ace:AccumulatedIncomeTaxExpenseBenefitMember Accumulated income tax (expense) benefit The tax effect on items included in other comprehensive income during the period. 0 ace:AvailableForSaleSecuritiesEquitySecuritiesCost Equity securities, at cost For an unclassified balance sheet, this item represents equity securities categorized neither as held-to-maturity nor trading. Equity securities represent ownership interests or the right to acquire ownership interests in corporations and other legal entities which ownership interest is represented by shares of common or preferred stock (which is not mandatorily redeemable or redeemable at the option of the holder), convertible securities, stock rights, or stock warrants. This disclosure reflects the value of the securities at cost. This item represents the cost of the equity security adjusted for other than temporary impairments, where applicable. 2 ace:ChangeInUnearnedPremiumNet Change in unearned premiums Change during the period in the unearned portion of gross premiums written (direct and assumed) and ceded premiums written, excluding the portion amortized into income. 4 ace:CommitmentsContingenciesGuaranteesDisclosureTextBlock Commitments, contingencies and guarantees Includes disclosure of commitments and contingencies. This element may be used as a single block of text to encapsulate the entire disclosure including data and tables. Provides pertinent information about each guarantee obligation, or each group of similar guarantee obligations, including (a) the nature of the guarantee, including its term, how it arose, and the events or circumstances that would require the guarantor to perform under the guarantee; (b) the maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee; (c) the current carrying amount of the liability, if any, for the guarantor's obligations under the guarantee; and (d) the nature of any recourse provisions under the guarantee, and any assets held either as collateral or by third parties, and any relevant related party disclosure. Excludes disclosures about product warranties. 1 ace:CommonShareParValueAxis Common share par value axis 0 ace:CommonShareParValueTable Common share par value in CHF 0 ace:CommonSharesParValueAbstract Common shares par value table 0 ace:CommonStockIssuedEmployeeStockTrustMember Common stock issued to employee trust Common Shares issued to employee trust 0 ace:CommonStockParValueMember Common shares par value 0 ace:ComprehensiveIncomeLoss Comprehensive income (loss) Net income (loss) plus other comprehensive income (loss). 4 ace:ConsolidatedBalanceSheetAssetsParentheticalDisclosures Consolidated balance sheets - assets - parenthetical disclosures 0 ace:ConsolidatedBalanceSheetEquityParentheticalDisclosures Consolidated balance sheets - equity - parenthetical disclosures 0 ace:ConsolidatedBalanceSheetsParentheticalDisclosures Consolidated balance sheets parenthetical disclosures 0 ace:ConsolidatedStatementsOfCashFlowsParentheticals Consolidated statements of cash flows parenthetical disclosures 0 ace:CumulativeEffectPartialAdoptionFAS157 Effect of partial adoption of fair value measurements standard The effect on the opening balance of the partial adoption of FAS 157: Fair Value Measurements 4 ace:DebtOutstandingSubsidiariesDisclosuresTextBlock Information provided in connection with outstanding debt of subsidiaries Disclosures of condensed financial information for the parent guarantor and subsidiary issuer in relation to debt of the subsidiary issuer which is fully guaranteed by the parent guarantor 1 ace:DividendsDeclaredCommonStockParValueReduction Dividends declared on Common Shares - par value reduction Dividends declared to common shareholders from the reduction in the par value of the common shares. 2 ace:EffectOfAdoptionOfFSPFAS1152AndFAS1242 Effect of adoption of OTTI standard Effect of the adoption of FSP FAS 115-2 - recognition and presentation of other-than-temporary impairments 4 ace:GoodwillAndIntangibles Goodwill and other intangible assets Goodwill - the excess of the cost of an acquired entity over the net of the amounts assigned to assets acquired and liabilities assumed. Intangible Assets - assets (not including financial assets) that lack physical substance (some, but not all, of which are subject to amortization). 2 ace:GrossPremiumsWrittenDirectAndAssumed Gross premiums written Total consideration paid and payable by direct and assumed policyholders for insurance contracts sold by the Entity during the period. 4 ace:IncreaseDecreaseInAccountsPayableAccruedLiabilitiesOtherLiabilities Accounts payable, accrued expenses, and other liabilities (cash flow) The change, in accounts payable, accrued liabilities and other liabilities recorded on the balance sheet, is needed to adjust net income to arrive at net cash flows provided by (used in) operations. 2 ace:IncreaseDecreaseInInsuranceAndReinsuranceBalancesPayable Insurance and reinsurance balances payable (cash flow) The change, in insurance and reinsurance balances payable recorded on the balance sheet, is needed to adjust net income to arrive at net cash flows provided by (used in) operations. 2 ace:IncreaseDecreaseInInsuranceAndReinsuranceBalancesReceivable Insurance and reinsurance balances receivable (cash flow) The change, in insurance and reinsurance balances receivable recorded on the balance sheet, is needed to adjust net income to arrive at net cash flows provided by (used in) operations. 2 ace:IncreaseDecreaseInReinsuranceRecoverableFuturePolicyBenefits Reinsurance recoverable on policy benefits (cash flow) The change, in reinsurance recoverable relating to future policy benefits recorded on the balance sheet, is needed to adjust net income to arrive at net cash flows provided by (used in) operations. 2 ace:IncreaseDecreaseInReinsuranceRecoverableLossesAndLossExpenses Reinsurance recoverable on losses and loss expenses (cash flow) The change, in reinsurance recoverable relating to loss and loss expenses recorded in the income statement, is needed to adjust net income to arrive at net cash flows provided by (used in) operations. 2 ace:InvestmentsDisclosureTextBlock Investments Includes disclosures relating to the balance sheet and income statement components of the investment balances (fixed maturities available for sale, fixed maturities held to maturity, equity securities, short-term investments, investments in partially-owned insurance companies and other investments). 1 ace:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVenturesAtCost Investments in partially-owned insurance companies, at cost Total investments at cost in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable form a party that is affiliated with the reporting entity by means of direct or indirect ownership. 2 ace:MovementInCommonSharesIssuedToEmployeeTrust Decrease in common shares (Employee Trust) Movement in the value of the common shares issued to employee trust. 2 ace:NetIncomeBeforeTax Net income before tax Net Income before tax 4 ace:NetOtherThanTemporaryImpairmentsRecognizedInNetIncome Net OTTI losses recognized in income Other-than-temporary impairment losses net of the portion of which is recognized in income in accordance with FSP FAS 115-2 and FAS 124-2 4 ace:NetRealizedGainsLosses Net realized gains (losses) The net realized gains or losses on investments, derivative instruments, and foreign exchange recognized during the period. 4 ace:NetRealizedGainsLossesAbstract Net realized gains (losses): 0 ace:NetRealizedGainsLossesExcludingOTTI Net realized gains (losses) excluding OTTI losses The net realized gains or losses on investments, derivative instruments and foreign exchange recognized during the period excluding other-than-temporary impairments 4 ace:NotesToConsolidatedFinancialStatements Notes to the Consolidated Financial Statements 0 ace:OtherComprehensiveIncomeAdjustedForAdoptionOfAccountingPrinciple Balance - beginning of period, adjusted for effect of adoption of new accounting principle Opening balance of accumulated other comprehensive income adjusted for the adoption of new accounting principle(s). 4 ace:OtherComprehensiveIncomeLossSubtotal Subtotal Other Comprehensive Income Loss subtotal of unrealized depreciation/appreciation and reclassification adjustment for net realized gains/losses included in net income 4 ace:OtherComprehensiveIncomeOtherThanTemporaryImpairmentsFixedMaturitiesAFS Other-than-temporary impairments - fixed maturities AFS The amount of other-than-temporary impairments for fixed maturities available for sale that are reflected in comprehensive income in accordance with FSP FAS 115-2 and FAS 124-2 0 ace:OtherComprehensiveIncomeOtherThanTemporaryImpairmentsFixedMaturitiesHTM Other-than-temporary impairments - fixed maturities HTM The amount of other-than-temporary impairments for fixed maturities held to maturity that are reflected in comprehensive income in accordance with FSP FAS 115-2 and FAS 124-2 0 ace:OtherInvestmentsAndSecurities Other investments, at cost Includes other investments and securities reflected at cost as of the balance sheet date. 2 ace:OtherShortTermInvestmentsAtAmortizedCost Short-term investments, at amortized cost Other investments, at amortized cost, 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. 2 ace:ParValueReductionCommonShares Par value reduction on Common Shares The cash outflow to common shareholders from the reduction in the par value of the common shares. 0 ace:PaymentsToAcquireTBAMortgageBackedSecurities Purchases of to be announced mortgage-backed securities The cash outflow for the purchase of TBA Mortgage-backed securities secured by and repaid from underlying mortgages, which were designated as available for sale when acquired. 2 ace:PortionOtherThanTemporaryLossesInAccumulatedOtherComprehensiveIncome Portion of OTTI losses recognized in other comprehensive income The portion of other-than-temporary losses which is recognized in other comprehensive income 4 ace:ProceedsFromRepaymentsOfShortTermBorrowings Net (repayment of) proceeds from short-term debt The net cash inflow (outflow) for borrowing having terms of repayment within one year. 2 ace:ProceedsFromSalesTBAMortgageBackedSecurities Sales of to be announced mortgage-backed securities The cash inflow associated with the sale of TBA mortgage-backed securities (AFS). 2 ace:ReinsuranceRecoverableFuturePolicyBenefits Reinsurance recoverable on policy benefits The known and estimated amount recoverable as of the balance sheet date from reinsurers for claims paid or incurred by the ceding insurer and associated policy benefits net of any related valuation allowance. 2 ace:ReinsuranceRecoverableLossesAndLossExpenses Reinsurance recoverable on losses and loss expenses The known and estimated amount recoverable as of the balance sheet date from reinsurers for claims paid or incurred by the ceding insurer and associated claims settlement expenses, including estimated amounts for claims incurred but not reported net of any related valuation allowance. 2 ace:ShortTermDebt Short-term debt Reflects the total carrying amount as of the balance sheet date of debt which matures in less than one year. 2 ace:SubsequentEventsDisclosuresTextBlock Subsequent events Disclosure of a significant event or transaction that occurred between the balance sheet date and the date the financial statements are issued. 1 ace:TreasuryStockIssuedNetOfSharesRedeemedUnderEmployeeShareBasedCompensationPlans Common shares issued in treasury, net of net shares redeemed under employee-based compensation plans Common shares issued in Treasury net of shares redeemed under employee share-based compensation plans 2 ace:TrustPreferredSecurities Trust preferred securities Preferred securities that embody an unconditional obligation requiring the issuer to redeem the securities by transferring the assets at a specified or determinable date (or dates) or upon an event that is certain to occur, that are issued by a consolidated trust to outside investors where the trust uses the proceeds of the issuance of those securities to purchase, from the financial institution that established the trust, an equivalent amount of junior subordinated debentures or other loans having stated maturities. The trust-preferred securities must be redeemed upon maturity of the debentures or other loans. 2