v3.2.0.727

Fair Value Measurements (Financial Instruments Measured At Fair Value On Recurring Basis) (Detail) - USD ($) $ in Millions | 6 Months Ended |
--- | --- | ---
Jun. 30, 2015 | Dec. 31, 2014
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Document Period End Date |  | Jun. 30, 2015 |  |
Available for sale, Fair Value |  | $ 48,701 | $ 49,395 |
Equity securities, at fair value |  | 498 | 510 |
Short-term investments |  | 2,062 | 2,322 |
Other investments |  | 3,328 | 3,346 |
Securities lending collateral |  | 1,080 | 1,330 |
Investment derivative instruments, assets |  | 16 | 18 |
Other derivative instruments, assets |  | 23 | 2 |
Separate account assets |  | 1,651 | 1,490 |
Total assets measured at fair value |  | 57,359 | 58,413 |
Investment derivative instruments, liabilities |  | 15 | 36 |
Other derivative instruments, liability |  | 3 | 25 |
GLB |  | 347 | 406 | [1]
Total liabilities measured at fair value |  | 365 | 467 |
Fair Value, Inputs, Level 1 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 1,741 | 1,680 |
Equity securities, at fair value |  | 483 | 492 |
Short-term investments |  | 1,108 | 1,183 |
Other investments |  | 370 | 370 |
Securities lending collateral |  | 0 | 0 |
Investment derivative instruments, assets |  | 16 | 18 |
Other derivative instruments, assets |  | 23 | 0 |
Separate account assets |  | 1,567 | 1,400 |
Total assets measured at fair value |  | 5,308 | 5,143 |
Investment derivative instruments, liabilities |  | 15 | 36 |
Other derivative instruments, liability |  | 0 | 21 |
GLB | [1] | 0 | 0 |
Total liabilities measured at fair value |  | 15 | 57 |
Fair Value, Inputs, Level 2 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 46,682 | 47,491 |
Equity securities, at fair value |  | 13 | 16 |
Short-term investments |  | 954 | 1,139 |
Other investments |  | 279 | 257 |
Securities lending collateral |  | 1,080 | 1,330 |
Investment derivative instruments, assets |  | 0 | 0 |
Other derivative instruments, assets |  | 0 | 2 |
Separate account assets |  | 84 | 90 |
Total assets measured at fair value |  | 49,092 | 50,325 |
Investment derivative instruments, liabilities |  | 0 | 0 |
Other derivative instruments, liability |  | 0 | 0 |
GLB | [1] | 0 | 0 |
Total liabilities measured at fair value |  | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 278 | 224 |
Equity securities, at fair value |  | 2 | 2 |
Short-term investments |  | 0 | 0 |
Other investments |  | 2,679 | 2,719 |
Securities lending collateral |  | 0 | 0 |
Investment derivative instruments, assets |  | 0 | 0 |
Other derivative instruments, assets |  | 0 | 0 |
Separate account assets |  | 0 | 0 |
Total assets measured at fair value |  | 2,959 | 2,945 |
Investment derivative instruments, liabilities |  | 0 | 0 |
Other derivative instruments, liability |  | 3 | 4 |
GLB | [1] | 347 | 406 |
Total liabilities measured at fair value |  | 350 | 410 |
U.S. Treasury And Agency [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 2,805 | 2,820 |
U.S. Treasury And Agency [Member] | Fair Value, Inputs, Level 1 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 1,741 | 1,680 |
U.S. Treasury And Agency [Member] | Fair Value, Inputs, Level 2 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 1,064 | 1,140 |
U.S. Treasury And Agency [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 0 | 0 |
Foreign [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 15,156 | 15,242 |
Foreign [Member] | Fair Value, Inputs, Level 1 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 0 | 0 |
Foreign [Member] | Fair Value, Inputs, Level 2 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 15,100 | 15,220 |
Foreign [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 56 | 22 |
Corporate Securities [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 16,878 | 17,431 |
Corporate Securities [Member] | Fair Value, Inputs, Level 1 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 0 | 0 |
Corporate Securities [Member] | Fair Value, Inputs, Level 2 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 16,711 | 17,244 |
Corporate Securities [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 167 | 187 |
Collateralized Mortgage Backed Securities [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 10,784 | 10,286 |
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 0 | 0 |
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 10,729 | 10,271 |
Collateralized Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 55 | 15 |
States, Municipalities, And Political Subdivisions [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 3,078 | 3,616 |
States, Municipalities, And Political Subdivisions [Member] | Fair Value, Inputs, Level 1 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 0 | 0 |
States, Municipalities, And Political Subdivisions [Member] | Fair Value, Inputs, Level 2 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | 3,078 | 3,616 |
States, Municipalities, And Political Subdivisions [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value |  | $ 0 | $ 0 |
[1] | Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value. Excluded from the table above is the portion of the GLB liability classified as Future policy benefits in the consolidated balance sheets. Refer to Note 5 for additional information.

X
- Definition Total assets reflected at fair value + References No definition available. + Details
Name: | ace_AssetsFairValue
Namespace Prefix: | ace_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] + References No definition available. + Details
Name: | ace_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisLineItems
Namespace Prefix: | ace_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition GMIB - The fair value of the benefit in long-duration contracts to provide a guaranteed minimum amount available for annuitization after a specified period, which is in addition to a guaranteed minimum annuity rate. GMAB - The guaranteed account value floor that is available to a contractor policy holder in cash + References No definition available. + Details
Name: | ace_GuaranteedLivingBenefitsLiabilities
Namespace Prefix: | ace_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The fair value for actively traded investment derivative instruments including futures, options, and exchange traded forward contracts reflected as an asset. + References No definition available. + Details
Name: | ace_InvestmentDerivativeInstrumentsFairValue
Namespace Prefix: | ace_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Investment Derivative Instruments Liability + References No definition available. + Details
Name: | ace_InvestmentDerivativeInstrumentsLiability
Namespace Prefix: | ace_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The fair value of all other derivative instruments held by the Company. + References No definition available. + Details
Name: | ace_OtherDerivativeInstrumentsFairValue
Namespace Prefix: | ace_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Other Derivative Instruments Fair Value Liability + References No definition available. + Details
Name: | ace_OtherDerivativeInstrumentsFairValueLiability
Namespace Prefix: | ace_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Separate account assets fair value + References No definition available. + Details
Name: | ace_SeparateAccountAssetsFairValue
Namespace Prefix: | ace_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The end date of the period reflected on the cover page if a periodic report. For all other reports and registration statements containing historical data, it is the date up through which that historical data is presented. If there is no historical data in the report, use the filing date. The format of the date is CCYY-MM-DD. + References No definition available. + Details
Name: | dei_DocumentPeriodEndDate
Namespace Prefix: | dei_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of debt securities categorized neither as held-to-maturity nor trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49167202&loc=d3e26610-111562 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 2 -Subparagraph (b)-(g) -URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803 + Details
Name: | us-gaap_AvailableForSaleSecuritiesDebtSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of equity securities categorized neither as held-to-maturity nor as trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49167202&loc=d3e26610-111562 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6957658&loc=d3e62557-112803 + Details
Name: | us-gaap_AvailableForSaleSecuritiesEquitySecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Aggregation of the liabilities reported on the balance sheet measured at fair value on a recurring basis by the entity. + References No definition available. + Details
Name: | us-gaap_LiabilitiesFairValueDisclosureRecurring
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Other long-term investments not otherwise specified in the taxonomy, not including investments in marketable securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1(f)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_OtherLongTermInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Other investments not otherwise specified in the taxonomy that will be realized in a short period of time, usually less than one year or the normal operating cycle, whichever is longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.5) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.8) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.1(g)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
Name: | us-gaap_OtherShortTermInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The carrying amount (fair value) as of the balance sheet date of securities held that had been pledged by counterparties under financing and lending arrangements, pursuant to which the entity has the right by agreement or custom to sell or re-pledge such securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5086-111524 + Details
Name: | us-gaap_SecuritiesHeldAsCollateralAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ace_FixedMaturitiesAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ace_FixedMaturitiesAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

X
- Details
Name: | ace_FixedMaturitiesAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |