INVESTMENTS - Restricted assets (Details) - USD ($)		12 Months Ended
Jan. 01, 2019	Dec. 31, 2019	Dec. 31, 2018
Restricted Investments [Line Items]
Collateral in Trust for inter-company agreements		$ 1,580,689,000	$ 2,121,522,000
Collateral for secured letter of credit facility		473,187,000	470,051,000
Funds at Lloyd's		1,314,345,000	1,307,945,000
Collateral in Trust for third party agreements		1,856,327,000	1,510,416,000
Securities on deposit with regulatory authorities		76,229,000	64,360,000
Total restricted investments		5,300,777,000	5,474,294,000
Syndicate 2007
Restricted Investments [Line Items]
Collateral in Trust for third party agreements		365,000,000	403,000,000
Pledged cash for third party insurance and reinsurance agreements		16,000,000	39,000,000
Syndicate 1686
Restricted Investments [Line Items]
Collateral in Trust for third party agreements		169,000,000	0
Pledged cash for third party insurance and reinsurance agreements		$ 181,000,000	$ 154,000,000
Axis Corporate Capital UK Limited
Restricted Investments [Line Items]
Capital support, percentage	70.00%	70.00%
Axis Corporate Capital UK Limited II
Restricted Investments [Line Items]
Capital support, percentage	30.00%	30.00%

Pledged Cash For Third Party Insurance And Reinsurance Agreements

No definition available.

Name:	axs_PledgedCashForThirdPartyInsuranceAndReinsuranceAgreements
Namespace Prefix:	axs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying amount as of the date of the latest financial statement presented of securities which are owned but transferred to serve as collateral for inter-company insurance and reinsurance agreements, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party.

+ References

No definition available.

+ Details

Name:	axs_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForIntercompanyInsuranceAndReinsuranceAgreements
Namespace Prefix:	axs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying amount as of the date of the latest financial statement presented of securities which are owned but transferred to serve as collateral for insurance and reinsurance agreements with third parties, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party.

+ References

No definition available.

+ Details

Name:	axs_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForThirdPartyInsuranceAndReinsuranceAgreements
Namespace Prefix:	axs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Pledged Financial Instruments, Underwriting Support

+ References

No definition available.

+ Details

Name:	axs_PledgedFinancialInstrumentsUnderwritingSupport
Namespace Prefix:	axs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Restricted Investments [Line Items]

+ References

No definition available.

+ Details

Name:	axs_RestrictedInvestmentsLineItems
Namespace Prefix:	axs_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of capital support provided to Lloyd's Syndicate 1686.

+ References

No definition available.

+ Details

Name:	axs_SyndicateCapitalSupportPercentage
Namespace Prefix:	axs_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount of cash and investment securities on deposit with state regulatory authorities in connection with capital requirements.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 825
-Section 50
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=75763970&loc=SL75763979-209797

+ Details

Name:	us-gaap_AssetsHeldByInsuranceRegulators
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of restricted investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleRestricted
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying amount as of the date of the latest financial statement presented of securities which are owned but transferred to serve as collateral for letter of credit arrangements, and for which the transferee does not have the right by contract or custom to sell or re-pledge them to an unrelated party.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729

+ Details

Name:	us-gaap_PledgedFinancialInstrumentsNotSeparatelyReportedSecuritiesForLetterOfCreditFacilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	srt_CounterpartyNameAxis=axs_NovaeSyndicate2007Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=axs_AXISSyndicate1686Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=axs_AxisCorporateCapitalUKLimitedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidatedEntitiesAxis=axs_AxisCorporateCapitalUKLimitedIIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: