Reporting Segments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting Information
Property-liability insurance premiums	$ 7,064	$ 6,770
Life and annuity premiums and contract charges	607	579
Net investment income	959	983
Realized capital gains and losses	54	131
Consolidated revenues	8,684	8,463
Property-Liability
Segment Reporting Information
Property-liability insurance premiums	7,064	6,770
Net investment income	312	341
Realized capital gains and losses	53	112
Consolidated revenues	7,429	7,223
Property-Liability | Auto
Segment Reporting Information
Property-liability insurance premiums	4,712	4,530
Property-Liability | Homeowners
Segment Reporting Information
Property-liability insurance premiums	1,697	1,616
Property-Liability | Other personal lines
Segment Reporting Information
Property-liability insurance premiums	412	404
Property-Liability | Commercial lines
Segment Reporting Information
Property-liability insurance premiums	110	114
Property-Liability | Other business lines
Segment Reporting Information
Property-liability insurance premiums	133	106
Allstate Protection
Segment Reporting Information
Property-liability insurance premiums	7,064	6,770
Allstate Financial
Segment Reporting Information
Life and annuity premiums and contract charges	607	579
Net investment income	640	635
Realized capital gains and losses	1	19
Consolidated revenues	1,248	1,233
Allstate Financial | Total life and annuity premiums
Segment Reporting Information
Life and annuity premiums and contract charges	327	303
Allstate Financial | Traditional life insurance
Segment Reporting Information
Life and annuity premiums and contract charges	127	116
Allstate Financial | Immediate annuities with life contingencies
Segment Reporting Information
Life and annuity premiums and contract charges	5	7
Allstate Financial | Accident and health insurance
Segment Reporting Information
Life and annuity premiums and contract charges	195	180
Allstate Financial | Total contract charges
Segment Reporting Information
Life and annuity premiums and contract charges	280	276
Allstate Financial | Interest-sensitive life insurance
Segment Reporting Information
Life and annuity premiums and contract charges	274	273
Allstate Financial | Fixed annuities
Segment Reporting Information
Life and annuity premiums and contract charges	6	3
Corporate and Other
Segment Reporting Information
Service fees	2	1
Net investment income	7	7
Total Corporate and Other before reclassification of service fees	9	8
Reclassification of service fees	(2)	(1)
Consolidated revenues	$ 7	$ 7