Amount of accrued obligation to policyholders that relates to insured events for long-duration contracts.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 40

-Section 25

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=28366191&loc=d3e13145-158430

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 13

-Subparagraph a

-Article 7

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.13(a)(1))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_LiabilityForFuturePolicyBenefits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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

- Definition

Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation.

+ References

No definition available.

+ Details

Name:	xlgroup_DisposalGroupIncludingDiscontinuedOperationConsideration
Namespace Prefix:	xlgroup_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Estimated amount of assets that will be retained on a funds-withheld basis upon consummation of the transaction

+ References

No definition available.

+ Details

Name:	xlgroup_EstimatedAssetsFundsWithheld
Namespace Prefix:	xlgroup_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The estimated amount of future policy benefit reserves that will be retained upon consummation of the transaction.

+ References

No definition available.

+ Details

Name:	xlgroup_EstimatedFuturePolicyBenefitReserveRetention
Namespace Prefix:	xlgroup_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The estimated reinsurance recoverable asset that will be recorded upon consummation of the transaction.

+ References

No definition available.

+ Details

Name:	xlgroup_EstimatedReinsuranceRecoverableAsset
Namespace Prefix:	xlgroup_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Pro Forma Effect of Sale, After Tax Net Loss

+ References

No definition available.

+ Details

Name:	xlgroup_ProFormaEffectofSaleAfterTaxNetLoss
Namespace Prefix:	xlgroup_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Pro Forma Effect of Sale, Reduction To Book Value

+ References

No definition available.

+ Details

Name:	xlgroup_ProFormaEffectofSaleReductionToBookValue
Namespace Prefix:	xlgroup_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Quota Share Reinsurance Percentage

+ References

No definition available.

+ Details

Name:	xlgroup_QuotaShareReinsurancePercentage
Namespace Prefix:	xlgroup_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Sale of Subsidiary Stock, Percentage

+ References

No definition available.

+ Details

Name:	xlgroup_SaleofSubsidiaryStockPercentage
Namespace Prefix:	xlgroup_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Subsequent Event (Details) (USD $)			0 Months Ended
Subsequent Event (Details) (USD $)	Mar. 31, 2014	Dec. 31, 2013	May 01, 2014 Subsequent Event XL Re Life (SAC) Ltd.	May 02, 2014 Subsequent Event XL Re Life (SAC) Ltd.	Mar. 31, 2014 Life Operations Segment XL Re Life (SAC) Ltd.
Subsequent Event [Line Items]
Percentage of ownership sold			100.00%
Cash consideration for sale of business				$ 570,000,000
Percentage quota share reinsurance agreement				100.00%
Future policy benefit reserves	4,811,357,000	4,803,816,000			4,800,000,000
Estimated future policy benefit reserve retention				438,000,000
Estimated reinsurance recoverable asset				4,400,000,000
Estimated assets, funds withheld				5,500,000,000
Pro Forma Effect of Sale, Reduction To Book Value			585,000,000
Pro Forma Effect of Sale, After Tax Net Loss			$ 580,000,000