Reserve for Future Policy Benefits and Contractholder Funds - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reserve for Future Policy Benefits and Contractholder Funds
Accident, health and other policy benefits, remeasurement (gain) loss (less than $1 million in 2023)	$ 0	$ (4)	$ (11)

Accident, Health And Other Policy Benefits, Remeasurement (Gain) Loss

No definition available.

Name:	all_AccidentHealthAndOtherPolicyBenefitsRemeasurementGainLoss
Namespace Prefix:	all_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration