Investments (Details 6) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Other-than-temporary impairment losses by asset type
Other-than-temporary impairment losses	$ (77)	$ (47)	$ (168)	$ (100)
Included in OCI	(2)	4	8	8
Net OTTI losses recognized in earnings	(79)	(43)	(160)	(92)
Fixed income securities
Other-than-temporary impairment losses by asset type
Other-than-temporary impairment losses	(1)	(8)	(27)	(17)
Included in OCI	(2)	4	8	8
Net OTTI losses recognized in earnings	(3)	(4)	(19)	(9)
Municipal
Other-than-temporary impairment losses by asset type
Other-than-temporary impairment losses			0	(4)
Included in OCI			0	4
Net OTTI losses recognized in earnings			0	0
Corporate
Other-than-temporary impairment losses by asset type
Other-than-temporary impairment losses	(1)	(5)	(17)	(10)
Included in OCI	0	4	7	4
Net OTTI losses recognized in earnings	(1)	(1)	(10)	(6)
Asset-backed securities (“ABS”)
Other-than-temporary impairment losses by asset type
Other-than-temporary impairment losses	0	(3)	(6)	(4)
Included in OCI	(1)	0	0	1
Net OTTI losses recognized in earnings	(1)	(3)	(6)	(3)
Residential mortgage-backed securities (“RMBS”)
Other-than-temporary impairment losses by asset type
Other-than-temporary impairment losses			0	1
Included in OCI			0	(1)
Net OTTI losses recognized in earnings			0	0
Commercial mortgage-backed securities (“CMBS”)
Other-than-temporary impairment losses by asset type
Other-than-temporary impairment losses	0	0	(4)	0
Included in OCI	(1)	0	1	0
Net OTTI losses recognized in earnings	(1)	0	(3)	0
Equity securities
Other-than-temporary impairment losses by asset type
Other-than-temporary impairment losses	(51)	(36)	(128)	(75)
Included in OCI	0	0	0	0
Net OTTI losses recognized in earnings	(51)	(36)	(128)	(75)
Limited partnership interests
Other-than-temporary impairment losses by asset type
Other-than-temporary impairment losses	(24)	0	(11)	(5)
Included in OCI	0	0	0	0
Net OTTI losses recognized in earnings	(24)	0	(11)	(5)
Other
Other-than-temporary impairment losses by asset type
Other-than-temporary impairment losses	(1)	(3)	(2)	(3)
Included in OCI	0	0	0	0
Net OTTI losses recognized in earnings	$ (1)	$ (3)	$ (2)	$ (3)

No definition available.

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

- Definition

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 35
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e25351-111560

+ Details

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

- Definition

Amount before tax of other than temporary impairment loss (OTTI) on investments in available-for-sale and held-to-maturity debt securities, recognized in other comprehensive loss and attributable to parent entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 35
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e25362-111560

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 35
-Paragraph 34D
-URI http://asc.fasb.org/extlink&oid=27723805&loc=SL6284304-111560

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=66004124&loc=SL7669646-108580

+ Details

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

- Definition

The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 8B
-URI http://asc.fasb.org/extlink&oid=73527792&loc=SL6284393-111563

+ Details

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

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_FixedIncomeSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_PartnershipInterestMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_OtherThanSecuritiesInvestmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: