Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 4,599	$ (213)	$ (1,342)
Changes in:
Unrealized net capital gains and losses	(167)	1,651	(2,853)
Unrealized foreign currency translation adjustments	(47)	67	(150)
Unamortized pension and other postretirement prior service credit	(2)	(16)	(43)
Discount rate for reserve for future policy benefits	27	(10)	228
Other comprehensive (loss) income, after-tax	(189)	1,692	(2,818)
Comprehensive income (loss)	4,410	1,479	(4,160)
Less: Comprehensive loss attributable to noncontrolling interest	(58)	(15)	(73)
Comprehensive income (loss) attributable to Allstate	$ 4,468	$ 1,494	$ (4,087)