Reinsurance and Indemnification - Life and annuity reinsurance recoverables (Details) - Allstate Annuities	12 Months Ended
Dec. 31, 2020 reinsurer
Reinsurance Retention Policy [Line Items]
Percent of morbidity risk ceded for term-life insurance policies	90.00%
Number of unaffiliated reinsurers	14

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