v3.26.1
Reportable Segments - Schedule of Reportable Segments Expense Information Used in Measure for Segment Profit or Loss (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Segment Reporting        
Prior year reserve reestimates excluding catastrophes $ (641) $ (370) $ (1,645) $ (621)
Accident, health and other policy benefits 72 188 148 521
Amortization of DAC 2,202 2,076 4,380 4,163
Amortization of purchased intangibles 46 57 93 116
Interest expense 96 100 194 200
Restructuring and related charges 7 15 12 31
Income Tax Expense (Benefit) 871 604 1,521 727
Preferred stock dividends 30 30 59 59
Non-catastrophe losses        
Segment Reporting        
Prior year reserve reestimates excluding catastrophes (692) (376) (1,708) (611)
Catastrophe        
Segment Reporting        
Prior year reserve reestimates excluding catastrophes 51 6 63 (10)
Loss adjustment expenses, net of reinsurance     2,960 4,190
Operating segments | Allstate Protection | Allstate Protection        
Segment Reporting        
Property and casualty insurance claims and claims expense 8,638 8,470 17,406 17,163
Amortization of DAC 1,840 1,742 3,661 3,474
Advertising expense 524 442 1,068 965
Amortization of purchased intangibles 38 46 77 92
Restructuring and related charges 6 13 7 29
Other segment expenses 1,404 1,242 2,694 2,419
Total 13,480 13,567 26,167 27,718
Loss adjustment expenses, net of reinsurance 799 750 1,580 1,480
Operating segments | Allstate Protection | Allstate Protection | Non-catastrophe losses        
Segment Reporting        
Prior year reserve reestimates excluding catastrophes (692) (378) (1,708) (616)
Operating segments | Allstate Protection | Allstate Protection | Catastrophe        
Segment Reporting        
Property and casualty insurance claims and claims expense 1,722 1,990 2,962 4,192
Operating segments | Allstate Protection | Run-off Property-Liability        
Segment Reporting        
Property and casualty insurance claims and claims expense 0 2 0 5
Other segment expenses 0 1 1 2
Total 0 3 1 7
Operating segments | Protection Services        
Segment Reporting        
Property and casualty insurance claims and claims expense 198 170 397 331
Amortization of DAC 356 328 704 646
Non-deferrable commissions 124 110 250 211
Restructuring and related charges 0 1 4 1
Other segment expenses 186 180 369 388
Income Tax Expense (Benefit) 19 18 34 35
Total 883 807 1,758 1,612
Operating segments | Allstate Health and Benefits        
Segment Reporting        
Accident, health and other policy benefits 0 121 0 379
Amortization of DAC 0 0 0 30
Other segment expenses 0 71 0 213
Income Tax Expense (Benefit) 0 2 0 12
Total 0 194 0 634
Operating segments | Corporate        
Segment Reporting        
Interest expense 96 100 194 200
Other segment expenses 33 45 66 77
Income Tax Expense (Benefit) (3) (21) (19) (48)
Preferred stock dividends 30 30 59 59
Total $ 156 $ 154 $ 300 $ 288