Variable Interest Entities - Narrative (Details) - Variable Interest Entity, Primary Beneficiary - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Variable Interest Entity [Line Items]
Notes payable	$ 123		$ 123		$ 123
Allstate Protection
Variable Interest Entity [Line Items]
Property and casualty insurance premiums	39	$ 47	122	$ 137
Incurred expense (adjustment)	$ 31	$ 38	$ 91	$ 105