Business Segments (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment Reporting Information
Life and annuity premiums and contract charges	$ 579	$ 559	$ 1,158	$ 1,112
Net investment income	984	1,026	1,967	2,037
Restructuring and related charges	(20)	(10)	(46)	(16)
Net income	434	423	1,143	1,189
Property-Liability
Segment Reporting Information
Underwriting income (loss)	269	134	727	657
Net investment income	343	352	684	665
Income tax benefit (expense) on operations	(191)	(144)	(447)	(409)
Realized capital gains and losses, after-tax	197	12	270	136
Gain (loss) on disposition of operations, after-tax	(1)		(1)
Net income	617	354	1,233	1,049
Allstate Protection
Segment Reporting Information
Underwriting income (loss)	273	138	735	664
Discontinued Lines and Coverages
Segment Reporting Information
Underwriting income (loss)	(4)	(4)	(8)	(7)
Allstate Financial
Segment Reporting Information
Life and annuity premiums and contract charges	579	559	1,158	1,112
Net investment income	633	663	1,268	1,350
Periodic settlements and accruals on non-hedge derivative instruments	5	15	15	30
Contract benefits and interest credited to contract holder funds	(786)	(824)	(1,580)	(1,631)
Operating costs and expenses and amortization of deferred policy acquisition costs	(205)	(211)	(429)	(439)
Restructuring and related charges	(1)		(3)
Income tax benefit (expense) on operations	(68)	(64)	(128)	(134)
Operating income (loss)	157	138	301	288
Realized capital gains and losses, after-tax	37	5	49	(9)
Valuation changes on embedded derivatives that are not hedged, after-tax	3	(3)	(3)	(9)
DAC and DSI amortization related to realized capital gains and losses and valuation changes on embedded derivatives that are not hedged, after-tax	(4)		(3)	(10)
Reclassification of periodic settlements and accruals on non-hedge derivative instruments, after-tax	(4)	(10)	(10)	(20)
Gain (loss) on disposition of operations, after-tax	1	2	2	4
Net income	190	132	336	244
Corporate and Other
Segment Reporting Information
Service fees	2	1	3	2
Net investment income	8	11	15	22
Operating costs and expenses	(108)	(108)	(204)	(195)
Income tax benefit (expense) on operations	37	33	72	67
Preferred stock dividends
Operating income (loss)	(61)	(63)	(114)	(104)
Loss on extinguishment of debt, after-tax	(312)		(312)
Net income	$ (373)	$ (63)	$ (426)	$ (104)