Condensed Consolidated Statements of Comprehensive Income (Loss) (unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Statement of Comprehensive Income [Abstract]
Net income	$ 3,744	$ 1,164	$ 6,439	$ 2,709
Changes in:
Unrealized net capital gains and losses	315	1,299	1,122	965
Unrealized foreign currency translation adjustments	40	14	79	(1)
Unamortized pension and other postretirement prior service credit	(1)	0	(1)	(1)
Discount rate for reserve for future policy benefits	1	(36)	(13)	(12)
Other comprehensive income, after-tax	355	1,277	1,187	951
Comprehensive income	4,099	2,441	7,626	3,660
Less: Comprehensive loss attributable to noncontrolling interest	(2)	(19)	(8)	(22)
Comprehensive income attributable to Allstate	$ 4,101	$ 2,460	$ 7,634	$ 3,682