Reporting Segments (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information
Property-liability insurance premiums									$ 27,618	$ 26,737	$ 25,942
Life and annuity premiums and contract charges									2,352	2,241	2,238
Net investment income									3,943	4,010	3,971
Realized capital gains and losses									594	327	503
Consolidated revenues	8,792	8,465	8,787	8,463	8,547	8,128	8,278	8,362	34,507	33,315	32,654
Property-Liability
Segment Reporting Information
Property-liability insurance premiums									27,618	26,737	25,942
Net investment income									1,375	1,326	1,201
Realized capital gains and losses									519	335	85
Consolidated revenues									29,512	28,398	27,228
Property-Liability | Auto
Segment Reporting Information
Property-liability insurance premiums									18,449	17,928	17,299
Property-Liability | Homeowners
Segment Reporting Information
Property-liability insurance premiums									6,613	6,359	6,200
Property-Liability | Other personal lines
Segment Reporting Information
Property-liability insurance premiums									1,629	1,594	1,566
Property-Liability | Commercial lines
Segment Reporting Information
Property-liability insurance premiums									456	462	495
Property-Liability | Other business lines
Segment Reporting Information
Property-liability insurance premiums									471	394	382
Allstate Protection
Segment Reporting Information
Property-liability insurance premiums										26,737	25,942
Allstate Financial
Segment Reporting Information
Life and annuity premiums and contract charges									2,352	2,241	2,238
Net investment income									2,538	2,647	2,716
Realized capital gains and losses									74	(13)	388
Consolidated revenues									4,964	4,875	5,342
Allstate Financial | Total life and annuity premiums
Segment Reporting Information
Life and annuity premiums and contract charges									1,248	1,168	1,190
Allstate Financial | Traditional life insurance
Segment Reporting Information
Life and annuity premiums and contract charges									491	470	441
Allstate Financial | Immediate annuities with life contingencies
Segment Reporting Information
Life and annuity premiums and contract charges									37	45	106
Allstate Financial | Accident and health insurance:
Segment Reporting Information
Life and annuity premiums and contract charges									720	653	643
Allstate Financial | Total contract charges
Segment Reporting Information
Life and annuity premiums and contract charges									1,104	1,073	1,048
Allstate Financial | Interest-sensitive life insurance
Segment Reporting Information
Life and annuity premiums and contract charges									1,086	1,055	1,015
Allstate Financial | Fixed annuities
Segment Reporting Information
Life and annuity premiums and contract charges									18	18	33
Corporate and Other
Segment Reporting Information
Service fees									9	4	7
Net investment income									30	37	54
Realized capital gains and losses									1	5	30
Total Corporate and Other before reclassification of service fees									40	46	91
Reclassification of service fees									(9)	(4)	(7)
Consolidated revenues									$ 31	$ 42	$ 84