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	Noncontrolling interest
Increase (decrease) in equity
Total equity			$ 1,970		$ 3,498	$ 52,767	$ (31,331)	$ 3,304	$ 0
Balance, beginning of period at Dec. 31, 2020			1,970		3,498	52,767	(31,331)	3,304	0
Increase (decrease) in equity
Acquisition			450						(14)
Preferred stock redemption			(250)
Forward contract on accelerated share repurchase agreement					113
Equity incentive plans activity					57
Net (loss) income	$ 244					244			0
Dividends on common stock (declared per share of $0.85, $0.81, $1.70 and $1.62)						(490)
Dividends on preferred stock						(57)
Shares acquired							(1,163)
Shares reissued under equity incentive plans, net							100
Change in unrealized net capital gains and losses	(1,016)							(1,016)	(1)
Change in unrealized foreign currency translation adjustments	31							31
Change in unamortized pension and other postretirement prior service credit	(29)							(29)
Balance, end of period at Jun. 30, 2021	28,192	$ 0	2,170	$ 9	3,668	52,464	(32,394)	2,290	(15)
Increase (decrease) in equity
Total equity			2,170		3,596	51,107	(31,886)	1,823	(27)
Balance, beginning of period at Mar. 31, 2021			2,170		3,596	51,107	(31,886)	1,823	(27)
Increase (decrease) in equity
Acquisition			0						7
Preferred stock redemption			0
Forward contract on accelerated share repurchase agreement					0
Equity incentive plans activity					72
Net (loss) income	1,631					1,631			6
Dividends on common stock (declared per share of $0.85, $0.81, $1.70 and $1.62)						(244)
Dividends on preferred stock						(30)
Shares acquired							(562)
Shares reissued under equity incentive plans, net							54
Change in unrealized net capital gains and losses	484							484	(1)
Change in unrealized foreign currency translation adjustments	(3)							(3)
Change in unamortized pension and other postretirement prior service credit	(14)							(14)
Balance, end of period at Jun. 30, 2021	28,192	0	2,170	9	3,668	52,464	(32,394)	2,290	(15)
Increase (decrease) in equity
Total Allstate shareholders’ equity	28,207
Total equity	28,192	0	2,170	9	3,668	52,464	(32,394)	2,290	(15)
Total Allstate shareholders’ equity	25,179
Total equity	25,127		1,970		3,722	53,294	(34,471)	655	(52)
Balance, beginning of period at Dec. 31, 2021	25,127		1,970		3,722	53,294	(34,471)	655	(52)
Increase (decrease) in equity
Acquisition			0						0
Preferred stock redemption			0
Forward contract on accelerated share repurchase agreement					0
Equity incentive plans activity					18
Net (loss) income	(378)					(359)			(19)
Dividends on common stock (declared per share of $0.85, $0.81, $1.70 and $1.62)						(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	(2,736)							(2,736)	(20)
Change in unrealized foreign currency translation adjustments	(47)							(47)
Change in unamortized pension and other postretirement prior service credit	(30)							(30)
Balance, end of period at Jun. 30, 2022	20,024	0	1,970	9	3,740	52,412	(35,858)	(2,158)	(91)
Increase (decrease) in equity
Total equity			1,970		3,706	53,688	(35,208)	(953)	(74)
Balance, beginning of period at Mar. 31, 2022			1,970		3,706	53,688	(35,208)	(953)	(74)
Increase (decrease) in equity
Acquisition			0						0
Preferred stock redemption			0
Forward contract on accelerated share repurchase agreement					0
Equity incentive plans activity					34
Net (loss) income	(1,024)					(1,015)			(9)
Dividends on common stock (declared per share of $0.85, $0.81, $1.70 and $1.62)						(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	(1,143)							(1,143)	(8)
Change in unrealized foreign currency translation adjustments	(47)							(47)
Change in unamortized pension and other postretirement prior service credit	(15)							(15)
Balance, end of period at Jun. 30, 2022	20,024	0	1,970	9	3,740	52,412	(35,858)	(2,158)	(91)
Increase (decrease) in equity
Total Allstate shareholders’ equity	20,115
Total equity	$ 20,024	$ 0	$ 1,970	$ 9	$ 3,740	$ 52,412	$ (35,858)	$ (2,158)	$ (91)