| Cover | Aug. 01, 2019 |
| Document Information [Line Items] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Aug. 1, 2019 |
| Entity File Number | 1-11840 |
| Entity Registrant Name | ALLSTATE CORP |
| Entity Central Index Key | 0000899051 |
| Entity Tax Identification Number | 36-3871531 |
| Entity Incorporation, State or Country Code | DE |
| 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 |
| Common Stock | NEW YORK STOCK EXCHANGE, INC. [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Common Stock, par value $0.01 per share |
| Trading Symbol | ALL |
| Security Exchange Name | NYSE |
| Common Stock | CHICAGO STOCK EXCHANGE, INC [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Common Stock, par value $0.01 per share |
| Trading Symbol | ALL |
| Security Exchange Name | CHX |
| Subordinated Debentures Due 2053 at 5.10 Percent [Member] | |
| 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 A Preferred Stock [Member] | |
| 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 A |
| Trading Symbol | ALL PR A |
| Security Exchange Name | NYSE |
| Series D Preferred Stock [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Depositary Shares represent 1/1,000th of a share of 6.625% Noncumulative Preferred Stock, Series D |
| Trading Symbol | ALL PR D |
| Security Exchange Name | NYSE |
| Series E Preferred Stock [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Depositary Shares represent 1/1,000th of a share of 6.625% Noncumulative Preferred Stock, Series E |
| Trading Symbol | ALL PR E |
| Security Exchange Name | NYSE |
| Series F Preferred Stock [Member] | |
| Document Information [Line Items] | |
| Title of 12(b) Security | Depositary Shares represent 1/1,000th of a share of 6.250% Noncumulative Preferred Stock, Series F |
| Trading Symbol | ALL PR F |
| Security Exchange Name | NYSE |
| Series G Preferred Stock [Member] | |
| 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 |
