2.2.0.25falsefalse0150 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)truefalseIn Millionsfalse1falsefalseUSDfalsefalse1/1/2011 - 3/31/2011 USD ($) USD ($) / shares $Jan-01-2011_Mar-31-2011http://www.sec.gov/CIK0001267395duration2011-01-01T00:00:002011-03-31T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0USDEPSDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0USDUSD$2falsefalseUSDfalsefalse1/1/2010 - 3/31/2010 USD ($) USD ($) / shares $ThreeMonthsEnded_31Mar2010http://www.sec.gov/CIK0001267395duration2010-01-01T00:00:002010-03-31T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDEPSDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$3true0us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstractus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringThe net cash from (used in) all of the entity's operating activities, including those of discontinued operations, of the reporting entity. 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http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 falsefalseFunds withheld22false0us-gaap_IncreaseDecreaseInDeferredIncomeTaxesus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse4000000.4falsefalsefalsefalsefalse2truefalsefalse12000001.2falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net change during the reporting period in the account that represents the temporary difference that results from income (loss) that is recognized for accounting purposes but not for tax purposes and vice versa.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 falsefalseDeferred taxes23false0us-gaap_IncreaseDecreaseInAccruedIncomeTaxesPayableus-gaaptruedebitdurationNo definition 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Operating activity cash flows include transactions, adjustments, and changes in value that are not defined as investing or financing activities.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 26 truefalseNet cash provided by operating activities28true0us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstractus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseCash flows provided by/(used in) investing activities:29false0us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse-874500000-874.5falsefalsefalsefalsefalse2truefalsefalse-604800000-604.8falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash outflow to acquire debt and equity securities not classified as either held-to-maturity securities or trading securities which would be classified as available-for-sale securities and reported at fair value, with unrealized gains and losses excluded from earnings and reported in a separate component of shareholders' equity.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 17 -Subparagraph b Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 18 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 17 -Subparagraph a falsefalse(Purchases) of fixed income maturities30false0us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesEquityus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse-171100000-171.1falsefalsefalsefalsefalse2truefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash outflow to acquire equity securities classified as available-for-sale securities, because they are not classified as trading securities.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 17 -Subparagraph b falsefalse(Purchases) of equity securities31false0us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebtus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse751500000751.5falsefalsefalsefalsefalse2truefalsefalse544800000544.8falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash inflow associated with the sale of debt securities classified as available-for-sale securities.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 16 -Subparagraph a falsefalseProceeds from sales and maturities of fixed income maturities32false0us-gaap_PaymentsForProceedsFromShortTermInvestmentsus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse106500000106.5falsefalsefalsefalsefalse2truefalsefalse132600000132.6falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net amount paid (received) by the reporting entity through acquisition (sale/maturities) of short-term investments with an original maturity that is three months or less which qualify for treatment as an investing activity based on management's intention and intended by management to be liquidated, if necessary, within the current operating cycle. Includes cash flows from securities classified as trading securities that were acquired for reasons other than sale in the short-term.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 13 falsefalseNet sales/(purchases) of short-term investments33false0us-gaap_ProceedsFromSaleAndCollectionOfReceivablesus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse-22200000-22.2falsefalsefalsefalsefalse2truefalsefalse57000005.7falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash inflow associated with the proceeds from sale and collection of receivables during the period.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name 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available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegatedtotal1truefalsefalse-5000000-5.0falsefalsefalsefalsefalse2truefalsefalse-800000-0.8falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash outflow for acquisition of machinery and equipment.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 17 -Subparagraph c truefalse(Purchase) of equipment36false0us-gaap_NetCashProvidedByUsedInInvestingActivitiesus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse-214800000-214.8falsefalsefalsefalsefalse2truefalsefalse7370000073.7falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net cash inflow (outflow) from investing activity.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 26 truefalseNet cash (used in)/provided by investing activities37true0us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstractus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseCash flows used in financing activities:38false0us-gaap_ProceedsFromIssuanceOfCommonStockus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse5000000.5falsefalsefalsefalsefalse2truefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash inflow from the additional capital contribution to the entity.Reference 1: 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of Financial Accounting Standard (FAS) -Number 95 -Paragraph 20 -Subparagraph a falsefalseOrdinary shares repurchased40false0us-gaap_ProceedsFromMinorityShareholdersus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse-200000-0.2falsefalsefalsefalsefalse2truefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash inflow contributed by noncontrolled interest that purchase additional shares or otherwise increase their ownership stake in a subsidiary of the entity.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 19 -Subparagraph a falsefalseProportion of net loss due to non-controlling interest41false0us-gaap_PaymentsOfOrdinaryDividendsus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegated1truefalsefalse-10600000-10.6falsefalsefalsefalsefalse2truefalsefalse-11800000-11.8falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash outflow from distribution of an entity's earnings to common and preferred stockholders, including minority shareholders. This element excludes special dividends, which are included in a separate element for capital distributions.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 20 -Subparagraph a falsefalseDividends paid on ordinary shares42false0us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStockus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsetruenegatedtotal1truefalsefalse-5700000-5.7falsefalsefalsefalsefalse2truefalsefalse-5700000-5.7falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe cash outflow for the return on capital for preferred shareholders.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 20 -Subparagraph a truefalseDividends paid on preference shares43false0us-gaap_NetCashProvidedByUsedInFinancingActivitiesus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse-17700000-17.7falsefalsefalsefalsefalse2truefalsefalse-217500000-217.5falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net cash inflow (outflow) from financing activity for the period.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 26 truefalseNet cash (used in) financing activities44false0us-gaap_EffectOfExchangeRateOnCashAndCashEquivalentsus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse1540000015.4falsefalsefalsefalsefalse2truefalsefalse-6000000-6.0falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe effect of exchange rate changes on cash balances held in foreign currencies.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 25 truefalseEffect of exchange rate movements on cash and cash equivalents45false0us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1truefalsefalse-62200000-62.2falsefalsefalsefalsefalse2truefalsefalse-47000000-47.0falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net change between the beginning and ending balance of cash and cash equivalents.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 26 falsefalse(Decrease) in cash and cash equivalents46false0us-gaap_CashAndCashEquivalentsAtCarryingValueus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsetruefalsefalseperiodstartlabel1truefalsefalse11791000001179.1falsefalsefalsefalsefalse2truefalsefalse748400000748.4falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncludes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Entity may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Compensating balance arrangements that do not legally restrict the withdrawal or usage of cash amounts may be reported as Cash and Cash Equivalents, while legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits should not be reported as cash and cash equivalents.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 7, 26 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 8, 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 7 -Footnote 1 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 1 -Article 5 falsefalseCash and cash equivalents at beginning of period47false0us-gaap_CashAndCashEquivalentsAtCarryingValueus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsetruefalseperiodendlabel1truefalsefalse11169000001116.9falsefalsefalsefalsefalse2truefalsefalse701400000701.4falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryIncludes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Entity may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Compensating balance arrangements that do not legally restrict the withdrawal or usage of cash amounts may be reported as Cash and Cash Equivalents, while legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits should not be reported as cash and cash equivalents.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 7, 26 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 8, 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 7 -Footnote 1 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 1 -Article 5 falsefalseCash and cash equivalents at end of period48true0ahl_SupplementalDisclosureOfCashFlowsInformationAbstractahlfalsenadurationSupplemental Disclosure of Cash Flow Informationfalsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringSupplemental Disclosure of Cash Flow InformationfalsefalseSupplemental disclosure of cash flow information:49false0us-gaap_IncomeTaxesPaidus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse4000000.4falsefalsefalsefalsefalse2truefalsefalse1880000018.8falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 29 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 27 -Subparagraph f falsefalseCash paid during the period for income tax50false0us-gaap_InterestPaidus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse75000007.5falsetruefalsefalsefalse2truefalsefalse75000007.5falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe amount of cash paid during the current period for interest owed on money borrowed; includes amount of interest capitalizedReference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 29 falsefalseCash paid during the period for interest on long-term debt248CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (USD $)HundredThousandsUnKnownUnKnownUnKnownfalsetrue