Variable Interest Entities - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Variable Interest Entity [Line Items]
Insurance premiums	$ 44,039	$ 38,167	$ 37,221
Incurred claims and claims expenses	29,318	$ 22,001	$ 23,976
Variable Interest Entity, Primary Beneficiary | Allstate Protection
Variable Interest Entity [Line Items]
Insurance premiums	181
Incurred claims and claims expenses	$ 135