Reportable Segments - Performance data and tax items (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information
Amortization of DAC	$ 6,644	$ 6,252	$ 5,477
Income tax expense (benefit)	(494)	1,289	1,373
Property-Liability
Segment Reporting Information
Amortization of DAC	5,570	5,313	4,642
Income tax expense (benefit)	(427)	1,151	1,382
Protection Services
Segment Reporting Information
Amortization of DAC	928	795	658
Income tax expense (benefit)	5	39	26
Allstate Health and Benefits
Segment Reporting Information
Amortization of DAC	146	144	177
Income tax expense (benefit)	39	50	28
Corporate and Other
Segment Reporting Information
Income tax expense (benefit)	$ (111)	$ 49	$ (63)