Condensed Consolidated Statements of Operations (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenues
Net investment income	$ 974	$ 220	$ 1,682	$ 466
Realized capital gains (losses)	287	440	713	278
Total revenues	12,646	10,403	25,097	20,269
Costs and expenses
Property and casualty insurance claims and claims expense	7,207	5,222	13,250	10,563
Shelter-in-Place Payback expense	29	738	29	948
Accident and health insurance policy benefits	244	123	477	264
Interest credited to contractholder funds	8	9	17	18
Amortization of deferred policy acquisition costs	1,545	1,344	3,068	2,709
Operating costs and expenses	1,683	1,394	3,414	2,732
Pension and other postretirement remeasurement (gains) losses	(134)	73	(444)	391
Restructuring and related charges	71	13	122	17
Amortization of purchased intangibles	105	29	158	57
Interest expense	91	79	177	160
Total costs and expenses	10,849	9,024	20,268	17,859
Income from operations before income tax expense	1,797	1,379	4,829	2,410
Income tax expense	362	273	988	467
Net income from continuing operations	1,435	1,106	3,841	1,943
Income (loss) from discontinued operations, net of tax	196	144	(3,597)	(144)
Net income	1,631	1,250	244	1,799
Less: Net income attributable to noncontrolling interest	6	0	0	0
Net income attributable to Allstate	1,625	1,250	244	1,799
Less: Preferred stock dividends	30	26	57	62
Net income applicable to common shareholders	$ 1,595	$ 1,224	$ 187	$ 1,737
Basic
Earnings per common share - Continuing operations basic (in dollars per share)	$ 4.68	$ 3.44	$ 12.59	$ 5.96
Earnings per common share - Discontinued operations basic (in dollars per share)	0.66	0.46	(11.97)	(0.46)
Earnings per common share - Basic (in dollars per share)	5.34	3.90	0.62	5.50
Diluted
Earnings per common share - Continuing operations diluted (in dollars per share)	4.61	3.41	12.41	5.88
Earnings per common share - Discontinued operations diluted (in dollars per share)	0.65	0.45	(11.80)	(0.45)
Earnings per common share - Diluted (in dollars per share)	$ 5.26	$ 3.86	$ 0.61	$ 5.43
Weighted average common shares - Basic (in shares)	298.8	313.7	300.6	315.6
Weighted average common shares - Diluted (in shares)	303.3	317.0	304.9	319.8
Property and casualty insurance premiums
Revenues
Property and casualty insurance premiums	$ 10,444	$ 9,223	$ 20,751	$ 18,458
Accident and health insurance premiums and contract charges
Revenues
Insurance premiums, commissions and fees	447	263	902	545
Other revenue
Revenues
Insurance premiums, commissions and fees	$ 494	$ 257	$ 1,049	$ 522