GOODWILL AND INTANGIBLE ASSETS (DETAILS 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011
Finite-Lived Intangible Assets [Line Items]
Intangible assets with a finite life - annual future amortization year one	$ 2
Intangible assets with a finite life - annual future amortization year two	2
Intangible assets with a finite life - annual future amortization year three	2
Intangible assets with a finite life - annual future amortization year four	1
Intangible assets with a finite life - annual future amortization year five	$ 1
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated remaining useful life (years)	9
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated remaining useful life (years)	27

Remaining useful life of finite-lived intangible assets in years.

No definition available.

Name:	axs_FiniteLivedIntangibleAssetRemainingUsefulLife
Namespace Prefix:	axs_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of amortization expense expected to be recognized during year five of the five succeeding fiscal years.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph a(3)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(3)

-URI http://asc.fasb.org/extlink&oid=6905858&loc=d3e16323-109275

+ Details

Name:	us-gaap_FutureAmortizationExpenseYearFive
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of amortization expense expected to be recognized during year four of the five succeeding fiscal years.

+ References

+ Details

Name:	us-gaap_FutureAmortizationExpenseYearFour
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of amortization expense expected to be recognized during year one of the five succeeding fiscal years.

+ References

+ Details

Name:	us-gaap_FutureAmortizationExpenseYearOne
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of amortization expense expected to be recognized during year three of the five succeeding fiscal years.

+ References

+ Details

Name:	us-gaap_FutureAmortizationExpenseYearThree
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of amortization expense expected to be recognized during year two of the five succeeding fiscal years.

+ References

+ Details

Name:	us-gaap_FutureAmortizationExpenseYearTwo
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration