SCHEDULE III - SUPPLEMENTARY INSURANCE INFORMATION (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplementary Insurance Information
Deferred policy acquisition costs	$ 3,861	$ 3,525	$ 3,372
Reserves for claims and claims expense, contract benefits and contractholder funds	57,411	57,832	58,547
Unearned premiums	12,202	11,655	10,932
Premium revenue and contract charges	32,467	31,086	29,970
Net investment income	3,156	3,459	3,943
Claims and claims expense, contract benefits and interest credited to contractholders	23,598	22,112	21,106
Amortization of deferred policy acquisition costs	4,364	4,135	4,002
Other operating costs and expenses	4,412	4,682	5,315
Premiums written (excluding life)	31,648	30,360	28,887
Allstate Protection
Supplementary Insurance Information
Deferred policy acquisition costs	2,029	1,820	1,625
Reserves for claims and claims expense, contract benefits and contractholder funds	21,807	20,709	19,598
Unearned premiums	12,189	11,640	10,917
Premium revenue and contract charges	30,309	28,928	27,618
Claims and claims expense, contract benefits and interest credited to contractholders	20,981	19,315	17,769
Amortization of deferred policy acquisition costs	4,102	3,875	3,674
Other operating costs and expenses	3,612	3,851	3,814
Premiums written (excluding life)	30,871	29,613	28,164
Discontinued Lines and Coverages
Supplementary Insurance Information
Deferred policy acquisition costs	0	0	0
Reserves for claims and claims expense, contract benefits and contractholder funds	2,062	2,214	2,259
Unearned premiums	0	0	0
Premium revenue and contract charges	0	1	0
Claims and claims expense, contract benefits and interest credited to contractholders	53	113	142
Amortization of deferred policy acquisition costs	0	0	0
Other operating costs and expenses	2	3	1
Premiums written (excluding life)	0	1	0
Property-Liability
Supplementary Insurance Information
Deferred policy acquisition costs	2,029	1,820	1,625
Reserves for claims and claims expense, contract benefits and contractholder funds	23,869	22,923	21,857
Unearned premiums	12,189	11,640	10,917
Premium revenue and contract charges	30,309	28,929	27,618
Net investment income	1,237	1,301	1,375
Claims and claims expense, contract benefits and interest credited to contractholders	21,034	19,428	17,911
Amortization of deferred policy acquisition costs	4,102	3,875	3,674
Other operating costs and expenses	3,614	3,854	3,815
Premiums written (excluding life)	30,871	29,614	28,164
Allstate Financial operations
Supplementary Insurance Information
Deferred policy acquisition costs	1,832	1,705	1,747
Reserves for claims and claims expense, contract benefits and contractholder funds	33,542	34,909	36,690
Unearned premiums	13	15	15
Premium revenue and contract charges	2,158	2,157	2,352
Net investment income	1,884	2,131	2,538
Claims and claims expense, contract benefits and interest credited to contractholders	2,564	2,684	3,195
Amortization of deferred policy acquisition costs	262	260	328
Other operating costs and expenses	472	468	572
Premiums written (excluding life)	777	746	723
Corporate and Other
Supplementary Insurance Information
Deferred policy acquisition costs	0	0	0
Reserves for claims and claims expense, contract benefits and contractholder funds	0	0	0
Unearned premiums	0	0	0
Premium revenue and contract charges	0	0	0
Net investment income	35	27	30
Claims and claims expense, contract benefits and interest credited to contractholders	0	0	0
Amortization of deferred policy acquisition costs	0	0	0
Other operating costs and expenses	326	360	928
Premiums written (excluding life)	$ 0	$ 0	$ 0