Business Segments (Details) (USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Segment Reporting Information
Property-liability insurance premiums	$ 6,457	$ 6,513	$ 12,905	$ 13,016
Life and annuity premiums and contract charges	547	545	1,116	1,089
Net investment income	1,020	1,049	2,002	2,099
Realized capital gains and losses	57	(451)	153	(799)
Consolidated revenues	8,081	7,656	16,176	15,405
Property-Liability
Segment Reporting Information
Net investment income	310	310	594	614
Realized capital gains and losses	(8)	(106)	49	(296)
Consolidated revenues	6,759	6,717	13,548	13,334
Property-Liability \| Total auto
Segment Reporting Information
Property-liability insurance premiums	4,299	4,384	8,598	8,755
Property-Liability \| Standard auto
Segment Reporting Information
Property-liability insurance premiums	4,093	4,154	8,181	8,291
Property-Liability \| Non-standard auto
Segment Reporting Information
Property-liability insurance premiums	206	230	417	464
Property-Liability \| Homeowners
Segment Reporting Information
Property-liability insurance premiums	1,548	1,512	3,087	3,028
Property-Liability \| Other personal lines
Segment Reporting Information
Property-liability insurance premiums	610	617	1,221	1,233
Allstate Protection
Segment Reporting Information
Property-liability insurance premiums	6,457	6,513	12,906	13,016
Discontinued Lines and Coverages
Segment Reporting Information
Property-liability insurance premiums			(1)
Allstate Financial
Segment Reporting Information
Life and annuity premiums and contract charges	547	545	1,116	1,089
Net investment income	694	723	1,378	1,454
Realized capital gains and losses	62	(353)	101	(515)
Consolidated revenues	1,303	915	2,595	2,028
Allstate Financial \| Total life and annuity premiums
Segment Reporting Information
Life and annuity premiums and contract charges	286	286	598	575
Allstate Financial \| Traditional life insurance
Segment Reporting Information
Life and annuity premiums and contract charges	109	104	217	210
Allstate Financial \| Immediate annuities with life contingencies
Segment Reporting Information
Life and annuity premiums and contract charges	15	31	58	58
Allstate Financial \| Accident and health insurance:
Segment Reporting Information
Life and annuity premiums and contract charges	162	151	323	307
Allstate Financial \| Total contract charges
Segment Reporting Information
Life and annuity premiums and contract charges	261	259	518	514
Allstate Financial \| Interest-sensitive life insurance
Segment Reporting Information
Life and annuity premiums and contract charges	253	249	501	491
Allstate Financial \| Fixed annuities
Segment Reporting Information
Life and annuity premiums and contract charges	8	10	17	23
Corporate and Other
Segment Reporting Information
Service fees	2	3	4	6
Net investment income	16	16	30	31
Realized capital gains and losses	3	8	3	12
Total Corporate and Other before reclassification of service fees	21	27	37	49
Reclassification of service fees	(2)	(3)	(4)	(6)
Consolidated revenues	$ 19	$ 24	$ 33	$ 43

Premiums recognized as revenue in the period on all life insurance and reinsurance contracts, as well as accident and health insurance and reinsurance contracts, after subtracting any amounts ceded to another insurer. Also includes an amount that an insurer adds to a policy's premium, or deducts from a policy's cash value or contract holder's account, as compensation for services rendered (may include fees), after subtracting any amounts ceded to another insurer.

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- Definition

Represents the reclassification of service fees.

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Represents the revenue before reclassification of service fees.

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- Definition

Total 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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher OTS
-Name Federal Regulation (FR)
-Number Title 12
-Chapter V
-Section 563c.102
-Paragraph 13
-Subsection II

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 13
-Article 9

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The income earned from investments in securities and property, equipment and other capital assets. It includes rent from property and equipment, dividends from shares in corporations, and interest from bonds, loans, mortgages, derivatives, commercial paper, bank accounts, certificates of deposits, treasuries, and other financial securities. It does not include realized gains and losses on investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 16
-Article 12

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 2
-Article 7

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Premiums recognized as revenue in the period earned on all property and casualty insurance and reinsurance contracts after subtracting any amounts ceded to another insurer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 113
-Paragraph 27

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 1
-Article 7

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 18
-Article 12

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- Definition

The net realized gains or losses on investments during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Paragraph 3
-Subparagraph a
-Article 7

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Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 03
-Paragraph 1
-Article 5

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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.

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