Condensed Consolidated Statements of Shareholders’ Equity (unaudited) - USD ($) $ in Millions	Total	Preferred stock par value	Preferred stock additional capital paid-in	Common stock par value	Common stock additional capital paid-in	Retained income	Treasury stock	Accumulated other comprehensive income (loss)	Noncontrolling interest
Increase (decrease) in equity
Total equity			$ 1,970		$ 3,788	$ 50,970	$ (36,857)	$ (2,392)	$ (125)
Balance, beginning of period at Dec. 31, 2022			1,970		3,788	50,970	(36,857)	(2,392)	(125)
Increase (decrease) in equity
Preferred stock issuance, net of issuance costs			587
Preferred stock redemption			(556)
Equity incentive plans activity, net					(2)
Net income (loss)	$ (1,696)					(1,672)			(24)
Dividends on common stock (declared per share of $0.92, $0.89, $1.84, and $1.78 )						(469)
Dividends on preferred stock						(63)
Shares acquired							(307)
Shares reissued under equity incentive plans, net							33
Change in unrealized net capital gains and losses	410							410	4
Change in unrealized foreign currency translation adjustments	78							78
Change in unamortized pension and other postretirement prior service credit	(9)							(9)
Change in discount rate for reserve for future policy benefits	(1)							(1)
Capital transaction for noncontrolling interest									0
Balance, end of period at Jun. 30, 2023	15,372	$ 0	2,001	$ 9	3,786	48,766	(37,131)	(1,914)	(145)
Increase (decrease) in equity
Total equity			1,970		3,780	50,388	(36,980)	(1,673)	(121)
Balance, beginning of period at Mar. 31, 2023			1,970		3,780	50,388	(36,980)	(1,673)	(121)
Increase (decrease) in equity
Preferred stock issuance, net of issuance costs			587
Preferred stock redemption			(556)
Equity incentive plans activity, net					6
Net income (loss)	(1,375)					(1,352)			(23)
Dividends on common stock (declared per share of $0.92, $0.89, $1.84, and $1.78 )						(233)
Dividends on preferred stock						(37)
Shares acquired							(154)
Shares reissued under equity incentive plans, net							3
Change in unrealized net capital gains and losses	(272)							(272)	(1)
Change in unrealized foreign currency translation adjustments	28							28
Change in unamortized pension and other postretirement prior service credit	(5)							(5)
Change in discount rate for reserve for future policy benefits	8							8
Capital transaction for noncontrolling interest									0
Balance, end of period at Jun. 30, 2023	15,372	0	2,001	9	3,786	48,766	(37,131)	(1,914)	(145)
Increase (decrease) in equity
Total Allstate shareholders’ equity	15,517
Total equity	15,372	0	2,001	9	3,786	48,766	(37,131)	(1,914)	(145)
Total Allstate shareholders’ equity	17,770
Total equity	17,630		2,001		3,854	49,716	(37,110)	(700)	(140)
Balance, beginning of period at Dec. 31, 2023	17,630		2,001		3,854	49,716	(37,110)	(700)	(140)
Increase (decrease) in equity
Preferred stock issuance, net of issuance costs			0
Preferred stock redemption			0
Equity incentive plans activity, net					73
Net income (loss)	1,545					1,549			(4)
Dividends on common stock (declared per share of $0.92, $0.89, $1.84, and $1.78 )						(488)
Dividends on preferred stock						(59)
Shares acquired							0
Shares reissued under equity incentive plans, net							74
Change in unrealized net capital gains and losses	(334)							(334)	1
Change in unrealized foreign currency translation adjustments	(15)							(15)
Change in unamortized pension and other postretirement prior service credit	(1)							(1)
Change in discount rate for reserve for future policy benefits	24
Capital transaction for noncontrolling interest									123
Balance, end of period at Jun. 30, 2024	18,573	0	2,001	9	3,927	50,718	(37,036)	(1,026)	(20)
Increase (decrease) in equity
Total equity			2,001		3,894	50,662	(37,044)	(883)	(159)
Balance, beginning of period at Mar. 31, 2024			2,001		3,894	50,662	(37,044)	(883)	(159)
Increase (decrease) in equity
Preferred stock issuance, net of issuance costs			0
Preferred stock redemption			0
Equity incentive plans activity, net					33
Net income (loss)	347					331			16
Dividends on common stock (declared per share of $0.92, $0.89, $1.84, and $1.78 )						(245)
Dividends on preferred stock						(30)
Shares acquired							0
Shares reissued under equity incentive plans, net							8
Change in unrealized net capital gains and losses	(119)							(119)	0
Change in unrealized foreign currency translation adjustments	(23)							(23)
Change in unamortized pension and other postretirement prior service credit	0							0
Change in discount rate for reserve for future policy benefits	(1)							(1)
Capital transaction for noncontrolling interest									123
Balance, end of period at Jun. 30, 2024	18,573	0	2,001	9	3,927	50,718	(37,036)	(1,026)	(20)
Increase (decrease) in equity
Total Allstate shareholders’ equity	18,593
Total equity	$ 18,573	$ 0	$ 2,001	$ 9	$ 3,927	$ 50,718	$ (37,036)	$ (1,026)	$ (20)