Derivative Financial Instruments - Narrative (Details)	9 Months Ended
Sep. 30, 2021 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Potential recoveries	$ 0

Represents the potential amount of recoveries under sale of credit protection.

No definition available.

Name:	all_PotentialRecoveriesUnderCreditRiskDerivatives
Namespace Prefix:	all_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration