Reinsurance and indemnification Reinsurance and indemnification recoverables, net (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Reinsurance
Reinsurance and indemnification recoverables, net	$ 9,097	$ 9,211
Property-Liability
Reinsurance
Unpaid losses estimated (including IBNR)	94	112
Unpaid losses estimated (including IBNR)	6,889	6,912
Reinsurance and indemnification recoverables, net	6,983	7,024
Allstate Annuities
Reinsurance
Reinsurance and indemnification recoverables, net	1,309	1,305
Life premiums and contract charges
Reinsurance
Reinsurance and indemnification recoverables, net	718	794
Other personal lines
Reinsurance
Reinsurance and indemnification recoverables, net	$ 87	$ 88

Amount, after valuation allowance, recoverable under reinsurance contracts for losses reported to the ceding insurer but not yet paid and amounts expected for incurred losses and settlement expenses, which have not yet been reported to the ceding insurer.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 310
-Section 45
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=99404803&loc=d3e21412-158489

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 20
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=99397103&loc=d3e6824-158387

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (cc)
-URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437

Name:	us-gaap_ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant