Variable Interest Entities - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Losses from catastrophes, net of recoveries	$ 37,264	$ 29,318	$ 22,001
Property and casualty insurance premiums (net of reinsurance ceded and indemnification programs of $1,869, $1,904 and $1,141)	47,737	44,039	$ 38,167
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Notes payable	123	123
Variable Interest Entity, Primary Beneficiary | Allstate Protection
Variable Interest Entity [Line Items]
Losses from catastrophes, net of recoveries	130	135
Property and casualty insurance premiums (net of reinsurance ceded and indemnification programs of $1,869, $1,904 and $1,141)	$ 164	$ 181