Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenues
Accident and health insurance premiums and contract charges	$ 52,516	$ 47,736	$ 44,052
Other revenue	2,400	2,344	2,172
Net investment income	2,478	2,403	3,293
Net gains (losses) on investments and derivatives	(300)	(1,072)	1,084
Total revenues	57,094	51,411	50,601
Costs and expenses
Property and casualty insurance claims and claims expense	41,070	37,264	29,318
Shelter-in-Place Payback expense	0	0	29
Accident, health and other policy benefits (including remeasurement (gains) losses of $0, $(4), and $(11))	1,071	1,042	1,060
Amortization of deferred policy acquisition costs	7,278	6,634	6,236
Operating costs and expenses	7,137	7,446	7,260
Pension and other postretirement remeasurement (gains) losses	9	116	(644)
Restructuring and related charges	169	51	170
Amortization of purchased intangibles	329	353	376
Interest expense	379	335	330
Total costs and expenses	57,442	53,241	44,135
(Loss) income from operations before income tax expense	(348)	(1,830)	6,466
Income tax (benefit) expense	(135)	(488)	1,292
Net (loss) income from continuing operations	(213)	(1,342)	5,174
Loss from discontinued operations, net of tax	0	0	(3,593)
Net (loss) income	(213)	(1,342)	1,581
Less: Net loss attributable to noncontrolling interest	(25)	(53)	(33)
Net (loss) income attributable to Allstate	(188)	(1,289)	1,614
Less: Preferred stock dividends	128	105	114
Net (loss) income applicable to common shareholders, basic	(316)	(1,394)	1,500
Net (loss) income applicable to common shareholders, diluted	$ (316)	$ (1,394)	$ 1,500
Basic
Continuing operations (in dollars per share)	$ (1.20)	$ (5.14)	$ 17.28
Discontinued operations (in dollars per share)	0	0	(12.19)
Total (in dollars per share)	(1.20)	(5.14)	5.09
Diluted
Continuing operations (in dollars per share)	(1.20)	(5.14)	17.03
Discontinued operations (in dollars per share)	0	0	(12.02)
Total (in dollars per share)	$ (1.20)	$ (5.14)	$ 5.01
Weighted average common shares - Basic (in shares)	262.5	271.2	294.8
Weighted average common shares - Diluted (in shares)	262.5	271.2	299.1
Property and casualty insurance premiums
Revenues
Accident and health insurance premiums and contract charges	$ 50,670	$ 45,904	$ 42,218
Accident and health insurance premiums and contract charges
Revenues
Accident and health insurance premiums and contract charges	$ 1,846	$ 1,832	$ 1,834