Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (1,364)	$ 1,566	$ 5,576
Changes in:
Unrealized net capital gains and losses	(2,851)	(2,582)	1,293
Unrealized foreign currency translation adjustments	(150)	(8)	52
Unamortized pension and other postretirement prior service credit	(43)	(59)	9
Other comprehensive (loss) income, after-tax	(3,044)	(2,649)	1,354
Comprehensive (loss) income	(4,408)	(1,083)	6,930
Less: Comprehensive loss attributable to noncontrolling interest	(73)	(36)	0
Comprehensive (loss) income attributable to Allstate	$ (4,335)	$ (1,047)	$ 6,930