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		$ 3,722	$ 53,288	$ (34,471)	$ 426	$ (52)
Balance, beginning of period at Dec. 31, 2021			1,970		3,722	53,288	(34,471)	426	(52)
Increase (decrease) in equity
Preferred stock issuance, net of issuance costs			0
Preferred stock redemption			0
Equity incentive plans activity					18
Net loss	$ (372)					(353)			(19)
Dividends on common stock (declared per share of $0.89, $0.85, $1.78 and $1.70)						(470)
Dividends on preferred stock						(53)
Shares acquired							(1,477)
Shares reissued under equity incentive plans, net							90
Change in unrealized net capital gains and losses	(2,738)							(2,738)	(20)
Change in unrealized foreign currency translation adjustments	(47)							(47)
Change in unamortized pension and other postretirement prior service credit	(30)							(30)
Change in discount rate for reserve for future policy benefits	180							180
Balance, end of period at Jun. 30, 2022	19,973	$ 0	1,970	$ 9	3,740	52,412	(35,858)	(2,209)	(91)
Increase (decrease) in equity
Total equity			1,970		3,706	53,686	(35,208)	(1,088)	(74)
Balance, beginning of period at Mar. 31, 2022			1,970		3,706	53,686	(35,208)	(1,088)	(74)
Increase (decrease) in equity
Preferred stock issuance, net of issuance costs			0
Preferred stock redemption			0
Equity incentive plans activity					34
Net loss	(1,022)					(1,013)			(9)
Dividends on common stock (declared per share of $0.89, $0.85, $1.78 and $1.70)						(234)
Dividends on preferred stock						(27)
Shares acquired							(683)
Shares reissued under equity incentive plans, net							33
Change in unrealized net capital gains and losses	(1,144)							(1,144)	(8)
Change in unrealized foreign currency translation adjustments	(47)							(47)
Change in unamortized pension and other postretirement prior service credit	(15)							(15)
Change in discount rate for reserve for future policy benefits	85							85
Balance, end of period at Jun. 30, 2022	19,973	0	1,970	9	3,740	52,412	(35,858)	(2,209)	(91)
Increase (decrease) in equity
Total Allstate shareholders’ equity	20,064
Total equity	19,973	0	1,970	9	3,740	52,412	(35,858)	(2,209)	(91)
Total Allstate shareholders’ equity	17,488
Total equity	17,363		1,970		3,788	50,970	(36,857)	(2,392)	(125)
Balance, beginning of period at Dec. 31, 2022	17,363		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					(2)
Net loss	(1,696)					(1,672)			(24)
Dividends on common stock (declared per share of $0.89, $0.85, $1.78 and $1.70)						(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)
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					6
Net loss	(1,375)					(1,352)			(23)
Dividends on common stock (declared per share of $0.89, $0.85, $1.78 and $1.70)						(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
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)