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, 2023	Dec. 31, 2022	Dec. 31, 2021
Amount per statutory accounting practices
Net income (loss)	$ (426)	$ (1,583)	$ 7,713
Capital and surplus	14,560	15,276
Life and annuity business sold | Disposal Group, Disposed of by Sale, Not Discontinued Operations
Amount per statutory accounting practices
Net income (loss)	0	0	1,642
Capital and surplus	0	0
Property and casualty insurance
Amount per statutory accounting practices
Net income (loss)	(487)	(1,653)	5,975
Capital and surplus	14,250	14,997
Life, accident and health insurance
Amount per statutory accounting practices
Net income (loss)	61	70	$ 96
Capital and surplus	$ 310	$ 279