XML 58 R47.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Fair value measurements Fair Value Measurements (narrative) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2017 | Sep. 30, 2016
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |  |  |
Fair Value, Level 1 to Level 2 transfers, Amount | $ 0 | $ 0 | $ 0 | $ 0
Fair Value, Level 2 to Level 1 Transfers, Amount | 0 | $ 0 | $ 0 | $ 0
Realized Gain Losses As A Result of Annuitization Changes | $ 94 |  |  |
Minimum [Member] |  |  |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |  |  |
Notice Period For Redemption For Alternative Investments Investment Funds |  |  | 5 days |
Maximum [Member] |  |  |  |
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items] |  |  |  |
Notice Period For Redemption For Alternative Investments Investment Funds |  |  | 120 days |

X
- Definition Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2. + References No definition available. + Details
Name: | cb_FairValueLevel1toLevel2transfersAmount
Namespace Prefix: | cb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1. + References No definition available. + Details
Name: | cb_FairValueLevel2toLevel1TransfersAmount
Namespace Prefix: | cb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Notice period in days for redemption of investment funds alternative investments (employ various investment strategies such as long/short equity and arbitrage/distressed.) + References No definition available. + Details
Name: | cb_NoticePeriodForRedemptionForAlternativeInvestmentsInvestmentFunds
Namespace Prefix: | cb_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Realized Gain Losses As A Result of Annuitization Changes + References No definition available. + Details
Name: | cb_RealizedGainLossesAsAResultofAnnuitizationChanges
Namespace Prefix: | cb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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_FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |