SCHEDULE III - SUPPLEMENTARY INSURANCE INFORMATION (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplementary Insurance Information
Deferred policy acquisition costs	$ 3,525	$ 3,372	$ 3,621
Reserves for claims and claims expense, contract benefits and contractholder funds	57,832	58,547	75,502
Unearned premiums	11,655	10,932	10,375
Premium revenue and contract charges	31,086	29,970	28,978
Net investment income	3,459	3,943	4,010
Claims and claims expense, contract benefits and interest credited to contractholders	22,112	21,106	21,618
Amortization of deferred policy acquisition costs	4,135	4,002	3,884
Other operating costs and expenses	4,682	5,315	4,525
Premiums written (excluding life)	30,360	28,887	27,682
Allstate Protection
Supplementary Insurance Information
Deferred policy acquisition costs	1,820	1,625	1,396
Reserves for claims and claims expense, contract benefits and contractholder funds	20,709	19,598	19,036
Unearned premiums	11,640	10,917	10,345
Premium revenue and contract charges	28,928	27,618	26,737
Claims and claims expense, contract benefits and interest credited to contractholders	19,315	17,769	18,433
Amortization of deferred policy acquisition costs	3,875	3,674	3,483
Other operating costs and expenses	3,851	3,814	3,568
Premiums written (excluding life)	29,613	28,164	27,026
Discontinued Lines and Coverages
Supplementary Insurance Information
Reserves for claims and claims expense, contract benefits and contractholder funds	2,214	2,259	2,252
Premium revenue and contract charges	1
Claims and claims expense, contract benefits and interest credited to contractholders	113	142	51
Other operating costs and expenses	3	1	2
Premiums written (excluding life)	1		1
Property-Liability
Supplementary Insurance Information
Deferred policy acquisition costs	1,820	1,625	1,396
Reserves for claims and claims expense, contract benefits and contractholder funds	22,923	21,857	21,288
Unearned premiums	11,640	10,917	10,345
Premium revenue and contract charges	28,929	27,618	26,737
Net investment income	1,301	1,375	1,326
Claims and claims expense, contract benefits and interest credited to contractholders	19,428	17,911	18,484
Amortization of deferred policy acquisition costs	3,875	3,674	3,483
Other operating costs and expenses	3,854	3,815	3,570
Premiums written (excluding life)	29,614	28,164	27,027
Allstate Financial operations
Supplementary Insurance Information
Deferred policy acquisition costs	1,705	1,747	2,225
Reserves for claims and claims expense, contract benefits and contractholder funds	34,909	36,690	54,214
Unearned premiums	15	15	30
Premium revenue and contract charges	2,157	2,352	2,241
Net investment income	2,131	2,538	2,647
Claims and claims expense, contract benefits and interest credited to contractholders	2,684	3,195	3,134
Amortization of deferred policy acquisition costs	260	328	401
Other operating costs and expenses	468	572	576
Premiums written (excluding life)	746	723	655
Corporate and Other
Supplementary Insurance Information
Net investment income	27	30	37
Other operating costs and expenses	$ 360	$ 928	$ 379