XML 50 R38.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Investments (Narrative) (Detail) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2017 USD ($) Security | Jun. 30, 2016 USD ($) | Jun. 30, 2017 USD ($) Security | Jun. 30, 2016 USD ($) | Dec. 31, 2016 USD ($)
Investment [Line Items] |  |  |  |  |
Net unrealized depreciation included in OCI | $ 3 | $ 21 | $ 3 | $ 44 |
Unrealized appreciation(depreciation) portion of AOCI with OTTI included in AOCI | $ 7 |  | $ 7 |  | $ 10
Percentage of mortgage-backed securities represented by investments in US government agency bonds | 81.00% |  | 81.00% |  | 81.00%
Total number of fixed maturities | Security | 30,953 |  | 30,953 |  |
Number of equity securities in an unrealized loss position | Security | 67 |  | 67 |  |
Total number of equity securities | Security | 320 |  | 320 |  |
Largest single unrealized loss in the equity securities | $ 1 |  | $ 1 |  |
Restricted assets in fixed maturities and short-term investments | 21,200 |  | 21,200 |  | $ 20,100
Restricted assets in cash | $ 122 |  | $ 122 |  | $ 103
Moodys Historical Mean Recovery Rate |  |  | 42.00% |  |
Company Assumed Recovery Rate |  |  | 32.00% |  |
Number of fixed maturities in an unrealized loss position | Security | 7,924 |  | 7,924 |  |
Largest single unrealized loss in the fixed maturities | $ 5 |  | $ 5 |  |
Corporate [Member] |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Credit losses recognized in net income | 1 | 7 | 2 | 24 |
Collateralized Mortgage Backed Securities [Member] |  |  |  |  |
Investment [Line Items] |  |  |  |  |
Credit losses recognized in net income | $ 0 | $ 0 | $ 0 | $ 0 |

X
- Definition AOCI Portion Attributable to change of FV of investments with OTTI + References No definition available. + Details
Name: | cb_AOCIPortionAttributabletochangeofFVofinvestmentswithOTTI
Namespace Prefix: | cb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Company assumed recovery rate. + References No definition available. + Details
Name: | cb_CompanyAssumedRecoveryRate
Namespace Prefix: | cb_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Equity Securities In Unrealized Loss Position Number + References No definition available. + Details
Name: | cb_EquitySecuritiesInUnrealizedLossPositionNumber
Namespace Prefix: | cb_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Equity Securities Largest Single Unrealized Loss + References No definition available. + Details
Name: | cb_EquitySecuritiesLargestSingleUnrealizedLoss
Namespace Prefix: | cb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Equity Securities Total Number + References No definition available. + Details
Name: | cb_EquitySecuritiesTotalNumber
Namespace Prefix: | cb_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of fixed maturities in an unrealized loss position. + References No definition available. + Details
Name: | cb_FixedMaturitiesInUnrealizedLossPositionNumber
Namespace Prefix: | cb_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Largest single unrealized loss in the fixed maturities. + References No definition available. + Details
Name: | cb_FixedMaturitiesLargestSingleUnrealizedLoss
Namespace Prefix: | cb_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Total number of fixed maturities. + References No definition available. + Details
Name: | cb_FixedMaturitiesTotalNumber
Namespace Prefix: | cb_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Moodys historical mean recovery rate. + References No definition available. + Details
Name: | cb_MoodysHistoricalMeanRecoveryRate
Namespace Prefix: | cb_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of mortgage-backed securities represented by investments in US Government Agency bonds. + References No definition available. + Details
Name: | cb_MortgageBackedSecuritiesPercentageUnitedStatesGovernmentAgencyBonds
Namespace Prefix: | cb_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Net unrealized appreciation included in other comprehensive income relating to securities upon which a credit impairment was recorded. + References No definition available. + Details
Name: | cb_NetUnrealizedAppreciationIncludedInOtherComprehensiveIncome
Namespace Prefix: | cb_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent reporting 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 Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 12 -Sentence Column A + Details
Name: | invest_InvestmentLineItems
Namespace Prefix: | invest_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of increase (decrease) in the cumulative amount of credit losses recognized in earnings related to debt securities held for which a portion of an other than temporary impairment (OTTI) was recognized in other comprehensive income (loss). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 8B -URI http://asc.fasb.org/extlink&oid=73527792&loc=SL6284393-111563 + Details
Name: | us-gaap_OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsPeriodIncreaseDecrease
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | duration

X
- Definition The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. This element is for unclassified presentations; for classified presentations there is a separate and distinct element. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_RestrictedCashAndCashEquivalents
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Investments which are not defined as or included in marketable (debt, equity, or other) securities whose use is restricted in whole or in part, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet. + References No definition available. + Details
Name: | us-gaap_RestrictedInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CorporateDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_MortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |