XML 230 R124.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Reinsurance and Indemnification - Per Occurrence Excess Agreement (Details) $ in Millions | 9 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2017 USD ($) | Dec. 31, 2019 USD ($) state layer reinstatement | Mar. 31, 2019 USD ($)
Reinsurance Retention Policy [Line Items] |  |  |
Limit of aggregate losses under aggregate excess agreement |  | $ 3,400 |
2018-1 Excess Catastrophe Reinsurance Contract |  |  |
Reinsurance Retention Policy [Line Items] |  |  |
Retention percentage of reinsurance limit |  | 100.00% | 100.00%
Limit of aggregate losses under aggregate excess agreement | $ 500 | $ 500 | $ 500
Number of states covered by reinsurance agreement | state |  | 49 |
Term of catastrophe reinsurance agreement contract |  | 4 years |
Catastrophe Reinsurance First Five Layers |  |  |
Reinsurance Retention Policy [Line Items] |  |  |
Number of layers subject to reinstatement in which catastrophe reinsurance agreement contracts are placed | layer |  | 3 |
Retention percentage of reinsurance limit |  | 95.00% |
Catastrophe Reinsurance Sixth Layer |  |  |
Reinsurance Retention Policy [Line Items] |  |  |
Retention percentage of reinsurance limit |  | 95.00% |
Limit of aggregate losses under aggregate excess agreement |  | $ 324 |
Term of catastrophe reinsurance agreement contract |  | 7 years |
Catastrophe Reinsurance Seventh Layer |  |  |
Reinsurance Retention Policy [Line Items] |  |  |
Retention percentage of reinsurance limit |  | 29.37% |
Retention amount for catastrophe reinsurance agreement contracts |  | $ 446 |
Number of reinstatements each year for each contract | reinstatement |  | 1 |
Minimum | 2018-1 Excess Catastrophe Reinsurance Contract |  |  |
Reinsurance Retention Policy [Line Items] |  |  |
Retention amount for catastrophe reinsurance agreement contracts |  | $ 3,940 | $ 4,360

X
- Definition Represents the retention percentage of annual coverage limit provided by the insurance arrangement for catastrophe claims. + References No definition available. + Details
Name: | all_CatastropheInsuranceAnnualCoverageLimitRetentionPercentage
Namespace Prefix: | all_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of reinstatements each year for each contract. + References No definition available. + Details
Name: | all_CatastropheInsuranceNumberOfReinstatementsPerYear
Namespace Prefix: | all_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The limit of aggregated losses per contract year beyond which coverage provided by an aggregate excess agreement applies. + References No definition available. + Details
Name: | all_CatastropheReinsuranceAggregateLossLimitPerContractYear
Namespace Prefix: | all_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the number of layers subject to reinstatement in which catastrophe reinsurance agreement contracts are placed. + References No definition available. + Details
Name: | all_CatastropheReinsuranceAgreementContractNumberofLayersSubjecttoReinstatement
Namespace Prefix: | all_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the period of catastrophe reinsurance agreement contract. + References No definition available. + Details
Name: | all_CatastropheReinsuranceAgreementContractTerm
Namespace Prefix: | all_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the retention amount of catastrophe reinsurance agreement contracts. + References No definition available. + Details
Name: | all_CatastropheReinsuranceAgreementContractsRetentionAmount
Namespace Prefix: | all_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the number of states covered under the reinsurance agreement. + References No definition available. + Details
Name: | all_NumberOfStatesCoveredUnderReinsuranceAgreement
Namespace Prefix: | all_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ReinsuranceRetentionPolicyLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_CededCreditRiskAxis=all_A20181ExcessCatastropheReinsuranceContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CededCreditRiskAxis=all_CatastropheReinsuranceFirstFiveLayersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CededCreditRiskAxis=all_CatastropheReinsuranceSixthLayerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CededCreditRiskAxis=all_CatastropheReinsuranceSeventhLayerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |