The low end of the range of the approximate term of the guarantee or each group of similar guarantees.

+ Details

Name:	all_GuaranteeObligationsTermLowEndOfRange
Namespace Prefix:	all
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date of reserves for the costs of settling insured claims and costs incurred in the claims settlement process attributable to asbestos, net of estimated reinsurance recoveries.

+ Details

Name:	all_LiabilityForAsbestosClaimsNet
Namespace Prefix:	all
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of reserves for the costs of settling insured claims and costs incurred in the claims settlement process attributable to environmental claims, net of estimated reinsurance recoveries.

+ Details

Name:	all_LiabilityForEnvironmentalClaimsNet
Namespace Prefix:	all
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the number of claims asserted by plaintiffs in a worker classification issue.

+ Details

Name:	all_NumberOfClaimsAssertedInWorkerClassificationIssue
Namespace Prefix:	all
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of claims barred by the release and waiver in a worker classification issue.

+ Details

Name:	all_NumberOfClaimsBarredInWorkerClassificationIssue
Namespace Prefix:	all
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the amount of former employee agents plaintiffs seek benefits for.

+ Details

Name:	all_NumberOfFormerEmployeeAgentsPlaintiffsSeekBenefitsFor
Namespace Prefix:	all
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of claims which are not yet barred by the release and waiver in a worker classification issue.

+ Details

Name:	all_NumberOfRemainingAssertedClaimsInWorkerClassificationIssue
Namespace Prefix:	all
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The percentage of net asbestos and environment reserves that were for incurred but not reported estimated losses.

+ Details

Name:	all_PercentageOfAsbestosAndEnvironmentReservesIncurredButNotReportedEstimatedLosses
Namespace Prefix:	all
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The known and estimated amount recoverable related to asbestos claims as of the balance sheet date from reinsurers for claims paid or incurred by the ceding insurer and associated claims settlement expenses, including estimated amounts for claims incurred but not reported, and policy benefits, net of any related valuation allowance.

+ Details

Name:	all_ReinsuranceRecoverablesAsbestos
Namespace Prefix:	all
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The known and estimated amount recoverable related to environment related claims as of the balance sheet date from reinsurers for claims paid or incurred by the ceding insurer and associated claims settlement expenses, including estimated amounts for claims incurred but not reported, and policy benefits, net of any related valuation allowance.

+ Details

Name:	all_ReinsuranceRecoverablesEnvironment
Namespace Prefix:	all
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.

+ Details

Name:	us-gaap_GuaranteeObligationsLineItems
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

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

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 45

-Paragraph 13

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)(1)

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

+ Details

Name:	us-gaap_GuaranteeObligationsMaximumExposure
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The estimated maximum amount of possible loss from the contingency.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 9

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14557-108349

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

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 14

-Paragraph 3

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9, 10, 11, 12

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14435-108349

+ Details

Name:	us-gaap_LossContingencyRangeOfPossibleLossMaximum
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The estimated minimum amount of possible loss from the contingency.

+ References

+ Details

Name:	us-gaap_LossContingencyRangeOfPossibleLossMinimum
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant