Condensed Consolidated Statements of Shareholders’ Equity (unaudited) - USD ($) $ in Millions	Total	Preferred Stock	Preferred stock additional capital paid-in	Common stock par value	Common stock additional capital paid-in	Retained income	Retained income Cumulative effect of change in accounting principle	Treasury stock	Accumulated other comprehensive income (loss)	Noncontrolling Interest
Increase (decrease) in equity
Total equity			$ 2,248		$ 3,463	$ 48,074	$ (88)	$ (29,746)	$ 1,950	$ 0
Balance, beginning of period at Dec. 31, 2019			2,248		3,463	48,074	(88)	(29,746)	1,950	0
Increase (decrease) in equity
Acquisition			0							0
Preferred stock redemption			(278)
Forward contract on accelerated share repurchase agreement					75
Equity incentive plans activity					3
Net income	$ 1,799					1,799				0
Dividends on common stock (declared per share of $0.81, $0.54, $1.62 and $1.08)						(343)
Dividends on preferred stock						(62)
Shares acquired								(902)
Shares reissued under equity incentive plans, net								106
Change in unrealized net capital gains and losses	715								715	0
Change in unrealized foreign currency translation adjustments	(30)								(30)
Change in unamortized pension and other postretirement prior service credit	(7)								(7)
Balance, end of period at Jun. 30, 2020	26,986	$ 0	1,970	$ 9	3,541	49,380		(30,542)	2,628	0
Increase (decrease) in equity
Total equity			1,970		3,519	48,326	0	(30,209)	558	0
Balance, beginning of period at Mar. 31, 2020			1,970		3,519	48,326	0	(30,209)	558	0
Increase (decrease) in equity
Acquisition			0							0
Preferred stock redemption			0
Forward contract on accelerated share repurchase agreement					0
Equity incentive plans activity					22
Net income	1,250					1,250				0
Dividends on common stock (declared per share of $0.81, $0.54, $1.62 and $1.08)						(170)
Dividends on preferred stock						(26)
Shares acquired								(391)
Shares reissued under equity incentive plans, net								58
Change in unrealized net capital gains and losses	2,072								2,072	0
Change in unrealized foreign currency translation adjustments	9								9
Change in unamortized pension and other postretirement prior service credit	(11)								(11)
Balance, end of period at Jun. 30, 2020	26,986	0	1,970	9	3,541	49,380		(30,542)	2,628	0
Increase (decrease) in equity
Total Allstate shareholders’ equity	26,986
Total equity	26,986	0	1,970	9	3,541	49,380		(30,542)	2,628	0
Total Allstate shareholders’ equity	30,217
Total equity	30,217		1,970		3,498	52,767	0	(31,331)	3,304	0
Balance, beginning of period at Dec. 31, 2020	30,217		1,970		3,498	52,767	0	(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 income	244					244				0
Dividends on common stock (declared per share of $0.81, $0.54, $1.62 and $1.08)						(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	0	(31,886)	1,823	(27)
Balance, beginning of period at Mar. 31, 2021			2,170		3,596	51,107	$ 0	(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 income	1,631					1,631				6
Dividends on common stock (declared per share of $0.81, $0.54, $1.62 and $1.08)						(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)