SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenues
Investment income, less investment expense									$ 3,971	$ 4,102	$ 4,444
Realized capital gains and losses									503	(827)	(583)
Total revenues	8,236	8,242	8,081	8,095	8,087	7,908	7,656	7,749	32,654	31,400	32,013
Costs and expenses
Interest expense									367	367	392
Other operating expenses									3,468	3,281	3,007
Total costs and expenses									31,679	30,285	30,772
Income tax benefit									(172)	(198)	(394)
Net income	724	165	(620)	519	296	367	145	120	788	928	854
Other comprehensive income (loss), after-tax
Unrealized net capital gains and losses									428	1,785	3,446
Unrealized foreign currency translation adjustments									(12)	23	41
Unrecognized pension and other postretirement benefit cost									(239)	94	(214)
Other comprehensive income, after-tax									177	1,902	3,273
Comprehensive income									965	2,830	4,127
Allstate Corporation
Revenues
Investment income, less investment expense									16	14	10
Realized capital gains and losses									28	(1)	1
Other income									9	11	21
Total revenues									53	24	32
Costs and expenses
Interest expense									365	365	389
Other operating expenses									63	22	18
Total costs and expenses									428	387	407
Loss from operations before income tax benefit and equity in net income (loss) of subsidiaries									(375)	(363)	(375)
Income tax benefit									(135)	(135)	(144)
Loss before equity in net income (loss) of subsidiaries									(240)	(228)	(231)
Equity in net income (loss) of subsidiaries									1,028	1,156	1,085
Net income									788	928	854
Other comprehensive income (loss), after-tax
Unrealized net capital gains and losses									428	1,785	3,446
Unrealized foreign currency translation adjustments									(12)	23	41
Unrecognized pension and other postretirement benefit cost									(239)	94	(214)
Other comprehensive income, after-tax									177	1,902	3,273
Comprehensive income									$ 965	$ 2,830	$ 4,127