Condensed Consolidated Statements of Operations (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues
Net investment income	$ 764	$ 464	$ 2,446	$ 930
Realized capital gains (losses)	105	319	818	597
Total revenues	12,480	10,678	37,577	30,947
Costs and expenses
Property and casualty insurance claims and claims expense	8,264	6,072	21,514	16,635
Shelter-in-Place Payback expense	0	0	29	948
Accident and health insurance policy benefits	269	128	746	392
Interest credited to contractholder funds	8	8	25	26
Amortization of deferred policy acquisition costs	1,582	1,386	4,650	4,095
Operating costs and expenses	1,890	1,322	5,304	4,054
Pension and other postretirement remeasurement (gains) losses	40	(71)	(404)	320
Restructuring and related charges	23	196	145	213
Amortization of purchased intangibles	109	31	267	88
Interest expense	69	78	246	238
Total costs and expenses	12,254	9,150	32,522	27,009
Income from operations before income tax expense	226	1,528	5,055	3,938
Income tax expense	20	312	1,008	779
Net income from continuing operations	206	1,216	4,047	3,159
Income (loss) from discontinued operations, net of tax	325	(63)	(3,272)	(207)
Net income	531	1,153	775	2,952
Less: Net loss attributable to noncontrolling interest	(7)	0	(7)	0
Net income attributable to Allstate	538	1,153	782	2,952
Less: Preferred stock dividends	30	27	87	89
Net income applicable to common shareholders	$ 508	$ 1,126	$ 695	$ 2,863
Basic
Earnings per common share - Continuing operations basic (in dollars per share)	$ 0.62	$ 3.82	$ 13.31	$ 9.77
Earnings per common share - Discontinued operations basic (in dollars per share)	1.11	(0.20)	(10.98)	(0.66)
Earnings per common share - Basic (in dollars per share)	1.73	3.62	2.33	9.11
Diluted
Earnings per common share - Continuing operations diluted (in dollars per share)	0.62	3.78	13.11	9.66
Earnings per common share - Discontinued operations diluted (in dollars per share)	1.09	(0.20)	(10.81)	(0.65)
Earnings per common share - Diluted (in dollars per share)	$ 1.71	$ 3.58	$ 2.30	$ 9.01
Weighted average common shares - Basic (in shares)	293.1	311.2	298.1	314.1
Weighted average common shares - Diluted (in shares)	297.9	314.1	302.6	317.9
Property and casualty insurance premiums
Revenues
Property and casualty insurance premiums	$ 10,615	$ 9,336	$ 31,366	$ 27,794
Accident and health insurance premiums and contract charges
Revenues
Insurance premiums, commissions and fees	460	287	1,362	832
Other revenue
Revenues
Insurance premiums, commissions and fees	$ 536	$ 272	$ 1,585	$ 794