XML 118 R91.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Unpaid losses and loss expenses Unpaid losses and loss expenses (Details) (Supplementary PPD) (Details) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2017 USD ($)
North America Commercial P&C Insurance - Workers' Compensation [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | $ (108)
North America Commercial P&C Insurance - Workers' Compensation [Member] | prior to 2008 [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | (35)
North America Commercial P&C Insurance - Liability [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | (434)
North America Commercial P&C Insurance - Liability [Member] | prior to 2008 [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | (154)
North America Commercial P&C Insurance - Other Casualty [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | 0
North America Commercial P&C Insurance - Other Casualty [Member] | prior to 2008 [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | 14
North America Commercial P&C Insurance - Non-Casualty [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | (188)
North America Commercial P&C Insurance - Non-Casualty [Member] | prior to 2008 [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | 0
North America Personal P&C Insurance [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | 76
North America Personal P&C Insurance [Member] | prior to 2008 [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | (10)
Overseas General Insurance - Casualty [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | (68)
Overseas General Insurance - Casualty [Member] | prior to 2008 [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | (13)
Overseas General Insurance - Non-Casualty [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | (141)
Overseas General Insurance - Non-Casualty [Member] | prior to 2008 [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | (3)
Global Reinsurance - Casualty [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | (72)
Global Reinsurance - Casualty [Member] | prior to 2008 [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | (60)
Global Reinsurance - Non-Casualty [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | 16
Global Reinsurance - Non-Casualty [Member] | prior to 2008 [Member] |
Supplementary PPD [Line Items] |
short-duration PPD | $ 0

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_Priorto2008Member
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_GlobalReinsuranceNonPropertyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |