Consolidated Statements of Shareholders’ Equity - 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	Parent
Balance, beginning of year at Dec. 31, 2021			$ 1,970		$ 3,722	$ 53,288	$ (34,471)	$ 426	$ (52)
Increase (decrease) in equity [Roll forward]
Preferred stock issuance, net of issuance costs			0
Preferred stock redemption			0
Equity incentive plans activity, net					66
Net income (loss)	$ (1,342)					(1,289)			(53)
Dividends on common stock (declared per share of $3.68, $3.56 and $3.40)						(924)
Dividends on preferred stock						(105)
Shares acquired							(2,496)
Shares reissued under equity incentive plans, net							110
Change in unrealized net capital gains and losses	(2,853)							(2,853)
Change in unrealized foreign currency translation adjustments	(150)							(150)
Change in unamortized pension and other postretirement prior service credit	(43)							(43)
Change in discount rate for reserve for future policy benefits	228							228
Capital transaction for noncontrolling interest									0
Balance, end of year at Dec. 31, 2022	17,363	$ 0	1,970	$ 9	3,788	50,970	(36,857)	(2,392)	(125)	$ 17,488
Increase (decrease) in equity [Roll forward]
Preferred stock issuance, net of issuance costs			587
Preferred stock redemption			(556)
Equity incentive plans activity, net					66
Net income (loss)	(213)					(188)			(25)
Dividends on common stock (declared per share of $3.68, $3.56 and $3.40)						(938)
Dividends on preferred stock						(128)
Shares acquired							(332)
Shares reissued under equity incentive plans, net							79
Change in unrealized net capital gains and losses	1,651							1,651
Change in unrealized foreign currency translation adjustments	67							67
Change in unamortized pension and other postretirement prior service credit	(16)							(16)
Change in discount rate for reserve for future policy benefits	(10)							(10)
Capital transaction for noncontrolling interest									0
Balance, end of year at Dec. 31, 2023	17,630	0	2,001	9	3,854	49,716	(37,110)	(700)	(140)	17,770
Increase (decrease) in equity [Roll forward]
Total Allstate shareholders’ equity	17,770
Preferred stock issuance, net of issuance costs			0
Preferred stock redemption			0
Equity incentive plans activity, net					175
Net income (loss)	4,599					4,667			(68)
Dividends on common stock (declared per share of $3.68, $3.56 and $3.40)						(978)
Dividends on preferred stock						(117)
Shares acquired							0
Shares reissued under equity incentive plans, net							114
Change in unrealized net capital gains and losses	(167)							(167)
Change in unrealized foreign currency translation adjustments	(47)							(47)
Change in unamortized pension and other postretirement prior service credit	(2)							(2)
Change in discount rate for reserve for future policy benefits	27							27
Capital transaction for noncontrolling interest									123
Balance, end of year at Dec. 31, 2024	21,367	$ 0	$ 2,001	$ 9	$ 4,029	$ 53,288	$ (36,996)	$ (889)	$ (75)	$ 21,442
Increase (decrease) in equity [Roll forward]
Total Allstate shareholders’ equity	$ 21,442