Variable Interest Entities - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Variable Interest Entity [Line Items]
Accident and health insurance premiums and contract charges	$ 52,516	$ 47,736	$ 44,052
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]
Accident and health insurance premiums and contract charges	224	164	181
Costs and expenses	$ 251	$ 244	$ 248