Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 10,266	$ 4,599	$ (213)
Changes in:
Unrealized net capital gains and losses	1,068	(167)	1,651
Unrealized foreign currency translation adjustments	90	(47)	67
Unamortized pension and other postretirement prior service credit	0	(2)	(16)
Discount rate for reserve for future policy benefits	(14)	27	(10)
Other comprehensive income (loss), after-tax	1,144	(189)	1,692
Comprehensive income	11,410	4,410	1,479
Less: Comprehensive loss attributable to noncontrolling interest	(13)	(58)	(15)
Comprehensive income attributable to Allstate	$ 11,423	$ 4,468	$ 1,494