| Document and Entity Information Document | Apr. 21, 2022 | Apr. 11, 2022 |
| Document Information [Line Items] | ||
| Document Type | 8-K | |
| Document Period End Date | Apr. 5, 2022 | |
| Entity Registrant Name | ALLSTATE CORP | |
| Entity Incorporation, State or Country Code | DE | |
| Entity File Number | 1-11840 | |
| Entity Tax Identification Number | 36-3871531 | |
| Entity Address, Address Line One | 2775 Sanders Road | |
| Entity Address, City or Town | Northbrook | |
| Entity Address, State or Province | IL | |
| Entity Address, Postal Zip Code | 60062 | |
| City Area Code | 847 | |
| Local Phone Number | 402-5000 | |
| Written Communications | false | |
| Soliciting Material | false | |
| Pre-commencement Tender Offer | false | |
| Pre-commencement Issuer Tender Offer | false | |
| Entity Emerging Growth Company | false | |
| Amendment Flag | false | |
| Entity Central Index Key | 0000899051 | |
| Common Stock | NEW YORK STOCK EXCHANGE, INC. | ||
| Document Information [Line Items] | ||
| Title of 12(b) Security | Common Stock, par value $.01 per share | |
| Trading Symbol | ALL | |
| Security Exchange Name | NYSE | |
| Common Stock | CHICAGO STOCK EXCHANGE, INC | ||
| Document Information [Line Items] | ||
| Title of 12(b) Security | Common Stock, par value $.01 per share | |
| Trading Symbol | ALL | |
| Security Exchange Name | CHX | |
| Subordinated Debentures Due 2053 at 5.10 Percent | ||
| Document Information [Line Items] | ||
| Title of 12(b) Security | 5.100% Fixed-to-Floating Rate Subordinated Debentures due 2053 | |
| Trading Symbol | ALL.PR.B | |
| Security Exchange Name | NYSE | |
| Series G Preferred Stock | ||
| Document Information [Line Items] | ||
| Title of 12(b) Security | Depositary Shares represent 1/1,000th of a share of 5.625% Noncumulative Preferred Stock, Series G | |
| Trading Symbol | ALL PR G | |
| Security Exchange Name | NYSE | |
| Series H Preferred Stock | ||
| Document Information [Line Items] | ||
| Title of 12(b) Security | Depositary Shares represent 1/1,000th of a share of 5.100% Noncumulative Preferred Stock, Series H | |
| Trading Symbol | ALL PR H | |
| Security Exchange Name | NYSE | |
| Series I Preferred Stock | ||
| Document Information [Line Items] | ||
| Title of 12(b) Security | Depositary Shares represent 1/1,000th of a share of 4.750% Noncumulative Preferred Stock, Series I | |
| Trading Symbol | ALL PR I | |
| Security Exchange Name | NYSE |
