Business Segments (Details 2) (USD $) In Millions	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Segment Reporting Information
Life and annuity premiums and contract charges	$ 552	$ 548	$ 1,668	$ 1,637
Net investment income	994	1,005	2,996	3,104
Restructuring and related charges	8	9	28	33
Net income	165	367	64	632
Property-Liability
Segment Reporting Information
Total underwriting (loss) income	(311)	266	(1,486)	544
Net investment income	298	284	892	898
Income tax benefit (expense) on operations	38	(154)	317	(391)
Realized capital gains and losses, after-tax	15	(69)	47	(261)
Gain (loss) on disposition of operations, after-tax		4		4
Net income	40	331	(230)	794
Allstate Protection
Segment Reporting Information
Total underwriting (loss) income	(299)	287	(1,464)	571
Discontinued Lines and Coverages
Segment Reporting Information
Total underwriting (loss) income	(12)	(21)	(22)	(27)
Allstate Financial
Segment Reporting Information
Life and annuity premiums and contract charges	552	548	1,668	1,637
Net investment income	682	707	2,060	2,161
Periodic settlements and accruals on Nonhedge derivative financial instruments	18	10	54	38
Contract benefits and interest credited to contractholder funds	(850)	(891)	(2,563)	(2,731)
Operating costs and expenses and amortization of deferred policy acquisition costs	(206)	(219)	(641)	(554)
Restructuring and related charges			2	1
Income tax benefit (expense) on operations	(62)	(47)	(189)	(180)
Operating income	134	108	391	372
Realized capital gains and losses, after-tax	142	(25)	207	(360)
Valuation changes on embedded derivatives that are not hedged, after-tax	(4)		1
DAC and DSI (amortization) accretion relating to realized capital gains and losses and valuation changes on embedded derivatives that are not hedged, after-tax	(78)	7	(109)	9
DAC and DSI unlocking relating to realized capital gains and losses, After-tax			1	(18)
Reclassification of periodic settlements and accruals on non-hedge financial instruments, after-tax	(12)	(7)	(35)	(25)
Gain (loss) on disposition of operations, after-tax	1	2	(10)	4
Net income	183	85	446	(18)
Corporate and Other
Segment Reporting Information
Service fees	1	2	5	8
Net investment income	14	14	44	45
Operating costs and expenses	(117)	(97)	(310)	(301)
Income tax benefit (expense) on operations	31	31	94	96
Operating income	(71)	(50)	(167)	(152)
Realized capital gains and losses, after-tax	13	1	15	8
Net income	$ (58)	$ (49)	$ (152)	$ (144)

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The amount of deferred policy acquisition costs and sales inducement costs (amortization) accretion related to realized capital gains and losses and valuation changes on embedded derivatives that are not hedged, net of tax effect.

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The amount of deferred policy acquisition costs and sales inducement costs unlocking related to realized capital gains and losses, net of tax effect.

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The gain (loss) resulting from the sale of a disposal group that is not a discontinued operation, net of tax effect.

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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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A measure that is not based on GAAP, which is calculated as premiums earned, less claims and claims expense ("losses"), amortization of deferred policy acquisition costs ("DAC"), operating costs and expenses and restructuring and related charges, as determined using GAAP.

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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.

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Amount charged against earnings in the period for incurred and estimated costs associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, excluding asset retirement obligations.

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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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