SCHEDULE II - CONDENSED FINANCIAL INFORMATION OF REGISTRANT (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities
Net income	$ 2,171	$ 2,850	$ 2,280
Adjustments to reconcile net income to net cash provided by operating activities:
Loss on extinguishment of debt	0	1	491
Changes in:
Net cash provided by operating activities	3,616	3,236	4,242
Cash flows from investing activities
Change in short-term investments, net	385	272	(427)
Net cash provided by investing activities	$ 742	1,621	1,580
Cash flows from financing activities
Proceeds from issuance of long-term debt		0	2,271
Repayments of long-term debt	$ (20)	(1,006)	(2,627)
Proceeds from issuance of preferred stock	0	965	781
Dividends paid on common stock	(483)	(477)	(352)
Dividends paid on preferred stock	(116)	(87)	(6)
Treasury stock purchases	(2,808)	(2,301)	(1,834)
Shares reissued under equity incentive plans, net	130	266	170
Excess tax benefits on share-based payment arrangements	45	41	38
Other	7	(14)	(12)
Net cash used in financing activities	(4,520)	(4,875)	(5,953)
Net decrease in cash	(162)	(18)	(131)
Cash at beginning of year	657	675	806
Cash at end of year	495	657	675
Supplemental disclosures of non-cash investing activity and cash flow information
Interest paid on debt	289	332	361
Allstate Corporation
Cash flows from operating activities
Net income	2,171	2,850	2,280
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in net income of subsidiaries	(2,300)	(3,039)	(2,687)
Dividends received from subsidiaries	2,300	2,497	1,992
Loss on extinguishment of debt	0	1	491
Changes in:
Pension and other postretirement benefits	(15)	41	(184)
Income taxes	77	(158)	113
Operating assets and liabilities	26	(29)	25
Net cash provided by operating activities	2,259	2,163	2,030
Cash flows from investing activities
Proceeds from sales of investments	399	351	0
Investment purchases	(4)	(1,174)	(156)
Investment collections	0	155	200
Return of capital from subsidiaries	50	1,200	37
Change in short-term investments, net	397	(88)	(450)
Net cash provided by investing activities	842	444	(369)
Cash flows from financing activities
Proceeds from issuance of long-term debt	0	0	2,271
Repayments of long-term debt	(20)	(962)	(2,627)
Proceeds from issuance of preferred stock	0	965	781
Dividends paid on common stock	(483)	(477)	(352)
Dividends paid on preferred stock	(116)	(87)	(6)
Treasury stock purchases	(2,808)	(2,301)	(1,834)
Shares reissued under equity incentive plans, net	130	266	170
Excess tax benefits on share-based payment arrangements	45	41	38
Other	0	(2)	(1)
Net cash used in financing activities	(3,252)	(2,557)	(1,560)
Net decrease in cash	(151)	50	101
Cash at beginning of year	155	105	4
Cash at end of year	4	155	105
Supplemental disclosures of non-cash investing activity and cash flow information
Interest paid on debt	$ 289	$ 332	$ 359