Statutory Financial Information and Dividend Limitations - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Dividend Limitations
Action level RBC expressed as a multiplier of authorized control level RBC, which if not achieved would require specific actions to be taken	2
Capital and surplus	$ 21,383	$ 20,400
Restricted net assets	31,030
Allstate Insurance Company
Dividend Limitations
Dividends paid	4,440
Maximum amount of dividends without prior approval	$ 5,950
Advance notice period required for payment of dividend in excess of amount available for distribution without prior approval	30 days
Unassigned surplus excluding unrealized appreciation from investments	$ 13,520
Capital and surplus	20,540
Authorized control level RBC	$ 2,920