v2.4.0.8

Fair Value Measurements (Narrative) (Detail) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2014 | Sep. 30, 2013 | Sep. 30, 2014 | Sep. 30, 2013
Fair Value Measurements Of Financial Instruments [Line Items] |  |  |  |
Level 1 to Level 2 Transfers | $ 0 | $ 0 | $ 0 | $ 19
Level 2 to Level 1 Transfers | 0 | 0 | 0 | 0
Guaranteed Living Benefits, Net Income Impact From Model Refinement | $ 0 |  | $ (2) |
Redemption Notice Periods Lower Range [Member] |  |  |  |
Fair Value Measurements Of Financial Instruments [Line Items] |  |  |  |
Notice period for redemption for alternative investments investment funds, days |  |  | 5 days |
Redemption Notice Periods Upper Range [Member] |  |  |  |
Fair Value Measurements Of Financial Instruments [Line Items] |  |  |  |
Notice period for redemption for alternative investments investment funds, days |  |  | 120 days |

X
- Definition Amounts 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: | ace_FairValueAssetsLevel1ToLevel2TransfersAmounts
Namespace Prefix: | ace_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fair value assets Level 2 To Level 1 transfers amounts + References No definition available. + Details
Name: | ace_FairValueAssetsLevel2ToLevel1TransfersAmounts
Namespace Prefix: | ace_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | ace_FairValueMeasurementsOfFinancialInstrumentsLineItems
Namespace Prefix: | ace_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Guaranteed Living Benefits, Net Income Impact From Model Refinement + References No definition available. + Details
Name: | ace_GuaranteedLivingBenefitsNetIncomeImpactFromModelRefinement
Namespace Prefix: | ace_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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: | ace_NoticePeriodForRedemptionForAlternativeInvestmentsInvestmentFunds
Namespace Prefix: | ace_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration