XML 47 R90.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Unpaid losses and loss expenses Unpaid losses and loss expenses (Details) (Supplementary PPD) (Details) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 USD ($)
North America Commercial P&C Insurance - Workers' Compensation [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | $ (288)
North America Commercial P&C Insurance - Workers' Compensation [Member] | prior to 2010 [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (93)
North America Commercial P&C Insurance - Liability [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (273)
North America Commercial P&C Insurance - Liability [Member] | prior to 2010 [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (49)
North America Commercial P&C Insurance - Other Casualty [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (36)
North America Commercial P&C Insurance - Other Casualty [Member] | prior to 2010 [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | 5
North America Commercial P&C Insurance - Non-Casualty [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | 32
North America Commercial P&C Insurance - Non-Casualty [Member] | prior to 2010 [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (6)
North America Personal P&C Insurance [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (86)
North America Personal P&C Insurance [Member] | prior to 2010 [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (1)
Overseas General Insurance - Casualty [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (61)
Overseas General Insurance - Casualty [Member] | prior to 2010 [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (18)
Overseas General Insurance - Non-Casualty [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | 1
Overseas General Insurance - Non-Casualty [Member] | prior to 2010 [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | 1
Global Reinsurance - Casualty [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (58)
Global Reinsurance - Casualty [Member] | prior to 2010 [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | (50)
Global Reinsurance - Non-Casualty [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | 30
Global Reinsurance - Non-Casualty [Member] | prior to 2010 [Member] |
Supplementary PPD [Line Items] |
Short-Duration PPD | $ (4)

X
- Definition short-duration PPD + References No definition available. + Details
Name: | cb_ShortdurationPPD
Namespace Prefix: | cb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition [Line Items] for Supplementary PPD [Table] + References No definition available. + Details
Name: | cb_SupplementaryPPDLineItems
Namespace Prefix: | cb_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cb_NorthAmericaWorkersCompensationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShortdurationInsuranceContractsAccidentYearAxis=cb_Priorto2010Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cb_NorthAmericaGeneralLiabilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cb_NorthAmericaOtherCasualtyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cb_NorthAmericaNonCasualtyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cb_NorthAmericaPersonalPCInsuranceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cb_OverseasGeneralCasualtyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cb_OverseasGeneralNonCasualtyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cb_GlobalReinsuranceCasualtyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=cb_GlobalReinsuranceNonCasualtyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |