SCHEDULE III - SUPPLEMENTARY INSURANCE INFORMATION (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Supplementary Insurance Information
Deferred policy acquisition costs	$ 3,621	$ 3,871	$ 4,180
Reserves for claims and claims expense, contract benefits and contractholder funds	75,502	77,113	81,113
Unearned premiums	10,375	10,057	9,800
Premium revenue and contract charges	28,978	28,180	28,125
Net investment income	4,010	3,971	4,102
Claims and claims expense, contract benefits and interest credited to contractholders	21,618	23,567	22,573
Amortization of deferred policy acquisition costs	3,884	3,971	3,807
Other operating costs and expenses	4,525	4,150	3,939
Premiums written (excluding life)	27,682	26,627	26,531
Allstate Protection
Supplementary Insurance Information
Deferred policy acquisition costs	1,396	1,348	1,321
Reserves for claims and claims expense, contract benefits and contractholder funds	19,036	18,042	17,046
Unearned premiums	10,345	10,023	9,761
Premium revenue and contract charges	26,737	25,942	25,955
Claims and claims expense, contract benefits and interest credited to contractholders	18,433	20,140	18,923
Amortization of deferred policy acquisition costs	3,483	3,477	3,517
Other operating costs and expenses	3,568	3,182	2,990
Premiums written (excluding life)	27,026	25,981	25,906
Discontinued Lines and Coverages
Supplementary Insurance Information
Reserves for claims and claims expense, contract benefits and contractholder funds	2,252	2,333	2,422
Premium revenue and contract charges			2
Claims and claims expense, contract benefits and interest credited to contractholders	51	21	28
Other operating costs and expenses	2	4	5
Premiums written (excluding life)	1	(1)	1
Property-Liability
Supplementary Insurance Information
Deferred policy acquisition costs	1,396	1,348	1,321
Reserves for claims and claims expense, contract benefits and contractholder funds	21,288	20,375	19,468
Unearned premiums	10,345	10,023	9,761
Premium revenue and contract charges	26,737	25,942	25,957
Net investment income	1,326	1,201	1,189
Claims and claims expense, contract benefits and interest credited to contractholders	18,484	20,161	18,951
Amortization of deferred policy acquisition costs	3,483	3,477	3,517
Other operating costs and expenses	3,570	3,186	2,995
Premiums written (excluding life)	27,027	25,980	25,907
Allstate Financial operations
Supplementary Insurance Information
Deferred policy acquisition costs	2,225	2,523	2,859
Reserves for claims and claims expense, contract benefits and contractholder funds	54,214	56,738	61,645
Unearned premiums	30	34	39
Premium revenue and contract charges	2,241	2,238	2,168
Net investment income	2,647	2,716	2,853
Claims and claims expense, contract benefits and interest credited to contractholders	3,134	3,406	3,622
Amortization of deferred policy acquisition costs	401	494	290
Other operating costs and expenses	576	556	565
Premiums written (excluding life)	655	647	624
Corporate and Other
Supplementary Insurance Information
Net investment income	37	54	60
Other operating costs and expenses	$ 379	$ 408	$ 379