SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities
Net income (loss)	$ 394	$ 723	$ 423	$ 766	$ 712	$ 175	$ (624)	$ 524	$ 2,306	$ 787	$ 911
Adjustments to reconcile net income to net cash provided by operating activities:
Net cash provided by operating activities									3,054	1,929	3,689
Cash flows from investing activities
Change in short-term investments, net									(698)	2,182	(382)
Acquisition of subsidiary, net									(1,524)	(1,696)	(1,342)
Net cash provided by investing activities									1,581	6,161	2,332
Cash flows from financing activities
Proceeds from issuance of long-term debt									493	7
Repayment of long-term debt									(352)	(7)	(2)
Dividends paid to shareholders									(534)	(435)	(430)
Treasury stock purchases									(913)	(953)	(152)
Shares reissued under equity incentive plans, net									85	19	28
Excess tax benefits on share-based payment arrangements									10	(5)	(7)
Other									(33)	2	(18)
Net cash used in financing activities									(4,605)	(7,876)	(6,071)
Net increase (decrease) in cash									30	214	(50)
Cash at beginning of year				776				562	776	562	612
Cash at end of year	806				776				806	776	562
Supplemental disclosures of non-cash investing activity and cash flow information
Non-cash decrease in investment in subsidiaries									323	601	664
Interest paid on debt									366	363	363
Allstate Corporation
Cash flows from operating activities
Net income (loss)									2,306	787	911
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in net (income) loss of subsidiaries									(2,547)	(1,027)	(1,139)
Dividends received from subsidiaries									1,038	878	1,384
Realized capital gains and losses										(28)	1
Change in other operating assets and liabilities									55	77	102
Net cash provided by operating activities									852	687	1,259
Cash flows from investing activities
Proceeds from sales of investments									92	1,045	217
Investment purchases										(653)	(219)
Investment collections									100
Return of capital from subsidiaries									154	27
Change in short-term investments, net									15	1,282	(696)
Acquisition of subsidiary, net										(1,009)
Net cash provided by investing activities									361	692	(698)
Cash flows from financing activities
Proceeds from issuance of long-term debt									493
Repayment of long-term debt									(352)
Dividends paid to shareholders									(534)	(435)	(430)
Treasury stock purchases									(913)	(953)	(152)
Shares reissued under equity incentive plans, net									85	19	28
Excess tax benefits on share-based payment arrangements									10	(5)	(7)
Other									(3)
Net cash used in financing activities									(1,214)	(1,374)	(561)
Net increase (decrease) in cash									(1)	5
Cash at beginning of year				5					5
Cash at end of year	4				5				4	5
Supplemental disclosures of non-cash investing activity and cash flow information
Non-cash decrease in investment in subsidiaries										713
Interest paid on debt									$ 364	$ 360	$ 360