Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues
Insurance premiums	$ 44,039	$ 38,167	$ 37,221
Net investment income	3,293	1,590	1,728
Net gains (losses) on investments and derivatives	1,084	1,087	1,538
Total revenues	50,588	41,909	41,541
Costs and expenses
Property and casualty insurance claims and claims expense (net of reinsurance ceded and indemnification programs of $3,484, $530 and $524)	29,318	22,001	23,976
Shelter-in-Place Payback expense	29	948	0
Accident and health insurance policy benefits (net of reinsurance ceded of $85, $15 and $12)	1,015	516	601
Interest credited to contractholder funds (net of reinsurance ceded of $1, zero and zero)	34	33	34
Amortization of deferred policy acquisition costs	6,252	5,477	5,353
Operating costs and expenses	7,260	5,494	5,422
Pension and other postretirement remeasurement (gains) losses	(644)	(51)	114
Restructuring and related charges	170	253	39
Amortization of purchased intangibles	376	118	126
Impairment of purchased intangibles	0	0	106
Interest expense	330	318	327
Total costs and expenses	44,140	35,107	36,098
Income from operations before income tax expense	6,448	6,802	5,443
Income tax expense	1,289	1,373	1,116
Net income from continuing operations	5,159	5,429	4,327
(Loss) income from discontinued operations, net of tax	(3,593)	147	520
Net income	1,566	5,576	4,847
Less: Net loss attributable to noncontrolling interest	(33)	0	0
Net income attributable to Allstate	1,599	5,576	4,847
Less: Preferred stock dividends	114	115	169
Net income applicable to common shareholders	$ 1,485	$ 5,461	$ 4,678
Basic
Continuing operations (in dollars per share)	$ 17.23	$ 17.06	$ 12.67
Discontinued operations (in dollars per share)	(12.19)	0.47	1.58
Earnings per common share - Basic (in dollars per share)	5.04	17.53	14.25
Diluted
Continuing operations (in dollars per share)	16.98	16.84	12.47
Discontinued operations (in dollars per share)	(12.02)	0.47	1.56
Earnings per common share - Diluted (in dollars per share)	$ 4.96	$ 17.31	$ 14.03
Weighted average common shares - Basic (in shares)	294.8	311.6	328.2
Weighted average common shares - Diluted (in shares)	299.1	315.5	333.5
Property and casualty insurance premiums
Revenues
Insurance premiums	$ 42,218	$ 37,073	$ 36,076
Accident and health insurance premiums
Revenues
Insurance premiums	1,821	1,094	1,145
Other revenue
Revenues
Other revenue	$ 2,172	$ 1,065	$ 1,054