Reportable Segments - Total assets and investments (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information
Assets	$ 97,957	$ 99,440
Investments	61,829	64,701
Deferred policy acquisition costs	5,418	4,722	$ 3,774	$ 3,600
Property-Liability
Segment Reporting Information
Assets	82,744	84,846
Investments	54,011	57,258
Deferred policy acquisition costs	2,146	1,951
Protection Services
Segment Reporting Information
Assets	6,922	6,909
Investments	1,917	1,890
Deferred policy acquisition costs	2,768	2,294
Allstate Health and Benefits
Segment Reporting Information
Assets	3,720	4,015
Investments	1,872	2,191
Deferred policy acquisition costs	504	477
Corporate and Other
Segment Reporting Information
Assets	4,571	3,670
Investments	$ 4,029	$ 3,362