Reinsurance and Indemnification - Retention limits by period of policy issuance (Details) - Allstate Annuities - USD ($) $ in Millions	1 Months Ended	45 Months Ended	48 Months Ended	69 Months Ended	106 Months Ended
	Aug. 31, 1998	Mar. 31, 2011	Mar. 31, 2015	Dec. 31, 2020	Jun. 30, 2007
Reinsurance Retention Policy [Line Items]
Retention level per claim	$ 1	$ 5			$ 2
Retention level for contracts issued to individuals age 70 and over		3
Retention level for certain large contracts meeting specific criteria		$ 10			$ 5
Single life
Reinsurance Retention Policy [Line Items]
Retention level per claim			$ 5	$ 2
Retention level for contracts issued to individuals age 70 and over			3
Retention level for certain large contracts meeting specific criteria			10
Joint life
Reinsurance Retention Policy [Line Items]
Retention level per claim			8
Retention level for certain large contracts meeting specific criteria			$ 10