Business Segments (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting Information
Life and annuity premiums and contract charges	$ 584	$ 563	$ 1,742	$ 1,675
Net investment income	950	940	2,917	2,977
Restructuring and related charges	(13)	(9)	(59)	(25)
Net income available to common shareholders	310	723	1,453	1,912
Property-Liability
Segment Reporting Information
Underwriting income (loss)	697	659	1,424	1,316
Net investment income	309	299	993	964
Income tax expense on operations	(333)	(308)	(780)	(717)
Realized capital gains and losses, after-tax	(17)	(11)	253	125
(Loss) gain on disposition of operations, after-tax			(1)
Net income available to common shareholders	656	639	1,889	1,688
Allstate Protection
Segment Reporting Information
Underwriting income (loss)	831	701	1,566	1,365
Discontinued Lines and Coverages
Segment Reporting Information
Underwriting income (loss)	(134)	(42)	(142)	(49)
Allstate Financial
Segment Reporting Information
Life and annuity premiums and contract charges	584	563	1,742	1,675
Net investment income	633	632	1,901	1,982
Periodic settlements and accruals on non-hedge derivative instruments	2	15	17	45
Contract benefits and interest credited to contract holder funds	(800)	(810)	(2,380)	(2,441)
Operating costs and expenses and amortization of deferred policy acquisition costs	(241)	(264)	(670)	(703)
Restructuring and related charges	(4)		(7)
Income tax expense on operations	(47)	(39)	(175)	(173)
Operating income (loss)	127	97	428	385
Realized capital gains and losses, after-tax	(12)	(36)	37	(45)
Valuation changes on embedded derivatives that are not hedged, after-tax	(10)	97	(13)	88
DAC and DSI accretion (amortization) related to realized capital gains and losses and valuation changes on embedded derivatives that are not hedged, after-tax	1	(28)	(2)	(38)
DAC and DSI unlocking related to realized capital gains and losses, after-tax	7	4	7	4
Reclassification of periodic settlements and accruals on non-hedge derivative instruments, after-tax	(1)	(9)	(11)	(29)
(Loss) gain on disposition of operations, after-tax	(472)	6	(470)	10
Net income available to common shareholders	(360)	131	(24)	375
Corporate and Other
Segment Reporting Information
Service fees	3	1	6	3
Net investment income	8	9	23	31
Operating costs and expenses	(162)	(91)	(366)	(286)
Income tax expense on operations	58	34	130	101
Preferred stock dividends	(6)		(6)
Operating income (loss)	(99)	(47)	(213)	(151)
Realized capital gains and losses, after-tax	1		1
Loss on extinguishment of debt, after-tax	(6)		(318)
Postretirement benefits curtailment gain, after-tax	118		118
Net income available to common shareholders	$ 14	$ (47)	$ (412)	$ (151)