v2.4.0.6

SEGMENT INFORMATION (DETAILS) (USD $) In Thousands, unless otherwise specified | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2011 | Sep. 30, 2011 | Jun. 30, 2011 | Mar. 31, 2011 | Dec. 31, 2010 | Sep. 30, 2010 | Jun. 30, 2010 | Mar. 31, 2010 | Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2009
Segment Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of reportable segments | 2 |  |  |  |  |  |  |  | 2 |  |
Gross premiums written |  |  |  |  |  |  |  |  | $ 4,096,153 | $ 3,750,536 | $ 3,587,295
Net premiums written |  |  |  |  |  |  |  |  | 3,419,434 | 3,147,540 | 2,816,429
Net premiums earned | 846,753 | 839,992 | 840,014 | 788,201 | 757,318 | 758,873 | 735,027 | 696,192 | 3,314,961 | 2,947,410 | 2,791,764
Other insurance related income (loss) |  |  |  |  |  |  |  |  | 2,396 | 2,073 | (129,681)
Net losses and loss expenses |  |  |  |  |  |  |  |  | (2,675,052) | (1,677,132) | (1,423,872)
Acquisition costs |  |  |  |  |  |  |  |  | (587,469) | (488,712) | (420,495)
General and administrative expenses |  |  |  |  |  |  |  |  | (382,062) | (374,436) | (293,081)
Underwriting income (loss) | 15,076 | 90,029 | 28,974 | (461,305) | 132,546 | 127,376 | 120,836 | 28,446 | (327,226) | 409,203 | 524,635
Corporate expenses |  |  |  |  |  |  |  |  | (77,089) | (75,449) | (77,076)
Net investment income | 102,362 | 49,396 | 100,018 | 110,655 | 107,889 | 111,800 | 82,584 | 104,619 | 362,430 | 406,892 | 464,478
Net realized investment gains (losses) | (3,738) | 57,557 | 37,477 | 30,144 | 77,772 | 76,531 | 24,619 | 16,176 | 121,439 | 195,098 | (311,584)
Foreign exchange (losses) gains |  |  |  |  |  |  |  |  | 44,582 | 15,535 | (28,561)
Interest expense and financing costs |  |  |  |  |  |  |  |  | (62,598) | (55,876) | (32,031)
Income before income taxes |  |  |  |  |  |  |  |  | 61,538 | 895,403 | 539,861
Net loss and loss expense ratio |  |  |  |  |  |  |  |  | 80.70% | 56.90% | 51.00%
Acquisition cost ratio |  |  |  |  |  |  |  |  | 17.70% | 16.60% | 15.10%
General and administrative expense ratio |  |  |  |  |  |  |  |  | 13.90% | 15.20% | 13.20%
Combined ratio |  |  |  |  |  |  |  |  | 112.30% | 88.70% | 79.30%
Goodwill and intangible assets | 99,590 |  |  |  | 103,231 |  |  |  | 99,590 | 103,231 | 91,505
Insurance [Member] |  |  |  |  |  |  |  |  |  |  |
Segment Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Gross premiums written |  |  |  |  |  |  |  |  | 2,121,829 | 1,916,116 | 1,775,590
Net premiums written |  |  |  |  |  |  |  |  | 1,466,134 | 1,332,220 | 1,025,061
Net premiums earned |  |  |  |  |  |  |  |  | 1,429,687 | 1,206,493 | 1,157,966
Other insurance related income (loss) |  |  |  |  |  |  |  |  | 2,396 | 2,073 | (130,946)
Net losses and loss expenses |  |  |  |  |  |  |  |  | (919,319) | (569,869) | (612,694)
Acquisition costs |  |  |  |  |  |  |  |  | (199,583) | (152,223) | (113,187)
General and administrative expenses |  |  |  |  |  |  |  |  | (278,147) | (276,435) | (216,954)
Underwriting income (loss) |  |  |  |  |  |  |  |  | 35,034 | 210,039 | 84,185
Net loss and loss expense ratio |  |  |  |  |  |  |  |  | 64.30% | 47.20% | 52.90%
Acquisition cost ratio |  |  |  |  |  |  |  |  | 14.00% | 12.60% | 9.80%
General and administrative expense ratio |  |  |  |  |  |  |  |  | 19.40% | 23.00% | 18.70%
Combined ratio |  |  |  |  |  |  |  |  | 97.70% | 82.80% | 81.40%
Goodwill and intangible assets | 99,590 |  |  |  | 103,231 |  |  |  | 99,590 | 103,231 | 91,505
Reinsurance [Member] |  |  |  |  |  |  |  |  |  |  |
Segment Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Gross premiums written |  |  |  |  |  |  |  |  | 1,974,324 | 1,834,420 | 1,811,705
Net premiums written |  |  |  |  |  |  |  |  | 1,953,300 | 1,815,320 | 1,791,368
Net premiums earned |  |  |  |  |  |  |  |  | 1,885,274 | 1,740,917 | 1,633,798
Other insurance related income (loss) |  |  |  |  |  |  |  |  | 0 | 0 | 1,265
Net losses and loss expenses |  |  |  |  |  |  |  |  | (1,755,733) | (1,107,263) | (811,178)
Acquisition costs |  |  |  |  |  |  |  |  | (387,886) | (336,489) | (307,308)
General and administrative expenses |  |  |  |  |  |  |  |  | (103,915) | (98,001) | (76,127)
Underwriting income (loss) |  |  |  |  |  |  |  |  | (362,260) | 199,164 | 440,450
Net loss and loss expense ratio |  |  |  |  |  |  |  |  | 93.10% | 63.60% | 49.60%
Acquisition cost ratio |  |  |  |  |  |  |  |  | 20.60% | 19.30% | 18.80%
General and administrative expense ratio |  |  |  |  |  |  |  |  | 5.50% | 5.70% | 4.70%
Combined ratio |  |  |  |  |  |  |  |  | 119.20% | 88.60% | 73.10%
Goodwill and intangible assets | 0 |  |  |  | 0 |  |  |  | 0 | 0 | 0
Unallocated To Segment [Member] |  |  |  |  |  |  |  |  |  |  |
Segment Information [Line Items] |  |  |  |  |  |  |  |  |  |  |
Corporate expenses |  |  |  |  |  |  |  |  | (77,089) | (75,449) | (77,076)
Net investment income |  |  |  |  |  |  |  |  | 362,430 | 406,892 | 464,478
Net realized investment gains (losses) |  |  |  |  |  |  |  |  | 121,439 | 195,098 | (311,584)
Foreign exchange (losses) gains |  |  |  |  |  |  |  |  | 44,582 | 15,535 | (28,561)
Interest expense and financing costs |  |  |  |  |  |  |  |  | $ (62,598) | $ (55,876) | $ (32,031)

X
- Definition Acquisition costs divided by net premiums earned + References No definition available. + Details
Name: | axs_AcquisitionCostRatio
Namespace Prefix: | axs_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Sum of net loss and loss expense ratio, acquisition cost ratio and general and administrative expense ratio + References No definition available. + Details
Name: | axs_CombinedRatio
Namespace Prefix: | axs_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition General and administrative expenses divided by net premiums earned + References No definition available. + Details
Name: | axs_GeneralAndAdministrativeExpenseRatio
Namespace Prefix: | axs_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The carrying amount, as at the balance sheet date, of goodwill and intangible assets (both finite and indefinite-lived), which represents the cumulative amount paid net of any accumulated impairment and amortization charges. + References No definition available. + Details
Name: | axs_GoodwillAndIntangibleAssetsNet
Namespace Prefix: | axs_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the net gain or loss, both realized and unrealized, on other investments, as well as the total of all interest and dividend income on available-for-sale debt and equity securities (including any amortization/accretion of discounts/premiums) and interest income earned on cash and cash equivalents, net of related investment expenses. + References No definition available. + Details
Name: | axs_InvestmentIncomeNetForInvestmentsAndCashAndCashEquivalents
Namespace Prefix: | axs_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Net losses and loss expenses divided by net premiums earned + References No definition available. + Details
Name: | axs_NetLossAndLossExpenseRatio
Namespace Prefix: | axs_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The net realized gains or losses on available for sale investments recognized during the period, including the credit loss component of OTTI, and the change in fair value of investment-related derivatives. + References No definition available. + Details
Name: | axs_NetRealizedGainsLosses
Namespace Prefix: | axs_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Total number of reportable segments for the entity. + References No definition available. + Details
Name: | axs_NumberOfReportableSegments
Namespace Prefix: | axs_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Total consideration paid and payable by direct policyholders for insurance contracts sold by the Entity during the period and premiums for all insurance assumed from other insurers, that is premiums ceded to the Entity by other insurers. + References No definition available. + Details
Name: | axs_PremiumsWrittenGross
Namespace Prefix: | axs_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Net premiums earned less: net losses and loss expenses, acquisition costs and general and administrative expenses directly related to underwriting activities. + References No definition available. + Details
Name: | axs_UnderwritingIncomeLossNet
Namespace Prefix: | axs_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of deferred policy acquisition costs charged to expense in the period, generally in proportion to related revenue earned, estimated gross profits, or over the customer relationship or some other period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6967983&loc=d3e11264-158415 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 7 -Article 7 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 45 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6480726&loc=d3e6691-158385 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 16 -Article 12 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 30 -Section 35 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=6481450&loc=d3e10157-158409 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 60 -Paragraph 60 -Subparagraph c -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.7(a)) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Statement of Position (SOP) -Number 95-1 -Paragraph 19, 20, 21, 22, 23 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 18 -Article 12 Reference 10: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 97 -Paragraph 22, 23, 24, 25, 26 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
Name: | us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The aggregate foreign currency transaction gain (loss) (both realized and unrealized) included in determining net income for the reporting period. Excludes foreign currency transactions designated as hedges of net investment in a foreign entity and intercompany foreign currency transactions that are of a long-term nature, when the entities to the transaction are consolidated, combined, or accounted for by the equity method in the reporting enterprise's financial statements. For certain enterprises, primarily banks, that are dealers in foreign exchange, foreign currency transaction gains (losses) may be disclosed as dealer gains (losses). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450189&loc=d3e30690-110894 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 52 -Paragraph 30 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6450189&loc=d3e30700-110894 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 830 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450222&loc=d3e30840-110895 + Details
Name: | us-gaap_ForeignCurrencyTransactionGainLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 4 -Section 08 -Paragraph h -Subparagraph 1(i) Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)(1)(i)) -URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690 + Details
Name: | us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cost of borrowed funds accounted for as interest that was charged against earnings during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.9) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 34 -Paragraph 21 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 9 -Article 9 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher OTS -Name Federal Regulation (FR) -Number Title 12 -Chapter V -Section 563c.102 -Paragraph 9 -Subsection II -LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy. + Details
Name: | us-gaap_InterestExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The total amount of other operating income, the components of which are not separately disclosed on the income statement, from items that are associated with the entity's normal revenue producing operation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 + Details
Name: | us-gaap_OtherOperatingIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Other generally recurring costs associated with normal operations excluding those directly related to the marketing or selling of products and services not otherwise defined. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.4) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 + Details
Name: | us-gaap_OtherSellingGeneralAndAdministrativeExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Provision for benefits, claims and claims settlement expenses incurred during the period net of the effects of contracts assumed and ceded. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 5 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.5) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 + Details
Name: | us-gaap_PolicyholderBenefitsAndClaimsIncurredNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Premiums earned on the income statement for all insurance and reinsurance contracts after subtracting any amounts ceded to another insurer and adding premiums assumed from other insurers. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.13(c)) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 1 -Article 7 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 113 -Paragraph 27 -Subparagraph a, b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.1) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 + Details
Name: | us-gaap_PremiumsEarnedNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Premiums written for all insurance and reinsurance contracts, after adding premiums assumed from other insurers and subtracting any amounts ceded to another insurer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 17 -Article 12 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 113 -Paragraph 27 -Subparagraph a, b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 605 -Section 50 -Paragraph 1 -Subparagraph (b),(c) -URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547 + Details
Name: | us-gaap_PremiumsWrittenNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_SegmentReportingInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The aggregate total amount of expenses directly related to the marketing or selling of products or services. + References No definition available. + Details
Name: | us-gaap_SellingAndMarketingExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration