Condensed Consolidated Statements of Comprehensive Income (Loss) (unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 347	$ (1,375)	$ 1,545	$ (1,696)
Changes in:
Unrealized net capital gains and losses	(119)	(272)	(334)	410
Unrealized foreign currency translation adjustments	(23)	28	(15)	78
Unamortized pension and other postretirement prior service credit	0	(5)	(1)	(9)
Discount rate for reserve for future policy benefits	(1)	8	24	(1)
Other comprehensive (loss) income, after-tax	(143)	(241)	(326)	478
Comprehensive income (loss)	204	(1,616)	1,219	(1,218)
Less: Comprehensive income (loss) attributable to noncontrolling interest	16	(24)	(3)	(20)
Comprehensive income (loss) attributable to Allstate	$ 188	$ (1,592)	$ 1,222	$ (1,198)