Reporting Segments (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting Information
Life and annuity premiums and contract charges									$ 2,241	$ 2,238	$ 2,168
Net investment income									4,010	3,971	4,102
Restructuring and related charges									(34)	(44)	(30)
Net income	394	723	423	766	712	175	(624)	524	2,306	787	911
Amortization of DAC									3,884	3,971	3,807
Total income tax expense									1,000	172	189
Property-Liability
Segment Reporting Information
Underwriting income (loss)									1,200	(882)	494
Net investment income									1,326	1,201	1,189
Income tax benefit (expense) on operations									(779)	30	(426)
Realized capital gains and losses, after-tax									221	54	(207)
Gain (loss) on disposition of operations, after-tax											3
Net income									1,968	403	1,053
Amortization of DAC									3,483	3,477	3,517
Total income tax expense									893	1	314
Allstate Protection
Segment Reporting Information
Underwriting income (loss)									1,253	(857)	525
Discontinued Lines and Coverages
Segment Reporting Information
Underwriting income (loss)									(53)	(25)	(31)
Allstate Financial
Segment Reporting Information
Life and annuity premiums and contract charges									2,241	2,238	2,168
Net investment income									2,647	2,716	2,853
Periodic settlements and accruals on non-hedge derivative instruments									55	70	51
Contract benefits and interest credited to contract holder funds									(3,252)	(3,378)	(3,613)
Operating costs and expenses and amortization of deferred policy acquisition costs									(926)	(898)	(804)
Restructuring and related charges										(1)	3
Income tax benefit (expense) on operations									(236)	(240)	(214)
Operating income (loss)									529	507	444
Realized capital gains and losses, after-tax									(8)	250	(337)
Valuation changes on embedded derivatives that are not hedged, after-tax									82	(12)
DAC and DSI amortization related to realized capital gains and losses and valuation changes on embedded derivatives that are not hedged, after-tax									(42)	(108)	(29)
DAC and DSI unlocking related to realized capital gains and losses, after-tax									4	3	(12)
Reclassification of periodic settlements and accruals on non-hedge derivative instruments, after-tax									(36)	(45)	(33)
Gain (loss) on disposition of operations, after-tax									12	(5)	9
Net income									541	590	42
Amortization of DAC									401	494	290
Total income tax expense									241	289	(1)
Corporate and Other
Segment Reporting Information
Service fees									4	7	11
Net investment income									37	54	60
Operating costs and expenses									(383)	(403)	(390)
Income tax benefit (expense) on operations									136	126	128
Operating income (loss)									(206)	(216)	(191)
Realized capital gains and losses, after-tax									3	20	7
Business combination expenses, after-tax										(10)
Net income									(203)	(206)	(184)
Total income tax expense									$ (134)	$ (118)	$ (124)