General (Details) - USD ($) $ in Millions		3 Months Ended
	Oct. 18, 2022	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease to equity			$ (17,561)		$ (25,127)	$ (26,707)
Subsequent Event
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Proceeds from sale of headquarters	$ 232
Forecast
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Gain on sale of headquarters		$ 99
Accumlated Other Comprehensive Income
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease to equity			3,043	$ 2,158	(655)	(1,918)	$ (2,290)	$ (3,304)
Retained income
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease to equity			$ (51,490)	$ (52,412)	$ (53,294)	$ (52,736)	$ (52,464)	$ (52,767)
Minimum | Forecast | Cumulative effect of change in accounting principle
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease to equity		250
Minimum | Accumlated Other Comprehensive Income | Forecast | Cumulative effect of change in accounting principle
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease to equity		235
Minimum | Retained income | Forecast | Cumulative effect of change in accounting principle
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease to equity		15
Maximum | Forecast | Cumulative effect of change in accounting principle
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease to equity		350
Maximum | Accumlated Other Comprehensive Income | Forecast | Cumulative effect of change in accounting principle
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease to equity		315
Maximum | Retained income | Forecast | Cumulative effect of change in accounting principle
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease to equity		35
Allstate Protection | Forecast | Net Gains (Losses) On Investments And Derivatives
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Gain on sale of headquarters		16
Corporate Segment | Forecast | Other Income
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Gain on sale of headquarters		$ 83