Statutory Financial Information and Dividend Limitations - Schedule of Statutory Net Income (Loss) and Capital and Surplus of Allstate’s Domestic Insurance Subsidiaries (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Amount per statutory accounting practices
Net income (loss)	$ 4,219	$ (426)	$ (1,583)
Capital and surplus	18,635	14,560
Property and casualty insurance
Amount per statutory accounting practices
Net income (loss)	4,158	(487)	(1,653)
Capital and surplus	18,243	14,250
Life, accident and health insurance
Amount per statutory accounting practices
Net income (loss)	61	61	$ 70
Capital and surplus	$ 392	$ 310