Label	Element	Value
Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Other Long-term Investments	us-gaap_OtherLongTermInvestments	$ 868,000,000
Other Long-term Investments	us-gaap_OtherLongTermInvestments	1,034,000,000
Available-for-sale Securities, Equity Securities	us-gaap_AvailableForSaleSecuritiesEquitySecurities	814,000,000
Available-for-sale Securities, Equity Securities	us-gaap_AvailableForSaleSecuritiesEquitySecurities	937,000,000
Investment Derivative Instruments Fair Value	cb_InvestmentDerivativeInstrumentsFairValue	31,000,000
Investment Derivative Instruments Fair Value	cb_InvestmentDerivativeInstrumentsFairValue	18,000,000
Liabilities, Fair Value Disclosure, Recurring	us-gaap_LiabilitiesFairValueDisclosureRecurring	626,000,000
Liabilities, Fair Value Disclosure, Recurring	us-gaap_LiabilitiesFairValueDisclosureRecurring	257,000,000
Assets, Fair Value Disclosure	us-gaap_AssetsFairValueDisclosure	87,804,000,000
Assets, Fair Value Disclosure	us-gaap_AssetsFairValueDisclosure	88,961,000,000
Other Derivative Instruments Fair Value	cb_OtherDerivativeInstrumentsFairValue	3,000,000
Other Derivative Instruments Fair Value	cb_OtherDerivativeInstrumentsFairValue	1,000,000
Securities Held as Collateral, at Fair Value	us-gaap_SecuritiesHeldAsCollateralAtFairValue	1,092,000,000
Securities Held as Collateral, at Fair Value	us-gaap_SecuritiesHeldAsCollateralAtFairValue	1,737,000,000
InvestmentDerivativeInstrumentsLiability	cb_InvestmentDerivativeInstrumentsLiability	54,000,000
InvestmentDerivativeInstrumentsLiability	cb_InvestmentDerivativeInstrumentsLiability	30,000,000
Other Derivative Instruments Fair Value Liability	cb_OtherDerivativeInstrumentsFairValueLiability	13,000,000
Other Derivative Instruments Fair Value Liability	cb_OtherDerivativeInstrumentsFairValueLiability	23,000,000
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	80,115,000,000
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	78,939,000,000
Separate Account Assets	us-gaap_SeparateAccountAssets	1,879,000,000
Separate Account Assets	us-gaap_SeparateAccountAssets	2,734,000,000
Other Short-term Investments	us-gaap_OtherShortTermInvestments	3,002,000,000
Other Short-term Investments	us-gaap_OtherShortTermInvestments	3,561,000,000
Corporate Debt Securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	24,149,000,000
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	23,996,000,000
Collateralized Mortgage Backed Securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	14,007,000,000
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	15,290,000,000
US States and Political Subdivisions Debt Securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	17,649,000,000
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	14,925,000,000
Foreign Government Debt Securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	21,440,000,000
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	21,030,000,000
US Treasury and Government [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	2,870,000,000
Available-for-sale Securities, Debt Securities	us-gaap_AvailableForSaleSecuritiesDebtSecurities	3,698,000,000
Guaranteed Minimum Income Benefit [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross	us-gaap_LiabilitiesForGuaranteesOnLongDurationContractsGuaranteedBenefitLiabilityGross	559,000,000
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross	us-gaap_LiabilitiesForGuaranteesOnLongDurationContractsGuaranteedBenefitLiabilityGross	$ 204,000,000