Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related Party Transactions
Allocation of operating expenses	$ 339	$ 456	$ 451
Premium revenue	589us-gaap_PremiumsEarnedNet	613us-gaap_PremiumsEarnedNet	593us-gaap_PremiumsEarnedNet
Reserves recorded for annuities	11,566	11,589
Reinsurance recoverable from related parties	2,586us-gaap_ReinsuranceRecoverables	2,754us-gaap_ReinsuranceRecoverables
Structured settlement annuities with life contingencies
Related Party Transactions
Reserves recorded for annuities	6,682	6,645
Allstate Financial Services, LLC
Related Party Transactions
Commission and other distribution expenses	4	13	11
AIC \| Structured settlement annuities
Related Party Transactions
Annuities issued		7	35
Reserves recorded for annuities	4,680	4,720
AIC \| Structured settlement annuities with life contingencies
Related Party Transactions
Premium revenue		4	3
Lincoln Benefit Life Company \| LB Re
Related Party Transactions
Reinsurance recoverable from related parties	2
Reinsurance payables to affiliates	3
Loss on the transaction	$ (1)

Represents information pertaining annuities issued during the period.

No definition available.

Name:	all_AnnuitiesIssued
Namespace Prefix:	all_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the amount of fees and commissions earned from providing services such as leasing of space or maintaining: (1) depositor accounts; (2) transfer agent; (3) fiduciary and trust; (4) brokerage and underwriting; (5) mortgage; (6) credit cards; (7) correspondent clearing; and (8) other such services and activities performed for others.

+ References

No definition available.

+ Details

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

- Definition

Gain or loss on transaction between entities under common control recorded directly to equity.

+ References

No definition available.

+ Details

Name:	all_GainLossOnTransactionBetweenEntitiesUnderCommonControl
Namespace Prefix:	all_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of accrued obligation to policyholders that relates to insured events for long-duration contracts.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 40

-Section 25

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=28366191&loc=d3e13145-158430

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 13

-Subparagraph a

-Article 7

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 210.7-03.13(a)(1))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

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

- Definition

Amount, after premiums ceded to other entities and premiums assumed by the entity, of premiums earned.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 17

-Article 12

Reference 2: 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

Reference 3: 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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 1

-Article 7

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 605

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.13(c))

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

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

- Definition

The carrying amount as of the balance sheet date of the known and estimated amounts owed to insurers under reinsurance treaties or other arrangements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.13(a)(3),(c))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 13

-Subparagraph a(3)

-Article 7

+ Details

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

- Definition

Amount after valuation allowance recoverable 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://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 6

-Article 7

Reference 2: 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 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

+ Details

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

- Definition

Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 850

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

+ Details

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

- Details

Name:	us-gaap_RelatedPartyTransactionLineItems
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
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- Details

Name:	dei_LegalEntityAxis=us-gaap_ParentCompanyMember
Namespace Prefix:
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- Details

Name:	us-gaap_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentAxis=all_StructuredSettlementLifeContingenciesAnnuitiesMember
Namespace Prefix:
Data Type:	na
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Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=all_AllstateFinancialServicesLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: